GEOLOGICAL  SURVEY  OF  PENNSYLVANIA. 


FINAL  REPORT  ORDERED  BY  LEGISLATURE,  189L 


A 
SUMMARY  DESCRIPTION 

OF    THE 

GEOLOGY  OF  PENNSYLVANIA, 


IN  THREE  VOLUMES, 


A  NEW  GEOLOGICAL  MAP  OF  THE  STATE, 
A  MAP  AND  LIST  OF  BITUMINOUS  MINES, 

And  many  Page  Plate  Illustrations. 


By  J.  P.  LESLEY,  State  Geologist. 


VOL.  I. 

DESCRIBING   THE 

LAURENTIAN,  HURONIAN,  CAMBRIAN  AND  LOWER  SILURIAN 
FORMATIONS. 


HARRIS  BURG: 

PUBLISHED    BY   THE    BOARD    OF   COMMISSIONERS 
FOR    THE    GEOLOGICAL   SURVEY. 


BOARD  OF  COMMISSIONERS. 


His  Excellency  ROBERT  E.  PATTISON,  Governor, 

and  cf-officio  President  of  the  Board,  Harrisburg. 

ARIO  PARDEE, Hazleton. 

WILLIAM  A.  INGHAM, Philadelphia. 

HENRY  S.  ECKERT,     Reading. 

HENRY  McCoRMiCK, Harrisburg. 

CHARLES  A.  MINER, Wilkes-Barre. 

JOSEPH  WILLCOX, Philadelphia. 

Louis  W.  HALL, Harrisburg. 

SAMUEL  Q.  BROWN, Pleasantville. 

CHARLES  H.  NOYES, Warren. 

W.  W.  H.  DAVIS, Doylestown. 


SECRETARY  OF  THE  BOARD. 
WILLIAM  A.  INGHAM,    .       .       Philadelphia. 


STATE  GEOLOGIST. 
PETER  LESLEY, Philadelphia. 


Entered   for  the  Commonwealth  of  Pennsylvania,  in  the  year  1892,   according  to  acts  of 

Congress, 

By    WILLIAM    H.    INGHAM. 

Secretary  of  the  Board  of  Commissioners  of  the  Geological  Sun-rii. 

In  the  office  of  the  Librarian  of  Congress,  at 

WASHINGTON.  D.  C. 


UNIVERSITY  OF  CALIFORNIA 
>     f  SANTA  BARBARA 

Ptl 

in  I 


LETTER  OF  TRANSMITTAL. 


To  His  Excellency  Governor  ROBERT  E.  PATTISON,  Ex- 
officio  Chairman  of  the  Board  of  Commissioners  of  the 
Geological  Survey  of  Pennsylvania : 

SIR  :  I  have  the  honor  to  submit  to  your  approval  this 
First  Volume  of  the  Final  Report  ordered  by  act  of  Legis- 
lature, approved  in  June,  1891  ;  being  a  Summary  of  the 
results  of  the  Survey  from  its  beginning  in  June  1874  to 
the  close  of  its  field  work,  June  1,  1890  ;  since  which  date 
office  work  has  been  continued  for  the  completion  of  its 
publications  ;  chiefly  the  last  sheets  of  the  Anthracite  sur- 
vey, the  maps  and  sections  of  the  survey  of  the  New  Red 
belt  of  Bucks  and  Montgomery  counties,  the  completion  of 
the  Bituminous  colliery  map  of  Western  Pennsylvania, 
and  a  new  Geological  State  Map.  These  will  be  published 
in  the  coming  summer,  together  with  the  Second  and  Third 
volumes  of  this  Final  Report. 

In  writing  this  Summary  I  have  quoted  from  more  than 
a  hundred  volumes  of  reports  published  by  the  Board 
since  1875,  a  complete  list  of  which,  with  an  Index  to  their 
subjects,  will  be  found  at  the  close  of  the  third  volume. 

In  every  case  I  have  given  credit  to  and  thrown  respon- 
sibility upon  the  assistant  geologist  who  made  the  obser- 
vation, or  reported  the  fact  quoted,  by  a  reference  in  text 
or  foot  note  to  date  and  page  of  his  report. 

Most  of  the  illustrations  are  photo-electrotype  reduc- 
tions, and  therefore  fac-similes  of  the  drawings  made  by 
the  assistant  geologists,  or  in  the  office  of  the  Survey 
from  their  sketches,  or  from  data  in  the  text  of  their  re- 
ports, published  in  their  reports  during  the  course  of  the 
Survey. 

The  smaller  illustrations  are  grouped  on  page  plates  to 


iv  GEOLOGICAL   SURVEY    OF   PENNSYLVANIA. 

diminish  the  cost  of  the  publication  and  to  hasten  its  com- 
pletion. They  form  in  fact  an  illustrated  index  to  the 
maps  and  sections  to  be  found  (on  a  larger  scale)  in  the 
series  of  reports. 

The  names  and  districts  of  all  the  assistants  on  the  sur- 
vey will  be  found  in  a  list  at  the  end  of  the  third  volume. 

I  have  endeavored  to  confine  the  text  of  the  book  to 
general  and  systematic  statements;  and  have  therefore 
placed  all  the  detailed  local  and  ancillary  matter  in  foot 
notes.  I  trust  that  this  will  accommodate  the  reader  as 
much  as  it  has  lessened  the  size  of  the  book. 

I  have  written  it  also  in  Saxon  English,  as  far  as  a 
work  of  physical  science  can  be  so  written,  as  it  is  in- 
tended for  the  use  of  the  people  of  Pennsylvania,  in  whose 
vocabulary  Norman  English  has  never  been  domesticated, 
who  greatly  prefer  before  and  after,  or  before  and  behind, 
to  anterior  and  posterior,  and  overlaid  and  underlaid  to 
superimposed  and  subjacent,  as  I  do  myself,  and  who  are 
mostly  or  wholly  ignorant  of  Latin  and  Greek. 

Although  the  personal  element  can  never  be  entirely 
suppressed  from  any  work  of  man,  I  have  endeavored  to 
avoid  dogmatic  statements  not  made  by  a  consensus  of 
the  geological  opinion  of  to-day,  and  to  place  the  many 
differences  of  that  opinion  still  remaining  unsolved  in 
such  a  light  as  to  show  that  our  science  is  not  an  oligarchy 
but  a  democratic  republic,  in  which  every  voice  has  a  right 
to  be  heard,  and  that  even  after  the  vote  has  been  taken 
there  remains  the  right  of  calling  for  a  re-consideration 
of  it. 

The  book  is  almost  wholly  a  practical  description  of  facts 
discovered  or  verified  by  the  observation  of  the  members 
of  the  corps  of  the  Geological  Survey  in  their  several  dis- 
tricts, not  at  all  influenced  by  geological  theories,  but  sim- 
ply seen  and  measured,  and  placed  in  their  true  relations 
to  one  another. 

The  arrangement  of  the  book  will  be  seen  by  consulting 
the  Table  of  Contents.  The  order  of  description  is  chrono- 
logical from  oldest  to  newest,  but  the  representation  of 
of  each  formation  is  made  as  in  a  columnar  section  from 


LETTER   OF   TRANSMITTAL.  V 

the  top  to  the  bottom,  by  which  the  mental  conception  of 
the  pile  of  strata  is  enforced  by  the  eye.  A  descriptive 
section  with  the  bottom  bed  on  top  is  an  old-fashioned 
abomination  repudiated  now  by  all  good  geologists. 

The  page  plates  of  fossils,  placed  in  all  cases  at  the  end 
of  the  chapters  of  the  several  formations,  are  half -sized  re- 
productions of  the  figures  of  fossils  given  in  Report  P4, 
Dictionary  of  the  Fossils  of  Pennsylvania  and  the  sur- 
rounding States,  published  in  3  volumes  in  1889-1890.* 

The  Dictionary  has  been  so  successful  that  the  demand 
for  it  has  long  since  outrun  the  edition  ;  and  the  office  of 
the  survey  is  in  receipt  of  requests  for  it  which  cannot  be 
answered  because  the  edition  is  exhausted.  It  has  been  a 
completely  successful  experiment.  But  there  has  been  a 
call  for  the  classification  of  the  figures  under  the  head  of  the 
formations  to  which  the  fossils  properly  belong,  and  I  have 
endeavored  to  meet  this  call  by  grouping  the  figures  of  each 
formation  in  a  series  of  page  plates,  which  will  sufficiently 
index  the  Dictionary  for  geological  purposes. 

In  the  case  of  each  series  the  grouping  begins  with  plants, 
and  proceeding  upward  in  the  order  of  life  through  species 
of  bryozoa  and  corals,  brachiopod,  gasteropod,  cephalopod, 
phyllopod  and  lamillibranch  shells,  annelids,  crustaceans, 
insects,  and  vertebrate  fish  and  reptiles,  so  far  as  the  for- 
mation in  question  contains  these.  Where  references  to 
authority  and  locality  are  wanting  the  reader  must  consult 
the  Dictionary.  These  page  plates  are  for  popular  instruc- 
tion and  not  for  the  use  of  experts. 

J.  P.  LESLEY, 

1008  CLINTON  STRBET,  PHILADELPHIA, 
February  IS,  1892. 

*  P4,  Vol.  4,  Appendix,  was  forbidden  by  the  Board  to  be  published  until 
after  the  final  report  and  other  publications  of  the  survey  had  been  printed, 
for  fear  of  delaying  these.  In  consequence  of  this  action,  I  have  been  pre- 
cluded from  inserting  in  these  page  plates  many  of  the  fossil  forms  found  in 
Pennsylvania  and  elsewhere  recently,  many  of  them  of  the  most  inter- 
esting character. 


VOL.  I. 
TABLE   OF  CONTENTS. 


I.  Our  Geological  Knowledge, 1 

II.  Geological  Time,  how  measured,  ...       .  5 

III.  Geological  Dimension;  area,  outcrop,  dip, 

thickness, 22 

IV.  General  sections;   typical  sections;    local 

sections;  columnar  sections,     ....  30 

V.  The  Appalachian  sea,      35 

VI.  The  Names  of  the  Formations, 39 

VII.  Archaean, Azoic,  Highland, Laurentian, Fun- 
damental gneiss,  Crystalline  schists,  .  53 
VIII.  Archaean  Highland  Belt  in  Pa.  and  N.  J  ,  63 
Archaean  Types  in  New  Jersey,  ....  71 
IX.  Archaean  rocks  of  Pa.,  Reading  and  Dur- 
ham hills, 74 

In  northern  Chester  county, 75 

In   Bucks,   Montgomery  and   Delaware 

counties, 79 

On  the  Schuylkill  river, 91 

X.  Are  the  Archaean  rocks  sedimentary  ?     .    .  95 

The  argument  from  Olivine, 98 

The  argument  from  Serpentine,   ....  101 

Delaware  Co.  serpentines, 102 

Chester  Co.  serpentines, 103 

Lancaster  Co.  serpentines, 104 

Northampton  Co.  serpentines,     ....  105 

The  argument  from  Labradorite,      .    .    .  107 

The  argument  from  Marble, 109 

The  argument  from  Apatite, 113 

The  argument  from  Iron  ore, 115 


viii  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

Chapter.  Page> 

XL  The  Newer  Gneiss  of  the  Philadelphia  belt,  118 

Its  three  sub-divisions, 120 

1.  The Philadelphia(lower)  sub-division,  121 

2.  The  Manayunk  (middle)  sub-division,  122 

3.  The  Chestnut  Hill(upper)sub-division,  123 
The  Chestnut  Hill  fault, 125 

XII.  The  Philadelphia  rocks  in  Chester,  Lancas- 
ter and  York  counties, 127 

The  Newer  Gneiss  in  York  county,    .    .  128 

The  Newer  gneisses  in  Maryland,    .    .    .  130 

XIII.  Hydro-mica  slate  formation;  phyllite  belts 

of  York  and  Lancaster  counties ;  South 

Valley  Hill  slate  of  Chester  Co.,     .    .  133 

Main  York  Co.  phyllite  belt 134 

Southern  or  Peach  Bottom  belt,     ...  136 

Peach  Bottom  roofing  slates, 137 

XIV.  Geology  of  the  South  Mountains,    ....  142 
XV.  The  Huronian  System,  so  called, 152 

XVI.  For.  No.  I,  Chiques  sandstone,  Hellam 
quartzite,  North  Valley  Hill  sandstone 
of  Chester  Co.,  Potsdam  sandstone, 
Upper  Cambrian  quartzite,  Sugar  Loaf 

sandstone  of  Md., 165 

No.  I  on  the  Susquehanna, 168 

The  Chiques  Ridge  fault,      171 

No.  I,  east  of  the  Lancaster  plain,  .    .    .  173 

Rogers'  Primal  in  the  Chester  Valley,  .  175 

No.  I  in  the  Highland  range, 179 

No.  I  in  Southern  Chester  Co.,    .       .    .  181 

No.  I  in  Southern  York  Co., 182 

No.  I  in  the  Pigeon  Hill, 182 

No.  I  along  the  South  Mountains,  ...  183 

No.  I  in  Middle  Pennsylvania,     ....  186 

XVII.  On  Scolithus  linearis, 187 

XVIII.  On  Cambrian  fossil  life,  .    .           192 

XIX.  South  Valley  Hill  slate  belt, 199 

XX.  Iron  mines  in  the  Primal  Upper  Slate,   .    .  205 

York  county  limonite  banks, 211 


TABLE   OF   CONTENTS.  IX 

Chapter.  Page. 

Banks  north  of  York, 214 

Banks  west  of  York, 215 

Banks  of  the  Pigeon  Hills, 216 

Banks  near  Hanover,       217 

Banks  south  of  the  York  Valley  lime- 
stone,     219 

Banks  in  the  York  Co.  phyllite  belt.     .  220 

Banks  in  the  hydromica  belt  S.  of  York,  222 

Adams  county  limonite  banks,            .   .  225 

Lancaster  county  limonite  banks,  .    .    .  226 

Welsh  Mountain  banks, 228 

Northampton  county  limonite  mines,    .  229 

Ranges  of  Northampton  banks,  .    .    .   .  231 

Lehigh  county  limonite  mines,     ....  233 

Berks  county  limonite  mines 235 

In  Oley  valley, 236 

Cumberland  county  limonite  mines,  .    .  238 

Mountain  Creek  limonite  banks,     .    .    .  241 

Banks  along  Yellow  Breeches  creek,     .  246 

Franklin  county  limonite  banks,    .    .    .  248 

Mont  Alto  bank,       249 

Path  Valley  mines,      252 

The  two  Virginia  ranges, 253 

Grubb'sCodorus  ore  in  quartzite,  .    .    .  253 
Lehigh  Mtn.  Min.  Co.'s  mine,      ....  254 
XXI.  Magnetic  limonite   mines   doubtfully   re- 
ferred to  the  Primal  slates,  or  to  the 
Gneiss,  or  to  the  Trias,  in  York,  Ches- 
ter and  Berks  counties,      256 

In  York  county, 256 

In  Chester  county, 262 

The  Warwick  group 265 

In  Berks  county,          267 

XXII.  On  the  Great  Valley, 270 

Levels  above  tide  of  water  ways,      .    .    .  271 

The  two  belts,  limestone  and  slate,     .    .  274 

Synclinal  mountains  of  IV  in  III,         .  278 

Anticlinal  belts  of  II  in  III, 279 


viii  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

Chapter.  Page> 

XI.  The  Newer  Gneiss  of  the  Philadelphia  belt,  118 

Its  three  sub-divisions, 120 

1.  The Philadeiphia(lower)  sub-division,  121 

2.  The  Manayunk  (middle)  sub-division,  122 

3.  The  Chestnut  Hill(upper)sub-division,  123 
The  Chestnut  Hill  fault, 125 

XII.  The  Philadelphia  rocks  in  Chester,  Lancas- 
ter and  York  counties, 127 

The  Newer  Gneiss  in  York  county,    .    .  128 

The  Newer  gneisses  in  Maryland,    .    .    .  130 

XIII.  Hydro-mica  slate  formation;  phyllite  belts 

of  York  and  Lancaster  counties ;  South 

Valley  Hill  slate  of  Chester  Co.,     .    .  133 

Main  York  Co.  phyllite  belt, 134 

Southern  or  Peach  Bottom  belt,     ...  136 

Peach  Bottom  roofing  slates, 137 

XIV.  Geology  of  the  South  Mountains,    ....  142 
XV.  The  Huronian  System,  so  called, 152 

XVI.  For.  No.  I,  Chiques  sandstone,  Hellam 
quartzite,  North  Valley  Hill  sandstone 
of  Chester  Co.,  Potsdam  sandstone, 
Upper  Cambrian  quartzite,  Sugar  Loaf 

sandstone  of  Md., 165 

No.  I  on  the  Susquehanna, 168 

The  Chiques  Ridge  fault,      171 

No.  I,  east  of  the  Lancaster  plain,  .    .    .  173 

Rogers'  Primal  in  the  Chester  Valley,  .  175 

No.  I  in  the  Highland  range, 179 

No.  I  in  Southern  Chester  Co.,   .       .   .  181 

No.  I  in  Southern  York  Co., 182 

No.  I  in  the  Pigeon  Hill, 182 

No.  I  along  the  South  Mountains,  ...  183 

No.  I  in  Middle  Pennsylvania,     ....  186 

XVII.  On  Scolithus  linearis, 187 

XVIII.  On  Cambrian  fossil  life,  .    .           192 

XIX.  South  Valley  Hill  slate  belt,     .....  199 

XX.  Iron  mines  in  the  Primal  Upper  Slate,   .    .  205 

York  county  limonite  banks,   ....  211 


TABLE   OF   CONTENTS.  IX 

Chapter.  Page. 

Banks  north  of  York, 214 

Banks  west  of  York, 215 

Banks  of  the  Pigeon  Hills, 216 

Banks  near  Hanover,      217 

Banks  south  of  the  York  Valley  lime- 
stone,     219 

Banks  in  the  York  Co.  phyllite  belt.     .  220 

Banks  in  the  hydromica  belt  S.  of  York,  222 

Adams  county  limonite  banks,            .   .  225 

Lancaster  county  limonite  banks,  .    .    .  226 

Welsh  Mountain  banks, 228 

Northampton  county  limonite  mines,    .  229 

Ranges  of  Northampton  banks,  ....  231 

Lehigh  county  limonite  mines,     ....  233 

Berks  county  limonite  mines,       ....  235 

In  Oley  valley, 236 

Cumberland  county  limonite  mines,  .    .  238 

Mountain  Creek  limonite  banks,     .    .    .  241 

Banks  along  Yellow  Breeches  creek,     .  246 

Franklin  county  limonite  banks,    .    .    .  248 

Mont  Alto  bank,      249 

Path  Valley  mines,      252 

The  two  Virginia  ranges, 253 

Grubb'sCodorus  ore  in  quartzite,  .    .    .  253 
Lehigh  Mtn.  Min.  Co.'s  mine,      ....  254 
XXI.  Magnetic   limonite   mines   doubtfully   re- 
ferred to  the  Primal  slates,  or  to  the 
Gneiss,  or  to  the  Trias,  in  York,  Ches- 
ter and  Berks  counties,      256 

In  York  county, 256 

In  Chester  county, 262 

The  Warwick  group 265 

In  Berks  county,          267 

XXII.  On  the  Great  Valley, 270 

Levels  above  tide  of  water  ways,      .    .    .  271 

The  two  belts,  limestone  and  slate,     .    .  274 

Synclinal  mountains  of  IV  in  III,          .  278 

Anticlinal  belts  of  II  in  III, 279 


GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 


Page. 


Limestone  coves  in  the  slate  belt  edge,  283 

Synclinal  belts  of  III  in  II, 286 

Southern  edge  of  No.  II, 289 

Relation  of  South  Mts.  uplift  toll,    .    .  291 

XXIII.  Why  is  there  no  coal  in  the  Great  Valley  ?  294 

XXIV.  No.  II.  The  Great  Valley  limestone,  ...  298 

Sub-division  of  No.  II, 299 

XXV.   No.  II  in  the  Lehigh  region, 301 

The  folded  stratification, 306 

XXVI.  Limestone  quarries  of  the  Great  Valley  be- 
tween   the     Schuylkill    and    Snsque- 

hanua  rivers,      309 

Berks  county  quarries, 311 

Lebanon  county  quarries,      314 

Lebanon  city  group, 315 

Annville  group, 317 

Dauphin  county  quarries, 319 

Swatara  quarries,      319 

Hummelstown  group,      320 

Beaver  station  group, 321 

Paxtang  group, 322 

XXVII.  Limestone  quarries  of  the  Great  Valley  in 

Cumberland  and  Franklin, 324 

XXVIII.  MagnesianbedsinNo.il, 327 

Section  of  beds  opposite  -Harrisburg,     .  331 

Negative  deductions  from  facts,      .   .    .  334 

Amount  of  magnesia  present,      ....  334 

XXIX.  Hydraulic  cement  quarries  on  the  Lehigh,  337 

In  Mifflin  and  Centre  counties 340 

XXX.  Limonite  mines  near  the  top  of  II,  .    .    .    .  341 
Ironton  and  other  mines  in  Lehigh  Co.,  345 

Moselem  mine  in  Berks  Co., 350 

Cornwall  mine  in  Lebanon  Co.,    ....  351 

Path  Valley  mines  in  Franklin  Co..  .    .  357 

Henrietta  mines  in  Blair  Co., 361 

XXXI.  No.  II.  Nittany  Valley  limestones,     ...  365 

Centre  county  anticlinals,     ......  365 

Centre  county  cross  sections, 369 


TABLE   OF   CONTENTS.  XI 

Chapter.  Page. 

XXXII.  Centre  Co.  limonite  mines, 372 

Two  varieties  of  ore, 372 

Pennsylvania  Furnace  mine, 378 

XXXIII.  Nittany  Valley,  Huntingdon  county, mines,  387 

Pennington  range, 390 

Warrior  Mark  and  Lovetown  range,  .    .  391 

Dry  Hollow  range  in  Huntingdon  Co.,  .  391 

Cale  Hollow  range  in  Huntingdon  Co.,  394 

Huntingdon  furnace  banks,      398 

Sinking  Valley  mines, 399 

XXXIV.  Canoe  Valley  and  Morrison's  Cove,    ...  401 

The  Springfield  mines 404 

Leathercracker  Cove  ores, 409 

Morrison  Cove  ores  ;  Bloomfield  mine,  .  414 

XXXV.  Friends  Cove 419 

Milliken'sCove, 420 

Kishicoquillis  Valley, 421 

Black  Log  Valley, 422 

McConnellsburg  Cove, 423 

Horse  valley,      424 

XXXVI.  Caverns  and  Sinkholes  in  II, 425 

Rate  of  erosion  of  II, 430 

Precipitation  of  limonite  in  caves,  .    .    .  433 

Depths  of  limonite  deposits  in  caves,    .  434 

Precipitation  from  pyrites, 435 

XXXVII.  Zinc,  Lead  and  Barium  in  No.  II 436 

Saucon  zinc  mines  in  Lehigh  Co.,   .    .    .  436 

Bamford  zinc  mines  in  Lancaster,  ...  44 

Sinking  Valley  zinc  mines  in  Blair,    .    .  444 

Barytes  in  No.  II, 447 

Gypsum  absent  from  No.  II, 450 

XXXVIII.  Trap  Dykes  in  No.  II, 451 

Grand  Horseshoe  Dyke  in  Perry,    .    .    .  458 

Little  Horseshoe  Dyke,      460 

Mid  Cove  Dyke, 460 

Duncannon  Dyke. 461 

Effects  of  trap, 464 

Serpentine  in  No.  II 464 


Xii  GEOLOGICAL   SURVEY    OF   PENNSYLVANIA. 

Page. 

XXXIX.  White  limestone  and  marble  of  II,      ...  467 

In  New  Jersey, 469 

In  York  county, 473 

In  Chester  county  valley, 477 

In  Centre  county,     . 479 

XL.  Black  marble  in  No.  He., 482 

XLI.  Thickness  of  formation  No.  II, 485 

In  Lancaster  county, 485 

In  Middle  Pennsylvania, 488 

In  New  York'State, 489 

XLII.  Oil  and  Gas  in  No.  II, 492 

Why  no  Trenton  oil  or  gas  in  Pennsyl- 
vania,         494 

XLIII.  Mechanical  deposits  of  No.  II, 497 

A  peculiar  sandstone, 497 

Parkesburg  artesian  well,      498 

XLIV.  The  Fossils  of  No.  II,      501 

Fossils  of  the  Calciferous,  Ha,     .       .    .  511 

Fossils  of  the  Quebec  group, 511 

Fossils  of  the  Chazy,  lib, 513 

Fossils  of  the  Black  River,  He.,     .    .    .  513 

Fossils  of  the  Birdseye,  He. 515 

Fossils  of  the  Trenton,  He, 517 

XLV.  No.  Ill,  Utica  and  Hudson  River  forma- 
tions,      525 

The  Sea  in  which  the  Deposits  were  made,  529 

Nonconformability, 531 

Origin  of  the  pyrites,      ........  537 

Fossil  abundance 538 

Fish  discovered  under  Trenton,  ....  541 

Black  slates 542 

Limestone  intercalations,      543 

The  roofing  slate  belt, 543 

Stratification  and  foliation  of  slate,    .    .  547 

Rolls  in  the  slate, 550 

Thickness  of  the  formation,      551 

Peach  Bottom  roofing  slate, 555 

XLVI.  Thickness  of  No.  Ill,      ....  .557 


TABLE   OF   CONTENTS.  xitt 

Chapter.  Page. 

XLVII.  Character  of  No.  Ill, 562 

Fossils  in  the  formation, 565 

Quartz  veins  ;  their  origin, 566 

Flagstone  layers,      569 

Mineralogical  poverty  of  III,   .  ".    .    .    .  570 

Neither  oil  nor  gas  in  III,      571 

Iron  ore  in  III  in  New  York, 572 

XLVIII.  The  Roofing  Slate  Beds  of  No.  Ill,     ...  574 

Westward  extension  of  the  belt,     .   .   .  589 

Notes  on  the  Bangor  belt  by  R.  M,  Jones,  582 

XLIX.  The  slate  quarries  in  1882,      588 

In  Northampton  Co.,  Washington    town- 
ship,       590 

Lower  Mt.  Bethel  township, 592 

Plainfield  township, 593 

Bushkill  township,      595 

Upper  Nazareth  and  Moore, 596 

East  Allen  township, 599 

Allen  and  Lehigh  townships, 600 

In  Lehigh  Co.,  Washington  township,  .    .  604 

N.  Whitehall  and  Heidelburg,    ....  608 

S.  Whitehall  and  Lynn, 607 

In  Berks  Co.,  Albany  township, 609 

Weisenburg  and  Albany, 611 

In  Perry  township,      615 

L.  Fossils  of  No.  Ill, 617 

Peach  Bottom  fossils  for  comparison,    .  618 

LI.  No.  IV.     Oneida  and  Medina  formations,  625 

Thickness  of  No.  IV., 627 

At  the  gap  above  Harrisburg, 637 

Comparative  tables  in  the  gaps,  ....  641 

Thins  southward  and  northward,    .    .    .  649 

No.  IV  described  in  Logan  gap,      .    .   .  651 

No.  IV  at  Orbisonia, 653 

No.  IV  in  Spruce  Creek  gap, 655 

No.  IV  in  Tyrone  gap  :  section,  ....  657 

No.  IV  in  Mill  Hall  gap, 659 

No.  IV,  in  Williamsbnrg  gap,     ....  661 


GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

Page. 

No.  IV  in  the  Bedford  gaps, 661 

Oneida,  IVa,  not  deposited  there,  ...  663 
No.  IV  in  Clinton,  Centre,  Lycoming,  .  667 
No.  IV  along  the  Great  Valley,  ....  669 
No.  IV  at  the  Susquehanna  Water  Gap,  669 
No.  IV  at  the  Schuylkill  Water  Gap,  .  673 
No.  IV  at  the  Lehigh  Water  Gap,  .  -  674 
No.  IV  at  the  Delaware  Water  Gap,  .  675 

No.  IV  in  New  Jersey, 676 

No.  IV  in  New  York, 677 

Lead  ore  veins  in  No.  IV, 678 

LII.  Topographical  features  of  No.  IV,  ....    681 

Three  groups  of  mountains  of  IV,     .    .    682 
Parallelism  of  mountains  of  IV,     ...    686 
Convergence  of  mountains  of  IV,  .    .    .    688 
Mountain  spurs  of  FF,  .......    689 

Anticlinal  and  synclinal  knobs,  ....    692 

Crests,  single  and  double, 695 

Difference  in  heights,      696 

Keel  mountains  of  IV, 697 

Oneida  Terrace,  ravine  system,    ....    698 

Anticlinal  vaults  restored,     ......    699 

Model  of  the  plications  of  Middle  Penn- 
sylvania, representing  the  upper  sur- 
face of  Medina,  IVc., 703 

Methods  of  constructing  a  model,   .    .    .    704 
Conformity  of  IV  upon  III,     .....    707 
LIU.  The  mineral  worthlessness  of  the  mountains 

of  IV, 711 

Foot  notes  on  gold,  silver,  etc.,   ....    712 

LIV.  The  fossils  of  No.  IV, 714 

May  Hill  sandstone  in  England,      .    .    .    716 
The  earliest  echinus,  cockroach, 'fern,    .    716 
Lesquereux's  L.  Silurian  land-plants,    .    717 
Drifted  plants  show  changes  of  the  rela- 
tions of  land  to  sea,  and  changes  of 
vegetation  on  land, 718 


VOLUME  I. 
LIST  OF   ILLUSTRATIONS. 


276  (PI.  I).     Map  of  the  bends  of  the  Conedoguinit  creek 

in  Cumberland  Co.,  to  show  their  relation  to  the  out- 
crop contact  line  of  II  and  III. 

277  (II).  Cross  section  of  the  Great  Valley  on  the  meridian 

of  Harrisburg,  to  illustrate  Chapter  22. 

280  (III).  Map  of  the  Great  Valley  west  of  Carlisle,  to  show 

the  coves  of  II  in  the  outcrop  edge  of  III. 

281  (IV).   Cross  section  of  the  Great  Valley,   to  show  the 

hypothetical  character  of  the  Path  Valley  faults. 

284  (V). •••  •  Pig.  1,  Exposure  of  waves   in  beds  of  II;  Fig. 

2,  Local  map  of  a  limestone  cove  of  II  in  III  near 
Orrstown,  Cumb.  Co. 

285  (VI).  Fig.  1,  Cross  section  of  the  Hole,  at  Swataragap; 

Fig.  2,  A  similar  cross  section  of  Path  Valley  and 
Bear  Valley  at  Loudon,  Franklin  Co.  ;  Fig.  3,  Map 
of  southern  Franklin,  showing  the  parallel  zigzag 
outcrops  of  No.  IV,  the  parellel  alterations  of  III 
and  II  at  Mercersburg,  and  the  crenulated  edge  of 
the  limestone  belt. 

331  (VII).  Vertical  detailed  section  of  115  limestone  beds 
in  the  McCormick  quarries  opposite  Harrisburg.  with 
thickness,  and  the  percentage  of  carbonate  of  mag- 
nesia designated  by  tint. 

348  (VIII).  Figs.  1,  2,  Maps  of  Moselem  limonite  mine  and 

vicinity,  Berks  Co. — Fig.  3,  map  of  the  Lebanon  city 
and  Cornwall  part  of  the  Great  Valley. 

349  (IX).  Figs.  1,  2,  3,  Cornwall  mine  cross  sections. 

352  (X).  E.  V.  d'Invilliers'  map  of  Cornwall  mine. 

353  (XI).  Nine  illustrations  of  the  Cornwall  mine. 


XViii  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

616  (LXX).  Fossil  seaweeds  of  Peach  Bottom  slate.  P. 
Frazer. 

618  (LXXI).  Others  drawn  by  J.  P.  Lesley. 

622  (LXXII).  Photograph  of  Jack's  mountain  anticlinal 
arch. 

624  (LXXIII).  (1)  Seven     Mtns.,     6    cross    sections. 

Sketch  map  of  mountains  of  IV  from  Bald  Eagle 
across  to  Tuscarora  mountains..  (3)  Views,  map  and 
cross  section  of  an  eddy  hill  in  Big  Fishing  Creek 
Gap  in  Centre  county. 

626  (LXXIV).  (1)  Bald  Eagle  (Bellefonte)  gap,  contour 
map.  (1)  Canoe  Valley  narrows  of  the  Juniata,  Hunt- 
ingdon Co.  (3)  Map  of  zigzags  of  IV  in  Perry  Co. 

628  (LXXV).  Greenwood  Furnace  fault ;  two  sections,  and 
a  map. 

630  (LXXVI).  Bald  Eagle  faults.     Map  by  E.  B.  Harden. 

632  (LXX VII).  Port  Clinton  gap  section.     H.  M.  Chance. 

634  (LXXVIII).  Delaware  gap  section.     H.  M.  Chance. 

636  (LXXIX).  Lehigh  gap  contour  map,  by  H.  M.  Chance. 

638  (LXXX).  Delaware  gap  section.     H.  M.  Chance. 

640  (LXXXI).  Logan  gap  section,  Mifflin  Co. 

642  (LXXXII).  Lewistown  section,  Mifflin  Co. 

644  (LXXXIII).  McVeytown  section,  Mifflin  Co. 

646  (LXXXIV).  Long  Hollow  section,  Mifflin  Co. 

648  (LXXXV).  (1)  Kishicoquillis  valley  section.  (2)  Mc- 
Kee  mine  section.  (3)  Mount  Union  section. 

650  (LXXX VI).  Orbisonia  section  No.  1,  Huntingdon  Co. 

652  (LXXXVII).  Orbisonia  section,  No.  2. 

654  (LXXX VIII).  Delaware  Water  Gap  contour  map. 

656  (LXXXIX).  (1)  Jack' smtn.  anticlinal  crest  section,  to 
show  its  sudden  decline  in  Huntingdon  Co.  (2)  Map 
of  the  same.  (3)  Port  Clinton  map,  showing  fault 
at  the  Schuylkill.  (4)  Warp  of  dips,  E.  and  W. 
side  of  Delaware  Water  Gaps. 

658  (XC).  (1)  Seven  mountains,  Huntingdon  and  Union 
counties  ;  7  cross  sections  by  d'Invilliers.  (2)  Perry 
Co.  synclinals  ;  four  illustrations.  (3)  Map  of  the 
same  two  grand  synclinals. 


LIST    OF    ILLUSTRATIONS.  xix 

Page. 

660  (XCI).  Perry  county  faults  and  folds  ;  2  cross  sections 
nnd  a  map  of  Centre  township. 

662  (XCII).  Perry  Co.  fault,  four  illustrations.  (2)  Little 
Germany  fault  map.  (3)  Spring  *  township  zigzag 
belts. 

664  (XCIII).  Blue  mountain  map,  by  G.  Lehman. 

666  (XCIV).  The  same  continued  east  to  include  Port  Clin- 
ton and  the  Little  Schuylkill  river. 

668  (XCV).  Seven  Mountain  sections,  Nos.  8  and  9. 

670  (XCVI).  Seven  mountain  sections,  Nos.  10  and  11. 

672  (XCVII).  Seven  Mountain  sections,  Nos.  12  and  13. 

680  (LIII).  The  Arch  Spring  in  Sinking  Valley,  Blair  Co., 
picture  by  Lehmann,  from  Geol.  Pa.  1858.  (2) 
Catioe  mountain  terrace  (Oneida,  IVa.),  as  seen  from 
head  of  Sinking  Valley. 

700  (LVII).  Model  of  the  surface  of  the  Medina  No.  IV  in 
middle,  northern  and  northeastern  Pennsylvania,  as  it 
existed  after  elevation  and  plication,  and  before  ero- 
sion ;  constructed  by  J.  P.  Lesley.  Photograph  in 
slant  light  from  the  S.  E. 

702  (LVIII).  The  same  photographed  in  light  from  N.  W. 

714  (CXI).  Fossils  of  IV,  Oneida  and  Medina. 


INTRODUCTORY  CHAPTERS. 


CHAPTER  I. 

Our  Geological  Knowledge. 

A  summary  description  of  the  geology  of  Pennsylvania 
implies  a  condensed  account  of  all  the  work  done  by  the  ge- 
ologists of  the  state  survey  for  fifty  years,  together  with  the 
knowledge  produced  by  some  thousands  of  private  explora- 
tions. It  is  a  task  made  difficult,  not  so  much  by  the  ex- 
tent and  diversity  of  the  territory  to  be  described,  as  by 
reason  of  the  great  number  of  rock  formations  which  ap- 
pear at  the  surface,  and  the  erratic  courses  which  their  out- 
crops pursue  ;  by  the  local  variations  of  character  exhibited 
by  them  ;  by  the  complicated  structure  of  the  underground  ; 
by  the  multitude  of  mineral  beds  having  an  economical 
value  ;  by  the  eruptions  of  volcanic  rocks  in  different  places, 
and  the  extensive  rnetamorphism  of  the  older  formations  in 
the  southeastern  counties;  and  by  the  concealment  of  a  con- 
siderable portion  of  the  rock  surface  of  the  northern  and 
western  counties  beneath  a  covering  of  glacial  drift. 

So  great  is  the  variety  of  objects  of  geological  interest 
which  present  themselves  to  the  eye  of  a  skilled  observer  at 
every  point,  that  we  may  justly  consider  the  number  infi- 
nite which  offer  themselves  for  investigation  in  an  area  of 
50,000  square  miles  ;  that  is,  within  the  limits  of  our  state. 
A  small  spot  upon  the  surface  of  the  whole  globe  Pennsyl- 
vania is  nevertheless  a  world  in  itself,  to  the  just  contem- 
plation of  which  the  liveliest  imagination  can  rise  only  by 
a  great  effort ;  one  of  those  objects  of  contemplation  pre- 
sented to  the  mind  of  man  before  which  it  bows  with  all 
its  faculties  of  logic  and  rhetoric  in  reverence,  imperfectly 
comprehending  what  it  sees,  and  hopeless  of  framing  an 
adequate  salutation  to  it.  For,  the  longest  and  most  in- 
timate conference  with  these  phenomena  of  Divine  operation 


2  GEOLOGICAL   SUKVEY   OF   PENNSYLVANIA. 

will  not  enable  the  greatest  genius  to  do  justice  to  their 
description. 

The  geology  of  such  a  territory  is  a  history  of  the  works 
of  nature  through  a  lapse  of  time,  which,  if  compared  to  the 
life  of  a  man,  or  even  to  the  existence  of  the  human  race,  is 
little  less  than  an  eternity.  Events  of  the  greatest  magni- 
tude and  complexity  have  followed  each  other  in  uninter- 
rupted sequence,  without  known  beginning,  and  without 
yet  reaching  an  end.  Geologists  spend  their  lives  in  de- 
ciphering the  hieroglyphic  records  of  this  history,  only  a 
part  of  which  are  legible,  and  the  largest  part  is  concealed 
entirely  from  view.  One  fact  at  a  time  may  easily  be  noted  ; 
a  group  of  facts  may  be  compared  and  discussed  with 
pleasure  and  safety  ;  but  the  geological  drama  has  been 
played  out  upon  an  imperial  stage,  by  combined  and  con- 
flicting natural  forces  in  company,  according  to  a  plot  not 
yet  revealed,  beginning  in  ages  previous  to  the  creation  of 
any  living  being.  The  drama  was  played  without  an  audi 
ence.  Therefore,  the  geologist  who  makes  himself  its  re- 
porter is  soon  lost  in  amazed  bewilderment ;  and  when  he 
takes  his  pen  in  hand  will  pray  for  the  pardon  of  innumer- 
able mistakes  before  he  yields  to  the  necessity  of  commit- 
ting them. 

The  great  English  historian  of  the  last  century,  Gibbon, 
'has  left  for  our  instruction  a  luminous  description  of  the 
difficulties  to  be  overcome  and  of  the  successes  to  be 
achieved  by  a  narrator  of  human  events  when  twenty  years 
of  zealous  preparation  is  followed  by  twenty  years  of  patient 
execution.  He  tells  how  many  languages  had  to  be  ac- 
quired, how  many  previous  works  of  genius  mastered,  how 
many  original  documents  deciphered,  what  toil,  what 
doubts,  what  discouragements  had  to  be  endured.  He 
paints  a  touching  picture  of  the  mingled  pain  and  pleasure 
with  which  he  ended  his  task,  and  closing  his  book  bade  a 
lingering  adieu  to  the  occupation  of  his  life. 

The  geologist  is  a  historian  in  every  sense  of  the  word  ; 
subject  to  the  same  disabilities  and  exposed  to  the  same  de- 
ceptions ;  handling  a  mass  of  fragmentary  records  ;  cross- 
examining  unintelligent  and  unsympathetic  witnesses ; 


OUR  GEOLOGICAL   KNOWLEDGE.  3 

judging  conflicting  testimonies  ;  following  trains  of  events 
which  pursue  parallel  lines  separated  along  shifting  boun- 
daries but  mutually  affecting  each  other's  characters. 

But  while  the  historian  of  human  affairs  writes  under  the 
safe  guidance  of  well-known  and  well-understood  prin- 
ciples of  human  nature,  the  motives  of  which  he  has  him- 
self experienced,  and  by  which  he  may  interpret  with  a  near 
approach  to  truth  the  actions  of  his  historical  characters,  so 
as  to  rill  out  the  rude  and  slender  sketches  of  tradition,  or 
detect  and  amend  the  mistakes  of  ancient  documents,  it  is 
the  ill  fortune  of  the  geologist  to  be  compelled  to  write  the 
physical  history  of  the  globe,  or  a  part  of  it,  in  almost  com- 
plete ignorance  of  those  fundamental  principles  of  his 
science  on  which  he  should  rely  for  all  his  explanations.  It 
is  true  that  the  collection  of  geological  facts  has  become  in- 
credibly great,  but  it  is  also  true  that  from  this  very  wealth 
of  facts  springs  the  impossibility  of  any  description  of  them 
which  shall  satisfy  the  common  mind,  while  the  geologist 
himself,  if  not  completely  lost  in  the  wilderness  of  details, 
either  becomes  a  slave  to  his  own  favorite  theories,  or  stands 
uncertain  between  the  views  of  jarring  schools. 

None  of  the  greater  questions  in  geology  have  yet  been 
answered.  We  know  nothing  of  the  interior  of  the  earth 
beyond  a  depth  of  about  five  miles  and  that  only  at  a  few 
points.  We  are  ignorant  as  yet  of  the  exact  cause  of 
earthquakes,  and  of  the  origin  of  volcanoes.  The  history 
of  the  crystalline  formations  remains  mysterious.  We 
cannot  yet  explain  the  elevation  of  a  continent,  with  its 
systems  of  faults  and  folds;  nor  the  submersion  of  the- 
ocean  bed.  The  relative  distribution  of  land  and  water  has. 
been  changed  in  every  age,  but  how,  how  much,  or  whyr 
we  do  not  know.  Consequently  no  geologist  has  succeeded 
yet  in  even  plausibly  mapping  the  surface  of  the  earth  'as 
it  was  at  any  past  time,  with  river  drainage  on  land,  and 
its  deposits  in  the  sea.  The  courses  of  those  ancient  ocean 
currents  are  unproved  which  distributed  the  river  sedi- 
ments. Ancient  lakes,  with  or  without  outlets,  are  known 
to  have  existed,  but  their  limits  have  been  destroyed  and 
their  extent  is  a  matter  of  guess  work.  The  connection  of 


4  GEOLOGICAL    SURVEY    OF    PENNSYLVANIA. 

even  great  formations  in  distant  countries  has  been  broken 
and  cannot  be' restored.  The  migration  of  living  creatures 
from  one  region  of  the  globe  to  another,  under  the  stress  of 
a  change  of  temperature,  or  the  prevalence  of  enemies, 
introduces  an  element  of  deception  into  the  arrangement 
of  any  lime-table  for  the  globe,  or  even  for  a  subordinate 
division  of  one  continent.  We  know  not  if  the  sun  has 
always  shone  upon  the  earth  with  the  same  energy  of  light 
and  heat.  We  know  not  if  the  tides  in  past  ages  have  or 
have  not  been  more  efficient  at  their  work.  The  composi- 
tion of  the  atmosphere  may  have  greatly  changed,  nor  have 
we  any  means  for  settling  that  question. 

The  geologist  then  must  examine  and  describe  his  special 
region  in  a  deceptive  twilight  of  science.  Detailed  reports 
of  business  properties  are  not  affected  by  such  fundamental 
difficulties,  but  a  description  of  a  region  like  Pennsylva- 
nia pretending  to  display  a  summary  of  our  knowledge  of 
it,  must  cautiously  handle  all  the  generalities  and  be  con- 
tent to  leave  great  questions  unanswered  and  a  thousand 
facts  unexplained. 


CHAPTER  II. 

(Geological  Time. 

Time  and  space  are  the  two  eyes  with  which  man  looks 
upon  the  world,  the  two  lenses  which  he  uses  for  examin- 
ing-, defining  and  measuring  whatever  has  attracted  his 
attention  or  excited  his  thirst  for  knowledge.  In  every 
branch  of  science,  in  every  business,  in  every  handicraft, 
in  the  tine  arts,  well-defined  and  common  standard  measures 
of  time  and  space  have  been  invented,  and  in  the  present 
century  refined  to  the  utmost  precision  by  delicate  instru- 
ments. 

The  science  of  geology  has  its  own  apparatus,  and  no 
description  of  the  geology  of  a  place  or  of  a  region  can  be 
either  written  or  comprehended  unless  both  the  writer  and 
the  reader  are  inspired  by  the  sincerest  respect  for  an 
accurate  application  of  the  standards  of  time  and  space  to 
all  and  each  of  the  whole  series  of  observed  facts. 

The  idea  of  time  is  the  most  fundamental  of  all  geolog- 
ical ideas,  and  at  the  same  time  is  to  most  minds  the 
vaguest.  To  count  the  minutes  in  an  hour,  the  years  in  a 
century,  or  the  centuries  in  the  Christian  era  has  become 
a  familiar  and  easy  mental  operation  for  all  educated  per- 
sons, and  the  few]  who  have  pursued  historical  studies 
possess  clear  notions  of  dynasties  for  two  or  three  thousand 
years  before  the  time  of  Christ.  But  to  the  majority  of 
mankind  any  statement  respecting  previous  ages  in  the  geo- 
logical history  of  our  planet  is  unreadable  because  written 
in  a  time-language  which  they  cannot  appreciate.  The 
great  operations  of  nature  have  been  so  exceedingly  slow 
and  have  been  carried  on  through  so  many  ages,  each  of 
vast  duration,  that  untrained  minds  become  confused  and 
weary  with  them. 

Nevertheless  the  geologist  is  compelled  to  describe  rock 
formations  in  an  order  of  their  successive  deposits;  and  he 
can  make  their  nature  clear  in  no  other  way  than  • 


6  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

explaining  the  comparative  quietness,  or  the  comparative 
commotion  of  the  age  of  each.  Going  backward  in  time 
and  downward  through  the  rocks,  he  is  compelled  to  give 
time-names  as  well  as  mineral-names  to  the  formations  or 
groups  of  beds  which  he  describes.  Bat  his  time-names 
can  only  be  comparative,  such  as  new  and  old,  newer  and 
older,  recent,  ancient  and  archaic.  And  his  mineral-names 
also  can  only  be  comparative :  upper,  middle  and  lower. 
These  terms,  however,  can  present  no  well-defined  idea  to 
any  mind  but  that  of  a  geologist,  for  they  are  the  terms  in 
daily  use  among  men  for  events  which  run  their  course  in 
a  few  days,  or  years,  or  centuries  of  human  time,  or  for 
things  which  are  measurable  by  inches,  yards  or  miles  in  the 
country  where  those  who  use  them  live.  A  single  one  of 
the  principal  rock  formations  of  Pennsylvania  required 
more  time  for  its  deposit  than  the  duration  of  the  human 
race  from  its  first  appearance  on  the  planet  until  now.  The 
age  of  our  primeval  forest  can  hardly  compare  with  the  age 
which  one  large  coal  bed  reached  before  its  life  was  destroy- 
ed by  the  invasion  of  the  overlying  sands.  If  the  limestone 
deposits  of  the  Cumberland  valley  could  be  measured  not 
by  feet  and  yards  but  by  years  and  centuries,  and  com- 
pared with  events  of  human  history,  we  should  merely  get 
a  vague  notion  of  enormous  time,  expressed  by  the  old 
phrase  "a  thousand  years  is  as  a  single  day." 

Nevertheless,  however  ineffectual  will  prove  the  effort  to 
frame  a  clear  idea  of  the  whole  course  of  geological  time,  or 
even  to  define  with  any  distinctness  its  major  sub-divisions, 
it  is  absolutely  indispensable  for  the  understanding  of  the 
geology  of  any  region  to  suspend  our  habitual  estimates  of 
human  events,  and  substitute  for  them  the  largest  possible 
conceptions  of  geological  time,  upon  the  grandest  scale 
which  we  are  capable  of  imagining. 

To  the  human  individual  who  seldom  lives  beyond  three- 
score years  and  ten,  and  whose  short  life  is  crowded  with 
business  affairs,  time  is  considered  a  precious  commodity  to 
be  spent  with  economy,  its  loss  and  its  waste  lamented,  and 
its  use  converted  into  a  religious  duty. 

But  these  ideas  are  products  of  the  latest  age  of  human 


GEOLOGICAL  TIME.  7 

history,  and  are  essentially  ideas  of  the  modern  factory  and 
counting-room.  Disembodied  immortal  spirits  would  value 
time  by  a  different  standard.  Science,  especially  the  science 
of  geology,  'dispenses  time  as  the  commonest  drug  in  the 
market  of  the  universe. 

The  idea  of  precise  time  is  the  product  of  the  routine  of 
civilized  human  existence.  It  is  unknown  in  the  vegetable 
and  animal  worlds ;  it  is  disregarded  by  nomadic  races. 
The  idea  took  root  when  the  home  was  organized  by  woman, 
and  meals  were  cooked  at  fixed  hours  of  the  day.  It  be- 
came" "confirmed  when  superstition  organized  priestcraft, 
and  religious  ceremonies  demanded  a  calendar.  The  moon 
was  the  first  clock.  The  invention  of  the  water-clock  by  the 
ancients  was  made  for  the  benefit  of  the  wealthy  and  cere- 
monious. The  first  mechanical  clock  in  Europe  was  one 
sent  as  a  royal  present  by  the  Caliph  Haroun-Al-Rashid  of 
Bagdad  to  Charlemagne.  Even  now,  with  all  the  chro- 
nometers of  Christendom,  it  is  still  a  fact  that  nineteen- 
twentieths  of  the  human  race  have  never  seen  a  clock,  and 
have  no.practical  need  of  one. 

The  idea  of  absolutely  precise  time  came  with  the  inven- 
tion of  the  steam  engine,  the  locomotive,  and  the  telegraph, 
and  with  the  erection  of  modern  observatories.  It  bears  the 
same  relation  to  the  crude  instinct  of  time  in  the  mental 
constitution  of  the  race  that  the  few  and  costly  ingots  of 
aluminium  bear  to  the  sum  total  of  common  clay  with 
which  the  world  is  full.  But,  with  the  spread  of  civiliza- 
tion, and  the  multiplication  of  machinery,  popular  educa- 
tion will  in  the  end  fix  it  in  the  minds  of  all. 

Whatever  moves  with  regularity,  continuously,  by  steps 
or  stages  equal  to  each  other,  and  therefore  countable  with- 
out being  accountable,  or  disturbed  by  perturbations,  is  a 
clock — is  a  measurer  of  time — a  scale  by  which  the  rate  of 
the  course  of  events  can  be  recorded.  A  locomotive,  a 
power  loom,  a  printing  press,  any  engine  adjusted  by  a  gov- 
ernor to  invariable  motion,  a  sewing  machine  driven  by  a 
well-directed  foot,  is  a  clock.  All  reciprocal  motion,  all 
rotary  motion  can  be  set  to  keep  time.  The  melting  snow 
water  dropping  from  a  roof  will  furnish  a  geologist  with  a 


8  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

measure  for  calculating  the  annual  rate  of  growth  of  stalag- 
mites in  a  limestone  cave. 

The  essential  nature  of  a  clock  is  its  regularity  ;  and  that 
depends  on  the  energy  which  moves  it ;  while  the  rate  of 
its  own  particular  motion  depends  on  its  construction,  a 
short  pendulum  ticking  seconds, a  long  pendulum  ticking 
minutes. 

But  while  the  geological  world  is  full  of  natural  time- 
markers,  they  are  of  every  variety  of  construction,  and 
therefore  furnish  no  common  standard  of  time.  The  geol- 
ogist who  seeks  to  investigate  the  age  of  the  globe  stands 
like  a  purchaser  in  a  clock-makers  shop,  surrounded  by  a 
thousand  time-keepers  all  ticking  at  once  but  not  together, 
independent  of  and  indifferent  to  each  other's  rate  of  going, 
and  waiting  for  their  turn  to  be  adjusted  to  a  common  rate  ; 
the  little  ones,  like  children  out  of  school,  rollicking  in  an 
ecstasy  of  quarter  seconds  ;  larger  ones  soberly  stating 
their  movement  in  seconds  ;  here  and  there  a  great  pendu- 
lum disdaining  to  record  its  relations  to  universal  time 
oftener  than  once  a  minute. 

In  the  world  of  physical  science  entomologists,  concho- 
logists,  ornithologists  apply  to  use  only  the  little  patent 
levers  and  repeaters  ;  while  the  mineralogists,  the  geologists 
the  astronomers,  in  their  several  calculations  work  only 
with  cathedral  clocks.  But  in  all  branches  of  physical 
science  without  exception  the  differentiation  of  time  is 
accomplished  naturally  and  is  illustrated  scientifically  by 
natural  phenomena  in  one  way  or  in  another,  on  a  smaller 
or  on  a  grander  scale,  and  at  rates  so  immensely  different 
that,  while  whole  series  of  thousands  of  one  kind  complete 
their  cycles  of  existence  within  the  lifetime  of  a  man, 
others  require  a  thousand  centuries  to  substantiate  one 
item  ;  and  this  is  what  happens  in  geology. 

Now,  for  such  phenomena  geology  has  as  yet  failed  to 
find  any  precise  measuring  time-machine,  any  clock,  and 
must  still  content  itself  with  rudely  divided  scales  of  rela- 
tive proportion  without  knowing  the  actual  sizes  of  their 
aliquot  parts.  But  geologists,  being  now  emancipated 
from  the  superstitious  belief  that  God  created  the  world  in 


GEOLOGICAL   TIME.  9 

six  days,  or  in  six  ages,  are  free  to  gaze  back  along  an 
interminable  vista  of  events,  having  modern  human  history 
with  its  accurate  chronology  of  days  and  years  in  the  fore- 
ground, through  the  middle  distance  of  classical  and  monu- 
mental history  measured  by  [olympiads,  centuries  and 
dynasties,  into  a  background  of  pre-historic  and  glacial  times 
unchecked  by  any  measurable  records  ;  beyond  which  is 
dimly  seen  an  infinite  extent  of  geological  times,  ages  and 
formations,  vanishing  in  the  extreme  distance  toward  some 
absolutely  unimaginable  beginning. 

In  contemplating  this  grand  picture  from  day  to  day,  as 
the  geologist  is  obliged  to  do,  two  sentiments  take  posses- 
sion of  him :  an  admiration  for  the  variety  and  multi- 
plicity of  the  things  which  have  happened  ;  and  a  profound 
conviction  of  the  slowness  of  time,  the  infinite  patience 
with  which  the  world  has  been  made.  And  these  senti- 
ments are  the  product  of  observation  ;  are  neither  a  fancy 
nor  a  faith. 

It  is  evident  to  observation  that  the  clock  of  nature  has 
ticked  regularly;  that  the  same  physical  forces  have  oper- 
ated through  all  time  in  the  same  way  as  they  are  seen 
operating  at  the  present  moment;  that  in  every  age  rivers 
have  been  delivering  leisurely  their  burdens  to  the  sea  in 
obedience  to  the  varying  rainfall  of  the  seasons;  that  the 
forests  have  spread  and  disappeared  again,  successively 
occupying  for  centuries  the  soil;  that  living  creatures  of  a 
million  kinds  have  made  their  appearance  on  the  planet 
in  an  orderly  series,  the  rule  of  which  we  do  not  understand, 
but  the  order  of  which  is  plainly  although  not  completely 
revealed  by  fossil  remains  imbedded  in  the  rocks.  For  it 
is  impossible  for  any  sane  man  to  doubt  that  the  rate  of 
life  with  which  we  are  familiar  now  was  in  every  geolog- 
ical age  the  rate  at  which  animated  creatures  were  gener- 
erated,  grew,  propagated  their  kind  and  perished.  No 
reason  can  be  given  for  supposing  that  the  cockroach 
whose  form  is  imprinted  on  a  shalyroof  of  a  coal-bed  lived 
either  a  shorter  or  longer  life  than  the  cockroach  of  the 
modern  dwelling  ;  or  that  the  Eurypterids  in  the  Darlington 
shales  of  Beaver  county  had  a  different  life  experience 


10  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

from  that  of  any  modern  lobster  on  the  New  England 
coast.  The  great  pachyderms  whose  skeletons  have  been 
transferred  from  the  clays  of  the  Rocky  Mountains  to  the 
museums  of  New  Haven,  Philadelphia  and  Washington, 
by  Leidy,  Cope  and  Marsh,  no  doubt  lived  each  one  as 
long  a  life  as  a  modern  elephant,  rhinoceras,  tapir,  horse 
or  elk.  The  ancient  coral  reefs  of  which  the  limestone  beds 
behind  the  Blue  Mountain  at  Stroudsburg,  Danville, 
Lewistown,  Tyrone  City  and  other  places  in  middle  Penn- 
sylvania, must  have  grown  as  slowly  as  grow  now  the  Mad- 
repore reefs  off  the  Florida  coast. 

But  beyond  this  general  conviction  that  the  ordinary 
events  of  nature  in  the  mineral,  vegetable  and  animal 
worlds  have  been  pursuing  the  even  tenor  of  their  way 
through  all  geological  ages,  we  cannot  go.  We  cannot 
divide  geological  time  into  centuries,  much  less  into  years; 
but  we  can  and  must  apply  the  conviction  thus  obtained 
that  geological  events  have  slowly  come  about  to  explain 
how  they  came  about  and  in  what  order  they  occurred. 

When  this  fundamental  idea  of  immense  stretch  and  suc- 
cession in  geological  time  has  become  familiar  to  the  public 
mind  the  greatest  difficulty  will  have  been  removed  from 
the  path  of  the  geologist  in  his  efforts  to  describe  the' 
geology  of  any  district  or  region  like  Pennsylvania  ;  and 
only  for  this  reason  is  it  insisted  upon  here.  To  make  it 
still  more  plain  the  following  illustrations  of  its  truth 
will  be  adduced  and  specimens  will  be  given  of  the  calcula- 
tions of  geological  time  attempted  by  recent  writers. 

The  annual  growth  of  trees,  interrupted  by  the  winter,  is 
marked  by  their  rings  of  bark,  so  that  the  age  of  a  tree  can 
be  discovered  by  the  number  of  these  rings.  In  like  man- 
ner the  deposits  of  a  river  are  more  abundant  and  of  a 
coarser  quality  after  long-continued  rains  ;  so  that  a  section 
of  a  sand  bank  or  mud  flat  at  the  mouth  of  a  river  should 
mark  the  course  of  time  by  thin  layers  of  fine  clay  and 
coarser  sand  alternately.  This  fact  has  been  taken  ad- 
vantage of  by  those  who  have  investigated  the  history  of 
Egypt.  The  regular  inundation  of  the  Nile,  commencing  at 
midsummer  and  lasting  a  hundred  days,  covers  the  valley 


GEOLOGICAL   TIME.  11 

and  the  delta  with  a  sheet  of  fertile  mud.  The  turbid  waters 
then  fall,  the  land  emerges,  the  winter  passes.  In  March 
the  hot  dry  khamzin  blows,  and  clouds  of  sand  sweep 
across  the  surface,  depositing  a  layer  of  yellow  desert  dust 
upon  the  previous  layer  of  Nile  mud.  This  takes  place 
year  by  year  with  the  regularity  of  clock-work.  Shafts 
have  been  sunk  through  these  alternate  layers  to  the  floor 
on  which  some  monument  of  antiquity  was  erected  four 
thousand  years  ago,  and  the  counting  of  the  alternate 
layers  has  verified  its  recorded  date.  In  some  of  these  shafts 
sunk  to  a  greater  depth  fragments  of  human  pottery  have 
been  discovered,  and  by  the  number  of  layers  of  mud  and 
sand  it  has  appeared  that  human  beings  pursued  their 
handicraft  at  least  fifteen  thousand  years  ago.  It  is  evident 
that,  were  a  proper  site  on  the  shore  of  the  Mediterranean 
between  Rosetta  and  Damietta  selected  by  the  Egyptian 
government, 'and  a  shaft  sunk  deep  enough  to  reach  the 
original  bed  on  which  the  delta  of  the  Nile  began  to  be  de~ 
posited,  it  would  be  possible,  either  by  counting  the  alter- 
nate layers  of  sand  and  mud,  or  by  simply  estimating  their 
average  number  in  each  foot  or  yard  of  the  descent,  to  cal- 
culate with  considerable  accuracy  the  geological  time  at 
which  the  drainage  of  old  ^Ethiopia  adopted  the  present 
valley  of  the  Nile  for  its  most  convenient  route  to  the  sea. 

The  Nile  indeed  in  this  respect  stands  alone  among  all 
the  rivers  of  the  world  ;  the  only  river  which  receives  no 
side  streams  for  fifteen  hundred  miles  of  its  course,  re- 
sembling thus  the  unbranched  date  palms  which  spread 
their  annual  plumes  at  the  top  along  its  bank ;  the  only 
river  which  deposits  all  its  burden  during  half  a  year,  and 
waits  to  give  the  atmosphere  an  equal  chance  for  depositing 
its  special  burden  of  a  different  kind.  But  all  the  rivers  of 
the  world  have  seasons  of  copious  outflow  and  increased 
deposit ;  therefore  all  the  river  sediments  of  the  world  are 
composed  of  alternate  layers  of  coarse  and  fine  material ; 
and  as  we  go  back  in  geological  time,  making  sections  of 
older  and  older  river  sediments,  more  and  more  packed  and 
consolidated,  hardened,  dried  and  converted  into  shale  and 
sandstone  rocks,  the  geologist  observes  in  all  of  them  this 


12  GEOLOC4ICAL   SURVEY    OF   PENNSYLVANIA. 

fundamental  character  of  alternation  ;  the  incontestable 
proof  of  their  origin  as  river  sediments  ;  affording  an  irre- 
sistible conviction  that  they  grew,  layer  upon  layer,  annu- 
ally, through  ages  of  immense  duration  rudely  measurable 
by  their  several  thicknesses. 

The  same  lesson  is  taught  in  other  ways  ;  as,  for  example, 
by  the  annual  layers  of  autumn  leaves  which  have  been 
blown  upon  the  surface  and  sunk  to  the  bottom  of  still 
water  ponds  and  little  lakes  in  the  forests,  with  the  eggs  of 
insects  attached  to  them,  and  the  wings  or  bodies  of  dead 
insects  imbedded  with  them.  A  deposit  of  this  kind  i-n 
Switzerland  is  described  by  Heer  as  thirty  feet  thick,  and 
shows  thousands  of  such  alternate  layers  of  black  vegetable 
matter  and  fine  white  clay,  each  no  thicker  than  a  sheet  of 
paper,  marking  the  quiet  alternation  of  annual  seasons  for 
many  thousand  years. 

The  influence  of  wet  and  dry  seasons  in  tropical  countries 
marks  the  annual  stalactite  growth  in  limestone  caves.  For 
in  the  rainy  season  an  abundance  of  water  falling  on  the 
surface  finds  its  way  to  the  roof  of  the  cave  charged  with 
carbonate  of  lime,  and  the  dropping  in  the  cave  goes  on 
with  great  rapidity.  But  in  the  following  dry  season  the 
growth  of  the  stalactite  stops,  just  as  the  life  of  a  tree  sleeps 
during  the  winter;  and  thus  the  stalactite  has  its  annual 
rings  of  growth  like  a  tree,  from  which  its  age  can  be  esti- 
mated. The  stalagmite  floor  of  such  a  cave  consists  of  suc- 
cessive sheets  ;  and  in  the  case  of  one  Brazilian  cavern,  thirty 
thousand  of  these  annual  sheets  have  been  counted. 

There  is  a  little  brook  in  Switzerland  called  the  Tiniere, 
which  has  its  springs  in  the  mountains  of  Berne,  and  de- 
scends through  a  narrow  ravine  which  it  has  cut  for  itself 
down  to  the  bank  of  the  Lake  of  Geneva  near  Vevey.  Fed 
by  rains,  cloud- fogs  and  melting  snows  it  wears  away  the 
rocks  through  which  it  passes  and  spreads  sheet  after  sheet 
of  sand  and  clay  over  a  little  fan-shaped  mound  which  it 
has  accumulated  at  its  mouth.  A  railroad  has  been  cut 
through  this  mound,  showing  its  dome-shaped  structure, 
and  the  slow  and  gradual  way  in  which  it  has  been  made. 
In  the  sides  of  the  railroad-cut  three  long  black  streaks  are 


GEOLOGICAL   TIME.  13 

visible  one  above  the  other.  They  make  three  long  arched 
lines.  They  consist  of  vegetable  matter  mixed  with  frag- 
ments of  charcoal,  pottery,  and  the  implements  of  man. 
They  represent  three  times  at  which  some  tribe  of  Swiss 
aborigines  selected  the  mound  as  habitable  ground,  resid- 
ing upon  it  awhile  until  destroyed  or  driven  away  by  some 
unusual  violence  of  the  little  river  descending  from  the 
mountains,  or  by  some  pestilence  or  invasion  of  hostile  foes. 
Although  the  three  arched  streaks  are  separated  from  one 
another  by  only  a  few  feet,  the  intervals  must  needs  represent 
great  lengths  of  time  ;  for,  the  three  settlements  were  made 
by  different  races  ;  for,  in  the  lowest  arch  no  tools  were 
found  except  stone  axes,  and  chisels,  and  needles  of  bone. 
In  the  middle  streak  were  found  beside  these  instruments 
made  of  brass  ;  and  in  the  Upper  streak,  manufactured  tools 
of  iron  were  discovered.  Therefore  centuries  probably 
elapsed,  the  mound  always  growing  higher  and  higher  very 
slowly,  new  tribes  coming  into  the  region  with  advancing 
civilization  seeking  places  to  live  on.  As  no  alternate  layers 
in  the  mineral  constitution  of  the  mound  could  be  made  use 
of  for  calculating  this  rate  of  growth,  the  Swiss  geologists 
resorted  to  another  method,  which  is  one  of  universal  ap- 
plication in  the  geology  of  sedimentary  rocks  of  the  globe. 
They  measured  the  amount  of  water  annually  flowing  down 
the  Tiniere  ;  they  measured  the  quantity  of  solid  matter 
held  in  suspension  by  the  little  river  at  various  seasons  of 
the  year.  From  these  two  data  they  calculated  the  thick- 
ness of  stuff  spread  over  the  whole  extent  of  the  mound  in 
a  single  year,  taking  this  thickness  as  a  unit  of  measure- 
ment for  the  depth  of  the  lowest  streak  beneath  the  present 
surface  of  the  mound.  It  resulted  from  the  calculation, 
that  the  people  who  left  their  stone  axes  in  the  lowest 
streak  lived  about  seven  thousand  years  ago;  and  the  ap- 
proximate accuracy  of  the  calculation  was  confirmed  by  a 
similar  process  of  thought  applied  to  the  case  of  human 
habitations  buried  in  a  little  delta  at  the  mouth  of  one  of 
the  rivers  of  the  Jura,  by  the  gradual  enlargement  of  which 
the  lakes  of  Neufchatel  and  Bienne,  originally  one  lake, 
has  been  separated  into  two.  In  this  case  also  the  age  of 


14  GEOLOGICAL    SURVEY    OF  PENNSYLVANIA. 

the  human  remains  was  found  to  be  about  seven  thousand 
years.  But  in  both  these  cases,  which  are  exceptionally 
favorable  for  estimating  the  time  of  the  occupation  of  the 
mounds  by  man,  no  knowledge  is  obtained  respecting  the 
far  greater  lapse  of  time  previous  to  their  first  occupation 
during  which  the  two  rivers  mentioned  had  been  doing  the 
same  work  in  the  same  way,  work  the  beginning  of  which 
goes  back  into  the  last  geological  age. 

A  bridge  was  built  by  the  Romans  from  one  vertical  wall 
to  the  other  of  a  deep  and  narrow  ravine  in  the  center  of 
France.  For  unknown  ages  a  river  of  Auvergne  had  been 
working  its  channel  down  through  a  lava  bed,  undermining 
and  throwing  down  one  after  another  of  its  basaltic 
columns,  grinding  them  up  into  black  mud  and  delivering 
the- mud  to  the  Loire  to  be  deposited  in  the  Bay  of  Biscay. 
The  Roman  bridge  is  broken,  but  its  arches  still  cling  to 
the  walls  of  the  chasm,  showing  that  this  has  not  been  sen- 
sibly widened  in  two  thousand  years.  A  flagrant  proof  of 
the  extreme  slowness  with  which  the  erosion  of  the  surface 
of  the  earth  has  ever  been  going  on  ;  and  we  may  turn  from 
the  basaltic  columns  in  Auvergne  to  the  great  canon  of 
Colorado  or  any  of  the  gaps  in  the  mountains  of  middle 
Pennsylvania  with  a  sentiment  of  profoundest  conviction 
for  their  vast  antiquity.  The  process  of  destruction  is 
evident  ;  it  goes  on  before  our  eyes  daily  and  annually;  "but 
unless  we  have  a  sound  conviction  of  its  infinite  slow- 
ness we  shall  fall  into  the  popular  superstition  which  prat  ties 
about  convulsions  of  nature  which  never  occurred,  and  fails 
to  realize  the  true  character  of  the  events  which  the  geolog- 
ist has  to  describe. 

The  lesson  of  geological  antiquity  is  taught  with  equal 
clearness  by  the  series  of  volcanic  eruptions  which  mark 
the  whole  history  of  the  earth  from  the  beginning  to  the 
present  day;  and  although  evidence  of  the  exercises  of  the 
eruptive  forces  on  an  exceptionally  grand  scale  at  certain 
times  is  not  to  be  mistaken,  corresponding  to  the  greater 
and  the  more  widespread  earthquakes  which  have  some- 
times varied  the  importance  of  calamities  in  human  history, 
they  cannot  be  considered  in  any  other  light  than  as  excep- 


GEOLOGICAL    TIME.  15 

tions  to  the  regularity  of  the  whole  series  of  volcanic  phen- 
omena, which  in  the  gross  has  undoubtedly  been  as  regu- 
lar, and  has  proceeded  as  leisurely  as -any  other  function  of 
nature.  Vesuvius  at  the  Christian  era  had  been  asleep  from 
beyond  the  earliest  traditions  of  the  inhabitants  of  Italy; 
its  old  crater  was  a  cattle  ground  of  Umbrian  cow-herds, 
and  accounted  so  safe  from  all  commotion  that  Spartacus 
encamped  his  army  in  it  as  an  impregnable  fortress.  When 
the  rirst  eruption  awoke  the  mountain  to  renewed  activity, 
pouring  a  sheet  of  lava  over  Herculaneu  m  and  covering  Pom  - 
peii  and  the  surrounding  country  with  ashes,  men  were  as 
much  astonished  as  we  should  be  were  the  old  vents  in  York 
and  Adams  county  to  be  again  re-opened  and  fresh  streams 
of  lava  pour  from  them  over  our  cultivated  fields.  Since 
Pliny's  day  the  activity  of  Vesuvius  has  been  continuous, 
its  eruptions  recurring  every  few  years,  yet  without  sensi- 
bly increasing  the  size  of  the  cone.  Therefore,  the  con- 
struction of  the  cone  must  date  back  in  ages  previous  to  the 
appearance  of  man.  Every  volcanic  mountain  in  the  world 
has  grown  like  a  vegetable  bulb,  skin  over  skin,  through 
wastes  and  wildernesses  of  time  of  whfch  the  human  imag- 
ination can  form  but  a  vague  idea,  and  which  the  science  of 
geology  can  only  indicate  by  reference  to  the  geological  age 
of  that  particular  formation  in  which  the  lirst  appearance  of 
such  cones  can  be  recognized.  Every  geological  age  had  its 
own  volcanoes,  its  own  outflows  of  lava  and  its  own  tufa 
beds.  The  backward  vista  is  interminable  ;  the  cause  is 
unknown  ;  their  phenomena  have  pervaded  the  ages  from 
the  beginning. 

It  is  a  seductive  temptation  to  the  speculative  geologist 
to  translate  the  vague  ideas  of  geological  time  into  figures. 
But  whether  the  results  of  any  calculation  thus  mathe- 
matically stated  increases  our  knowledge  or  clarifies  our 
ideas  may  well  be  doubted  ;  for  after  all,  when  the  product 
of  multiplying  large  numbers  reaches  into  the  millions  it 
merely  generates  the  idea  of  vastness.  To  write  the  sum  of 
a  hundred  million  years  helps  us.  no  better  than  to  write 
the  words  infinity  or  eternity.  Yet  the  effort  at  such  a  cal- 
culation is  a  useful  exercise  of  the  mind  and  furnishes  an 


16  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

opportunity  for  examining  the  facts  which  must  be  used 
in  making  the  calculation.  With  this  end  in  view  one  or 
two  such  calculations  will  now  be  given. 

The  western  coast  of  South  America  has  been  lifted  from 
the  ocean  to  a  great  height  in  the  air  by  successive  earth- 
quakes, one  of  which  suddenly  lifted  it  three  feet  since  the 
settlement  of  Chili  by  the  whites.  Marine  shells  can  be 
broken  out  of  the  rocks  at  a  height  of  16,000  feet  above  the 
sea.  The  average  rate  of  this  upheaval  is  of  course 
unknown;  but  should  we  base  a  calculation  upon  the 
observed  rise  of  the  land  of  northern  Scandinavia,  namely, 
live  feet  in  a  century,  the  rocks  containing  these  fossil 
shells  would  be  320,000  years  old.  From  the  character  of 
the  shells  we  k-now  that  the  rocks  which  hold  them  were 
deposited  in  what  is  called  the  Jurassic  age.  But  if  all 
known  geological  time  were  represented  by  the  twelve  hour 
divisions  on  the  dial  of  a  clock,  the  Jurassic  age  would  be 
at  about  nine  or  ten  o'clock,  and  therefore  the  highest 
antiquity  we  could  give  to  the  mountains  of  South  America 
would  represent  but  a  portion  of  geological  time. 

While  parts  of  the  crust  of  the  earth  are  slowly  elevated 
other  regions  are  slowly  sinking  into  the  sea.  In  middle 
Pennsylvania  we  have  a  series  of  great  formations  lying  one 
upon  another,  all  of  them  originally  deposited  in  succession 
in  a  great  water  basin  which  in  early  times  occupied  the 
area  of  the  United  States.  Some  of  these  formations  were 
spread  upon  the  bottom  in  deep  water;  some  of  them  in 
water  so  shallow  that  they  exhibit  mud  cracks,  ripple 
marks  and  foot-prints  such  as  travelers  notice  everywhere 
on  sea  beaches.  They  hold  both  shore-living  shells  and  coral 
reefs.  These  facts  compel  us  to  believe  that  the  bottom  of 
the  Pennsylvanian  sea  kept  on  sinking  through  all  the  ages 
during  which  these  deposits  of  limestone,  sand  and  clay 
were  made  in  it ;  and  probably  at  a  rate  proportionate  to  the 
inflow  of  the  solid  materials  from  the  rivers  around  it.  The 
rate  of  sinking  is  of  course  unknown,  but  must  have  been 
as  slow  as  the  wearing  away  of  the  surrounding  lands. 
The  total  thickness  of  these  deposits,  measured  from  the  top 
of  the  coal  measures  down  to  the  bottom  of  the  great  lime- 


GEOLOGICAL   TIME.  17 

• 

stone  of  the  Nittany  valley  at  Birmingham  in  Blair  county, 
is  not  less  than  40,000  feet.  If  the  geologist  prefers  to  take 
the  Scandinavian  rate  of  elevation  as  a  measure  for  his  cal- 
culation, five  feet  in  a  century,  he  gets  800,000  years.  This 
result  is  indeed  a  most  uncertain  approximation  to  the 
truth,  and  is  of  no  scientific  value  whatever,  but  it  will  serve 
admirably  well  to  impress  upon  the  mind  the  reality  of  the 
vast  antiquity  of  that  part  of  the  surface  of  the  globe  which 
we  are  competent  to  examine.  Considering  the  fineness  of 
nineteen- twentieths,  say  ninety-nine-hundredths  of  the  13 
formations  which  appear  at  the  surface  in  middle  Pennsyl- 
vania, the'rate  of  their  deposit  must  have  been  lower  than  five 
feet  in  a  century,  and  consequently  the  length  of  time 
required  much  greater  than  the  result  of  the  calculation. 
The  tidal  layers  of  red  mud  in  which  were  found  at  Potts- 
ville  by  Dr.  Lee  and  Professor  Rogers  the  "foot-prints  of 
shore-feeding  animals,  measure  2,000  feet  in  thickness. 
The  fine  dark  mud  and  sand  formation  through  which  the  belt 
of  roofing  slate  in  Lehigh  and  Northampton  counties  runs 
is  at  least  6, 000  feet  thick.  The  Carboniferous  formation  at 
the  top  of  the  series,  with  its  slow-growing  coal-beds,  and  its 
slowly  deposited  limestone,  fireclay  and  shale  beds  is  3,000 
feet  thick.  Taking  these  three  formations  together,  apart 
from  the  other  ten,  we  have  12,000  feet  of  sediments  which 
might  have  had  a  rate  of  deposit  no  greater  than  a  few  feet 
in  a  century,  requiring  a  million  years. 

In  another  part  of  this  book  will  be  described  the  folding 
of  the  Paleozoic  formations  of  middle  Pennsylvania,  with 
basins  five  miles  deep,  and  arches  five  miles  high;  Al- 
pine ranges  which  once  traversed  our  State  ;  now  reduced  by 
the  frosts  and  waters  of  ages  to  within  a  thousand  or  two 
thousand  feet  of  the  level  of  the  sea.  A  whole  world  of 
rock  has  been  dislodged,  ground  up  and  carried  by  the 
Juniata,  the  Susquehanna,  the  Schuylkill  and  the  Delaware 
into  the  Atlantic.  All  southern  New  Jersey,  Delaware, 
Maryland  and  the  general  Tide  Plain  of  the  southern  states 
have  been  constructed  by  the  rivers  which  have  been 
engaged  since  the  age  of  the  coal  measures  in  eroding  the 
great  rock  folds  of  the  Appalachian  belt.  Can  we  find  in 
2 


18  GEOLOGICAL   SURVEY    OF   PENNSYLVANIA  . 

I 

what  goes  on  before  our  eyes  to-day  a  measure  for  this 
erosion.  Certainly  not  one  of  any  accuracy.  Yet  one  is  at 
hand  which  will  give  some  good  idea  of  it. 

The  Juniata  river  is  said  to  pass  at  Millerstown  in  Perry 
county  about  24, 000, 000  cubic  feet  of  water  per  hour  ;  hold- 
ing enough  sediment  in  suspension  to  represent  in  the  course 
of  a  year  about  1,000,000  cubic  yards  of  the  rock  waste 
which  its  innumberable  branches  are  robbing  from  the 
mountains.  Considering  the  whole  water  basin  of  the  upper 
Juniata,  the  erosion  going  on  must  lower  its  general  surface 
about  one  foot  in  1,500  years.  The  original  surface  of  the 
region  was  on  an  average  say  9,000  feet  above  the  present 
surface  of  the  country.  This  gives  us  13,560,000  years  as 
the  length  of  time  during  which  the  Juniata  has  been  carry- 
ing the  rock  waste  of  its  own  special  upper  country  into  the 
sea;  and  all  the  other  rivers  of  the  Atlantic  coast  have  been 
doing  the  same  work  at  the  same  rate  during  the  same 
length  of  time.  No  wonder  we  have  the  great  lowlands  of 
the  Atlantic  coast,  now  cultivated  by  man  ;  and  the  vast 
sloping  sea-bottom  which  has  its  continuation  under  water 
from  the  line  of  coast  far  out  to  the  submerged  precipice 
which  the  soundings  of  the  Coast  Survey  have  shown  to 
be  the  border  of  the  gulf  stream. 

The  work  done  by  the  Mississippi  river  has  been  ascer- 
tained with  considerable  accuracy  by  the  United  States 
Army  Survey  under  Humphreys  and  Abbott.  At  its 
present  rate  of  work  (which  alone  can  be  studied)  it  removes 
from  the  face  of  the  immense  region  between  the  Allegheny 
and  Rocky  mountains  one  foot  of  surface  depth  in  6,000 
years.  It  is  impossible  to  state  the  original  height  of  the 
general  surface  of  the  Mississippi  water-basin  in  the  coal 
era  when  the  great  river  began  its  operations.  From  some 
districts  like  middle  Kentucky  and  Ohio  it  has  removed  all 
the  formations  from  the  top  of  the  coal  measures  nearly  to 
the  bottom  of  the  series,  a  thickness  of  say  10,000  feet. 
In  other  parts,  as  at  Pittsburgh,  the  erosion  amounts  to  only 
2,000  feet.  If  an  average  of  only  a  thousand  feet  be  as- 
sumed the  age  of  the  Mississippi  would  be  6,000,000  years. 

The  science  of  geology  in  its  present  stage  is  like  a  river 


GEOLOGICAL   TIME.  19 

• 

bearing  variable  'quantities  of  solid  matter  which  can  be 
seen  and  felt,  and  quantities  of  invisible  chemical  solutions. 
It  consists  of  an  abundance  of  indisputable  facts,  mixed 
with  innumerable  fugitive  suggestions,  hypotheses  and" 
theories,  changeable  in  their  nature  and  subject  to  present 
and  future  criticism.  The  accumulation  of  facts  which  re- 
main the  permanent  body  of  the  science  increases  continu- 
ally and  at  an  accelerated  rate  from  year  to  year.  The 
study  of  one  mineral  bed  after  another  and  one  geological 
locality  after  another  is  gradually  procuring  a  sound  and 
useful  knowledge  of  the  structure  and  mineral  wealth  of 
regions.  Thus  the  beneficial  work  of  good  geologists  is  in 
favor  of  the  business  community,  which  troubles  itself  little 
about  questions  of  cause  and  effect,  and  is  well  content  with 
definite  statements  of  quality  and  quantity,  seeking  only  to 
learn  where  the  useful  can  be  found  and  how  it  can  be 
cheaply  got.  Yet  the  discussion  which  forever  goes  on  in 
the  geological  profession  respecting  the  origin  and  age  of 
minerals  appeals  strongly  to  the  intelligent  curiosity  of  ed- 
ucated men  of  all  classes,  and,  in  so  far  as  they  can  be 
understood  by  laymen,  make  an  important  part  of  the  gen- 
eral education  of  the  community. 

The  race  of  man  differs  from  the  races  of  animals  in  pos- 
sessing not  only  a  more  powerful  reason,  but  the  faculty  of 
imagination,  by  which  man  sees  the  invisible,  and  can  ap- 
preciate the  past.  In  science  the  business  of  the  imagina- 
tion under  the  guidance  of  mathematics  is  as  important  as 
the  business  of  the  judgment  under  the  guidance  of  the 
senses.  Without  imagination  men  would  be  like  savage 
tribes  before  the  horse  was  tamed.  The  prosaic  mind  goes 
afoot  and  travels  in  a  narrow  circle  around  its  dwelling 
place,  knowing  so  little  of  the  world  beyond  that  it  cannot 
comprehend  its  own  vicinity.  The  geologist  finds  such 
minds  everywhere.  They  are  incapable  of  seeing  what  he 
sees  both  in  the  distance  and  in  the  depth,  because  the  im- 
agination which  they  possess  has  not  been  cultivated  like 
his  own.  He  rides  his  imagination  like  a  winged  horse  in 
all  directions,  far  and  near,  collecting  knowledge  from  every 
quarter.  In  telling  his  science  he  speaks  from  horseback  to 


20  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

men  on  foot.  His  steed  may  be  better  or  worse.  He  has 
his  own  adventures  with  it.  It  sometimes  stumbles,  some- 
times he  is  thrown,  and  sometimes  he  is  run  away  with. 
When  the  imagination  is  of  the  finest  quality  it  must  be 
ridden  with  a  curbed  bit  and  a  strong  rein.  The  tendency 
to  exaggeration  in  geology  is  especially  great.  It  gathers 
force  and  velocity  by  indulgence,  like  a  rock  descending  a 
mountain  slope.  So,  exaggeration  in  the  estimate  of  geo- 
logical time  has  been  carried  by  the  vivid  imagination  of 
some  geologists  to  a  wholly  unreasonable  excess,  yet  always 
under  the  form  of  mathematical  calculation,  dealing  with 
absolute  facts  which  the  most  sober  reasoner  cannot  deny, 
and  which  are  the  products  of  the  most  careful  observation 
and  the  most  skilful  investigation  by  geographers  and 
chemists.  A  single  illustration  of  such  exaggeration  will 
suffice. 

An  English  geologist  of  eminence  has  recently  discussed 
with  great  ability  the  quantity  of  soluble  and  insoluble  sub- 
stance carried  into  the  sea  by  rivers.  Combining  Herschel's 
estimate  of  2,494,500,000,000,000,000  of  tons  of  water  in  the 
world  ocean,  with  Frankland's  analysis  of  100,000  tons  of 
sea  water  holding  1,017  tons  of  the  sulphates  of  lime  and 
magnesia,  and  49  tons  of  the  carbonates  of  lime  and  mag- 
nesia, he  gets  1,222,000,000,000,000  of  tons  of  carbonate  of 
lime  and  magnesia  in  the  world  ocean,  a  quantity  sufficient 
to  cover  50,000,000  square  miles  of  land  with  a  layer  13  feet 
deep,  and  25,000,000,000,000,000  of  tons  of  sulphate  of  lime 
and  magnesia,  a  quantity  sufficient  to  cover  the  same  num- 
ber of  square  miles  with  an  additional  layer  265  feet  thick. 

He  estimates  that  the  rivers  of  the  world  remove  annually, 
on  an  average,  from  each  square  mile  of  continental  surface 
100  tons  of  rock  matter  ;  and  that  the  proportionate  amount 
of  its  various  substances  would  be  as  follows  :  Of  car- 
bonate of  lime,  50  tons ;  sulphate  of  lime,  20  tons  ;  silica, 

7  tons ;  carbonate  of  magnesia,  4  tons  ;  sulphate  of  mag- 
nesia, 4  tons  ;  per-oxide  of  iron,  1  ton  ;  chloride  of  sodium, 

8  tons  ;  and  'alkaline  carbonates  and  sulphates,  6  tons. 
Taking  first  the  carbonates  of  lime  and  magnesia,  re- 
moved from  the  land  surface  and  deposited  in  the  sea  at  the 


GEOLOGICAL    TIME.  21 

rate  of  54  tons  per  square  mile  per  year,  it  must  have  re- 
quired 480,000  years  to  charge  the  ocean  water  with  the 
amount  of  these  salts  which  Frankland  says  it  holds. 

Taking  next  the  sulphates  of  lime  and  magnesia  he  gets 
25,000,000  years. 

Treating  the  chlorides  in  the  same  way  he  gets  200,000,000 
years. 

Estimating  the  amount  of  mechanical  sediments  or  solid 
matter  carried  by  a  river  to  the  sea  at  six  times  greater  than 
the  chemical  solution,  that  is,  40,800,000,000  tons  per 
annum ;  and  considering  the  total  surface  of  the  globe 
197,000,000  square  miles  (one  cubic  mile  weighing  10,903,- 
552,000  tons)  he  concludes  that  it  would  require  for  cover- 
ing the  whole  globe  with  a  rock  formation  of  every  kind 
one  mile  thick,  52,647,052  years  ;  and,  therefore,  if  the 
geologists  estimate  all  known  formations  taken  together  as 
measuring  10  miles  in  depth,  we  must  suppose  that  the  first 
rocks  were  deposited  526,000,000  years  ago. 

All  that  can  be  said  respecting  any  such  calculation  is 
that  it  has  no  scientific  value  whatever,  although  based  upon 
acknowledged  facts ;  but,  as  has  been  already  said,  it  will 
help  to  make  far  lower  estimates  of  the  age  of  the  world  in- 
telligible and  credible. 


22  GEOLOGICAL   SURVEY   OE   PENNSYLVANIA. 


CHAPTER  III. 

Geological  Dimension. 

The  second  fundamental  element  of  geological  thought  is 
the  idea  of  space  in  its  three  dimensions  of  length,  breadth 
and  thickness.  Any  transcendentally  imagined  fourth 
dimension  must  appear  to  be  absurd.  Astronomy  deals 
with  unimaginable  and  infinite  distances,  as  its  sister 
science,  geology,  deals  with  unimaginable  if  not  infinite 
operations  of  time.  In  both  cases  the  common  mind  is 
subject  to  a  thousand  deceptions.  Who  can  believe  that 
the  moon  when  it  rides  in  a  clear  night  through  the  atmos- 
phere to  all  appearance  no  higher  than  balloons  could 
mount  or  an  eagle  soar,  is  in  reality  240,000  miles  distant 
from  the  spectator,  sixty  times  the  radius  of  our  globe.  And 
yet  this  distance  is  the  smallest  of  the  heavenly  spaces. 
The  sun's  mean  distance  from  us  is  92,000,000  of  miles; 
while  the  light  of  the  nearest  fixed  star  traveling  at  the 
rate  of  200,000  miles  a  minute  does  not  reach  us  until  after 
a  journey  of  eight  days.  Such  ideas  would  seem  to  be  useless 
to  the  practical  geologist.  But  no  truth  is  useless;  all 
knowledge  is  practical  either  in  its  direct  application  to 
facts  or  in  its  education  of  the  finer  qualities  of  the  mind. 
No  man  can  rightly  understand  the  descent  of  a  coal  bed  or 
ore  vein  from  the  surface  into  the  depths  of  the  underground 
unless  his  imagination  is  disciplined  to  estimate  properly 
the  dimensions  of  space,  and  by  habituating  himself  to  the 
measurement  of  distances  of  all  grades,  long  and  short,  he 
acquires  the  power  of  calculating  those  lengths  and  breadths 
and  depths  which  are  within  the  scope  of  mining  opera- 
tions. 

To  the  practical  astronomer  our  globe  seems  as  small  to 
the  surrounding  solar  system  as  a  grain  of  sand  compared 
with  the  mass  of  a  mountain.  To  the  practical  geologist 


GEOLOGICAL    DIMENSION.  23 

who  compares  the  whole  globe  with  the  spot  on  its  surface 
which  he  is  studying  for  practical  purposes,  it  seems  infi- 
nitely great.  It  is  hard  to  conceive  the  depth  at  which  the 
center  of  the  earth  lies  beneath  our  feet;  it  equals  the  dis- 
tance from  San  Francisco  to  Newfoundland  or  from  Phila- 
delphia to  Berlin..  Only  those  who  travel  extensively  can 
estimate  the  size  of  the  continents  and  oceans  of  the  world; 
those  who  circumnavigate  the  globe;  he  who  travels  round 
it  in  80  days.  Were  a  continuous  first-class  railway  laid 
like  a  hoop  of  iron  on  a  great  circle,  an  express  train 
running  at  a  schedule  rate  of  40  miles  an  hour  would 
require  24  days  to  come  around  to  its  starting  point. 

Of  this  great  globe  nothing  is  known  by  the  geologist 
except  its  thinnest  skin.  The  deepest  boring  has  pene- 
trated it  only  to  the  depth  of  little  more  than  one  mile.  If 
all  known  sedimentary  and  crystalline  formations  at  their 
greatest  thickness  were  added  together,  the  sum  total 
would  not  amount  to  20  miles.  These  20  miles  in  depth  of 
rock  carry  us  back  through  all  the  known  ages  of  geolog- 
ical time.  The  rest  of  the  globe,  unknowable  and  unimag- 
inable, must  represent  an  infinite  lapse  of  previous  time. 

In  describing  an  area  of  the  earth' s  surface  like  the  State  of 
Pennsylvania,  the  first  thing  to  be  done  is  to  get  a  right  idea 
of  its  actual  size,  not  so  much  in  relation  to  the  whole  surface 
of  the  earth  as  in  relation  to  the  whole  area  of  the  North 
American  continent,  over  which  its  rock  formations  spread 
and  in  which  they  may  be  studied  far  beyond  the  limits  of  the 
state.  Pennsylvania  is  about  300  miles  long  and  150  miles 
wide,  a  mere  spot  on  the  surface  of  the  globe.  Its  geological 
formations  extend  into  surrounding  states  with  areas  as  large 
or  larger  than  its  own;  arranged  in  the  same  order  of  super- 
position one  upon  the  other;  exhibiting  similar  characters 
and  structure,  and  carrying  the  same  mineral  wealth.  As 
geological  truth  depends  upon  the  comparison  of  all  like 
facts  affecting  a  given  case,  the  geologist  of  Pennsylvania 
must  make  himself  familiar  with  the  geology  of  the  whole 
Atlantic  seaboard  and  the  whole  Mississippi  valley;  and  he 
will  often  find  the  solution  of  his  own  local  problems  five 
hundred  or  a  thousand  miles  beyond  the  border  of  his  own 


24  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

state.  On  the  other  hand  the  geology  of  New  York,  of 
Ohio,  of  Maryland,  of  Virginia,  of  West  Virginia,  of  Ken- 
tucky, gets  a  still  stronger  reflected  light  from  investigations 
pursued  for  fifty  years  in  Pennsylvania,  where  all  the  great 
formations  between  the  fundamental  rocks  and  the  coal 
measures  are  in  a  more  complete  series,  and  at  their  greatest 
known  thickness.  In  this  respect  our  state,  small  as  it  is  in 
relative  area  to  the  whole  Appalachian  region,  is  in  fact  a 
standard  of  comparison,  and  occupies  in  geology  as  in 
politics  the  position  of  the  keystone  in  an  arch.  The 
reason  for  this  will  be  explained  hereafter;  at  present  it  is 
only  needful  to  eni'orce  the  fact,  and  to  stim  ulate  the  imag- 
ination to  its  proper  comprehension,  namely,  that  our  geo- 
ology  is  not  local  but  general;  that  the  rock  formations  of 
one  county  of  our  state  are  not  confined  to  that  county,  but 
extend  in  immense  sheets,  with  practically  the  same  char- 
acter, and  lying  upon  one  other  in  the  same  order,  beneath 
the  surface  of  many  of  the  other  counties  of  the  state,  and 
also  of  extensive  regions  of  neighboring  states;  forming  in 
fact  successive  floors  beneath  nearly  the  whole  United 
States;  sometimes  rising  to  the  surface,  so  that  their  edges 
can  be  examined  along  lines  and  belts  of  greater  or  less 
length;  and  sinking  again  to  depths  of  several  miles,  where 
it  is  to  be  presumed  that  their  nature  is  unchanged;  and 
this  presumption  is  the  sole  basis,  but  a  practically  sound 
and  reliable  basis,  for  the  little  knowledge  which  we 
possess  of  the  earth's  interior. 

The  three  dimensions  of  length,  breadth  and  thickness 
then  applies  in  practical  geology  to  every  rock  formation. 
(1)  To  the  length  of  its  outcrop,  which  (in  Pennsylvania) 
runs  in  a  northeast  and  southwest  direction;  (2)  to  the  dis- 
tance which  it  extends  underground  from  southeast  to 
northwest  before  it  rises  again  to  the  surface  in  New  York 
or  in  Ohio;  and  (3)  to  the  number  of  feet,  or  yards,  or 
hundred  yards  of  its  thickness  as  measured  from  its  bottom 
bed  to  its  top  bed,  wherever  it  appears  at  the  surface. 
These  are  its  three  elements  of  size  and  quantity;  and  with 
these  three  elements  all  the  measurements  and  calculations 
of  practical  geology  are  accomplished.  If  the  slope  (or 


GEOLOGICAL     DIMENSION.  25 

angle  with  the  horizon)  at  which  a  formation  sinks  into  the 
underground  and  rises  again  to  the  surface  be  carefully 
observed,  it  becomes  possible,  and  is  usually  an  easy  matter, 
to  estimate  with  truth  its  bulk  or  solid  contents,  the  num- 
ber of  square  yards  or  tons  which  it  contains,  and  its  dis- 
tance beneath  the  surface  at  any  given  point  where  it  may 
be  desirable  to  bore  a  well  or  sink  a  shaft  to  work  it. 

This  is  the  first  business  of  the  geologist,  and  it  is  more 
successfully  pursued  than  people  imagine,  for  it  proceeds 
upon  the  well-established  application  of  geometrical  rules 
for  the  treatment  of  the  length,  breadth  and  thickness  of  all 
solid  bodies,  rules  that  are  invariable. 

If  rock  formations  were  absolutely  regular  in  their 
shape,  of  equal  thickness  everywhere,  this  practice  of  geol- 
ogy could  be  conducted  without  the  least  chance  of  mis- 
take, and  business  men  might  depend  with  absolute  re- 
liance on  the  assertion  of  a  competent  geologist  that  a  cer- 
tain rock  formation  would  be  struck  at  such  and  such  a 
depth.  But  the  case  of  a  perfectly  regular  rock  formation 
is  one  of  the  rarest  in  nature.  Not  only  every  bed  of 
limestone,  sandstone,  shale,  clay,  coal  or  iron  ore  varies 
in  thickness  within  its  own  particular  limits  of  variation, 
but  every  group  of  beds,  and  every  formation  composed 
of  groups  of  beds,  thickens  in  one  direction  and  thins  in 
another,  or  thickens  and  thins  alternately  and  irregularly 
throughout  its  whole  extent.  So  that,  were  it  not  for  the 
many  times  and  places  at  which  rock  beds  rise  to  the  sur- 
face to  be  measured  again  and  again,  these  irregularities 
would  present  an  insuperable  obstacle  to  the  accurate  prac- 
tice of  geology.  In  this  respect  the  folded  structure  of  all 
middle  Pennsylvania  gives  to  our  study  of  its  geology  an 
immense  advantage,  and  makes  our  knowledge  of  it  ex- 
tremely accurate.  But  where  the  whole  series  of  forma- 
tions lie  entirely  flat,  and  only  the  highest  members  of  the 
series  can  be  seen  at  the  surface,  as  throughout  western 
Pennsylvania  and  the  greater  part  of  the  Mississippi  basin, 
tjiey  completely  conceal  their  underground  irregularities  of 
thickness  and  quality.  The  only  knowledge  we  can  then 
obtain  of  such  irregularities  must  come  from  a  comparison 
of  the  records  of  well  borings. 


26  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

The  exact  number  of  wells  bored  in  western  Pennsyl- 
vania is  not  known,  but  it  must  exceed  50,000.  Many  of 
them  have  gone  down  only  a  few  hundred  feet,  many  more 
are  1,000  feet  deep,  few  reach  3,000,  and  the  deepest,  the 
experimental  borehole  of  Mr.  Westinghouse,  at  Pittsburgh, 
and  the  wells  at  Erie,  Franklin,  and  Wheatland  are  respec- 
tively 4,685,  4,460,  3,880,  and  3,484  feet  deep.  Had  the  re- 
cords of  all  the  wells  bored  since  1859  been  carefully  kept  and 
the  character  and  thickness  of  every  rock  stratum  been  ac- 
curately observed,  our  knowledge  of  the  underground  geo- 
logy of  western  Pennsylvania  might  be  considered  perfect. 
As  it  is,  nine-tenths  of  this  knowledge  has  been  lost.  But  the 
one-tenth  which  has  been  rescued,  taken  in  connection 
with  the  innumerable  outcrop  exposures  along  river  cliffs 
and  in  ravines,  is  quite  sufficient  to  make  the  geology  of 
that  half  of  our  state  more  accurate  and  reliable  than  the 
geology  of  any  part  of  the  known  world  ;  that  is  to  say,  to 
the  depth  of  about  a  mile.  All  the  underlying  formations 
which  only  outcrop  in  middle  Pennsylvania,  and  the  great 
crystalline  floor-rocks  which  outcrop  in  southeastern  Penn- 
sylvania, are  absolutely  unknown  in  western  Pennsylvania. 

The  expression  absolutely  unknown  is  true  indeed  only 
in  its  precise  sense.  Probabilities  are  of  every  grade 
of  force,  and  sometimes  rise  nearly  to  the  level  of  cer- 
tainties. When  eye-witnesses  cannot  be  obtained,  circum- 
stantial evidence  will  in  many  cases  prove  sufficient  for 
conviction.  If  the  head  of  a  nail  is  seen  on  one  side  of  a 
board  and  its  point  projects  from  the  opposite  side,  no 
reasonable  person  would  think  it  necessary  to  split  the 
board  to  see  if  the  nail  went  through  from  the  head  to  the 
point.  If  the  Gorniferous  limestone  formation,  No.  Villa, 
which  runs  along  the  foot  of  the  Bald  Eagle  mountain 
for  a  hundred  miles,  from  Muncy,  past  Williamsport,  Lock 
Haven,  Milesburg,  Tyrone  City,  AltoonaandHollidaysburg, 
to  Cumberland,  in  Maryland,  and  so  on  south,  as  a  contin- 
uous formation,  descending  vertically,  or  dipping  steeply 
north  west  ward,  as  if  to  go  under  the  Allegheny  mountain— 
if  this  limestone  makes  its  appearance  in  a  similar  outcrop 
along  ihe  Mohawk  valley,  in  the  State  of  New  York,  and 


GEOLOGICAL    DIMENSION.  27 

keeps  on  in  a  nearly  straight  line  westward  to  Niagara 
Falls,  reappears  on  the  southern  shore  of  Lake  Erie  near 
Cleveland,  and  runs  south  through  the  State  of  Ohio  to  the 
Ohio  river  above  Cincinnati,  and  so  on  across  Kentucky  into 
Tennessee,  no  reasonable  man  can  refuse  to  believe  that  it 
underlies,  in  a  practically  unbroken  sheet,  the  whole  region 
enclosed  between  these  two  lines,  and  must  surely  be  struck 
by  every  oil  well  if  the  drilling  goes  deep  enough.*  It  is  for 
the  geologist  to  calculate  what  that  depth  would  be  at  any 
given  point  in  the  region  ;  and  this  he  could  do  with  math- 
ematical certainty  were  the  overlying  formations  perfectly 
regular  in  thickness.  Since  they  are  not  thus  regular, 
some  law  of  irregularity  must  be  discovered,  and  this  can 
only  be  done  by  measuring  the  interval  between  the  Cor- 
niferous  limestone  and  some  coal  bed  or  limestone  at  the 
surface,  on  the  two  edges  of  the  region,  the  one  in  middle 
Pennsylvania,  the  other  in  central  New  York  and  central 
Ohio. 

Such  measurements  have  been  made  and  repeated 
until  a  pretty  accurate  average  interval  has  been  obtained 
on  each  of  these  lines  of  outcrop.  The  difference  between 
them  is  so  great  that  no  better  example  of  the  irregularity 
of  our  formations  could  be  selected. 

The  Devonian  and  sub-Carboniferous  formations  in  Ohio 
measure,  all  told,  only  1,175  feet;  in  Erie  and  Crawford 
counties,  3,000' ;  in  Clinton  county,  9,274' ;  in  Blair  county, 
10,909' ;  in  South  Huntingdon,  11,546' ;  at  Cumberland,  in 
Maryland,  11,510' ;  at  Catawissa,  in  Columbia  county, 
12,212' ;  on  the  Susquehanna  river,  above  Harrisburg, 
16,285' ;  on  the  Schuylkill  river,  between  Pottsville  and 
Schuylkiir  Haven  (they  stand  vertically)  20,000'  (?) ;  on  the 
Lehigh  river,  in  Carbon  county,  15,970' ;  at  Broadheadville, 
13,550'  ;  at  Stroudsburg,  in  Monroe  county,  13,000',  and  at 
Port  Jarvis,  along  the  Delaware  river,  in  Pike  county, 
12.750'. 


*It  has  actually  been  struck  by  three  wells,  the  Presque  Isle  well  at  Erie, 
at  a  depth  of  1,400  ;  the  Wheatlaud  well  in  Mercer  county,  at  3,384,  and  the 
Con  way  well,  nine  miles  below  Franklin,  at  3,880?  But  its  southward  dip 
carries  it  down  below  the  bottom  of  the  Westinghaus  well  at  Pittsburgh. 
(See  I  5,  Carll's  last  Report,  1890,  pages  72,  185,  188,  230.) 


28  GEOLOGICAL   SURVEY    OF   PENNSYLVANIA. 

It  is  thus  easy  to  see  that  formations  VII,  VIII,  IX,  X, 

XI  and  XII,   which  occupy  the  interval,   are  thicker  in 
Pennsylvania  than  in  Ohio,  and  as  they  are  all  deposits  of 
sand  and  clay  in  sea  water,  and  are  not  only  thicker,  but  of 
a  coarser  character  at  the  east  than  at  the  west,  four  con- 
clusions may  confidently  be  drawn,  namely,  (1)  that  the  de- 
posits came  from  the  east  and  were  floated  out  toward  the 
west ;  (2),  that  the  finer  material  was  carried  farthest  out 
to  sea  westward ;  (3)  that  the  difference  of  thickness  had 
little  or  nothing  to  do  with  the  depth  of  water;  and  (4)  that 
the  westward  thinning  must  be  gradual,  if  not  regularly 
graduated. 

If  now  we  could  be  sure  that  the  westward  thinning  was 
not  only  gradual,  but  regularly  gradual,  its  rate  would  be 
easily  obtainable,  and  then  the  thickness  of  the  interval 
could  be  calculated  with  great  precision,  say  for  every  ten 
miles  on  a  line  drawn  from  Altoona  to  Pittsburgh,  and  from 
Pittsburgh  to  Columbus  in  Ohio. 

On  such  a  supposition  the  depth  of  the  limestone  under- 
neath Pittsburgh  would  be  almost  exactly  7,600  feet. 

But  here  a  disturbing  element  enters  into  the  calcula- 
tion. The  outcropping  edges  of  formations  IX,  X,  XI  and 

XII  can  be  followed  up  the  West  Branch  Susquehanna  for 
many  miles  and  all  the  way  around  into  Ohio.     They  are 
also  brought  up  to  view  and  can  be  measured  in  the  mount- 
ain   gaps   at   Johnstown,  at    Confluence,  at    Blairsville, 
Latrobe  and  Connellsville  in  southwestern  Pennsylvania. 
We  can  see  how  they  all  diminish  in  thickness  from  the 
Allegheny  mountain  westward.     We  see  also  that  the  red 
formations  IX  and  XI  diminish  in  thickness  more  rapidly 
than  the  others,  and  become  so  thin  before  reaching  the 
Ohio  line  that  they  can  hardly  be  recognized.     This  com- 
plicates the  calculation,  so  that  we  are  forced  to  conclude 
that  the  Corniferous  limestone  must  lie  at  a  depth  beneath 
Pittsburgh  considerably  less  than  the  7600'  above  stated. 

The  law  of  irregularity  of  ocean  deposits  illustrated  by 
this  example  on  a  grand  scale  holds  good  for  all  the  sedi- 
mentary formations  of  the  world  and  makes  itself  felt  in 
the  case  of  every  individual  bed  in  every  formation,  pro- 


GEOLOGICAL   DIMENSION.  29 

ducing  local  thickenings  and  thinnings  of  every  conglome- 
rate, sandstone,  shale  or  limestone  bed;  obliging  the  careful 
geologist  to  repeat  his  measurements  everywhere,  and 
restraining  him  from  making  too  confident  predictions  of 
what  the  boring  tools  are  to  find,  or  the  precise  depth  at 
which  any  desired  bed  will  be  struck.  This  will  be  ex- 
plained more  fully  in  describing  the  oil  regions. 

Returning  to  the  subject  of  the  westward  thinning  of  our 
formations,  and  reversing  the  direction,  they  are  seen  to 
increase  in  thickness  from  the  Allegheny  mountain  east- 
ward to  their  final  outcrop  along  the  Blue  mountain  which 
borders  the  Cumberland  valley.  In  this  middle  belt  of  the 
State  we  have  uncommon  opportunities  for  studying  irreg-' 
ularities  of  rock  thickness.  The  strata  rise  to  the  surface 
and  sink  again  several  times  in  a  breadth  of  50  miles;  and 
every  time  they  rise  for  examination  going  southeast  they 
show  themselves  coarser  and  harder  and  thicker.  If  we 
took  in  our  examination  only  the  direction  from  Altoona  to 
Chambersburg  we  might  suppose  these  sediments  to  have 
been  produced  by  the  destruction  of  the  South  mountains 
of  Fayette  and  Adams  county;  but  the  formations  thin 
away  southward  through  Virginia  into  Tennessee,  as  they 
do  westward  into  Ohio;  but  in  the  other  direction,  north- 
eastward, they  increase  in  thickness  toward  the  Catskill 
mountains. 

Comparative  measurements  made  at  Altoona,  at  Hunting- 
don, in  Perry  county,  along  the  North  Branch  of  the  Susque- 
hanna  in  Montour  county,  along  the  Lehigh  river  in  Carbon 
county,  and  along  the  Delaware  in  Monroe  and  Pike 
counties,  must  remove  from  every  intelligent  mind  the  popu- 
lar and  mischievous  opinion  that  what  is  called  a  general 
section  of  a  series  of  rocks  can  be  used  for  the  practical 
purposes  of  exploration  by  anybody  who  has  it  in  hand, 
whether  he  be  a  geologist  or  not. 


30  GEOLOGICAL   SUEVEY   OF   PENNSYLVANIA. 


CHAPTER  IV. 

On  General  Sections. 

It  is  necessary  to  explain  clearly  what  this  term  "general 
section  "  means,  and  it  will  then  be  seen  that  the  common 
practice  of  writers  of  geological  reports  and  text-books  in 
placing  a  general  section  of  the  series  of  rocks  which  they 
'are  about  to  describe  on  the  first  page  of  their  description 
to  enable  their  readers  to  keep  in  mind  the  order,  character 
and  thickness  of  the  rocks,  while  in  one  way  it  facilitates 
the  understanding  of  the  description,  leads  in  another  way 
to  the  most  serious  practical  errors,  whenever  that  de- 
scription is  taken  as  a  guide  to  the  special  study  of  a  re- 
gion or  locality. 

A  vertical  section  of  a  formation  or  series  of  formations 
means  a  representation  or  drawing  of  a  deep  cut  in  the 
earth  from  the  surface  downward,  like  the  cut  made  by  a 
knife  through  a  pile  of  buckwheat  cakes  at  the  breakfast 
table.  The  character  and  thickness  of  each  cake  is  thus 
revealed  and  the  order  in  which  the  cakes  lie  one  upon  the 
other.  If  the  various  layers  lie  smooth  and  flat  the  section 
shows  it.  If  the  layers  be  crumpled  the  section  shows  it. 
If  they  differ  in  thickness  anywhere  the  section  shows  it. 
And  if  they  have  a  general  slope  or  inclination  in  one 
direction,  the  lower  layers  rise  toward  one  end  of  the  sec- 
tion, and  the  upper  layers  sink  at  the  other  end.  It  is 
called  a  vertical  section  because  it  is  made  from  the  surface 
directly  towards  the  center  of  the  earth. 

A  columnar  section  is  merely  a  small  portion  of  a  verti- 
cal section,  showing  the  same  facts  of  order,  character  and 
thickness,  by  a  narrow  column  placed  at  one  side  of  the 
printed  page,  drawn  without  any  regard  to  the  slope  or 
wrinkles  of  the  rocks,  and  representing  them  as  if  they 
were  lying  Jlat.  The  measurements  are  made  at  right 


ON   GENERAL   SECTIONS.  31 

angles  to  the  beds,  and  are  intended  to  express  the  exact 
thicknesss  of  the  several  beds.  It  is  evident  that  a  hundred 
such  columnar  sections  may  be  made  along  the  line  of  any 
one  vertical  section;  but  that  where  the  beds  of  a  general 
section  are  very  regular  one  columnar  section  will  be 
enough  to  show  their  character,  order  and  thickness  along 
the  whole  line.  If,  however,  the  rocks  of  a  vertical  section 
be  variable  in  character  and  thickness  then  a  dozen  or  more 
columnar  sections  will  be  required  to  exhibit  these  varia- 
tions. Yet  many  geologists  are  satisfied  with  one,  and  the 
readers  of  their  reports  and  consulters  of  their  text-books 
are  left  to  gather  the  nature  of  such  irregularities  from 
descriptions  of  them  in  the  text. 

Now,  what  is  true  of  one  vertical  section  is  true  of  all. 
The  line  along  which  any  vertical  section  is  made  is  selected 
by  the  geologist  where  it  can  be  best  studied  in  his  district; 
where  a  river  has  exposed  the  rocks  for  a  mile  or  miles; 
where  railroad  cuttings,  lines  of  quarries,  ore  banks,  mine 
shafts  or  oil  borings  furnish  him  data  for  his  measurements. 
Such  sections  are  of  the  greatest  value,  and  are  in  fact  the 
foundation  of  all  accurate  geology.  But  these  natural  lines 
of  section  do  not  often  run  in  the  most  convenient  direction; 
run  sometimes  diagonally  across  the  strike  and  dip  of  the 
formations.  The}7  must  be  swung  around  to  cross  them  at 
right  angles,  if  the  true  structure  of  the  district  is  to  be 
exhibited.  Consequently  the  geologist  must  make  as 
many  such  sections  as  possible  in  all  parts  of  the  district. 
Some  will  be  short  and  some  long  according  to  circum- 
tances.  To  represent  the  whole  geology  of  the  district 
he  must  put  them  together.  He  constructs  thus  what  he 
calls  a  general  vertical  section,  and  gives  that  as  expressing 
a  summary  view  of  the  geology  of  the  whole  district.  This 
summary  view  will  certainly  give  some  general  idea  of  it. 
But  a  general  idea  of  the  geology  of  a  district,  however 
good  it  may  be,  will  be  mischievously  bad  in  one  respect, 
in  that  it  will  lead  people  who  are  not  judicious  field  geol- 
ogists to  believe  that  that  general  section  represents  accu- 
rately the  geology  of  each  and  every  portion  of  the  district. 
They  will  act  on  that  assumption.  They  will  apply  that 


32  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

general  section  to  the  discovery  of  minerals  in  parts  of  the 
district  where  local  facts  do  not  correspond  at  all  to  the 
general  section.  In  fact  nothing  has  tended  more  to  bring 
into  popular  disfavor  the  work  of  field  geologists  than 
the  serious  embarrassments  to  which  laymen  have  been  sub- 
jected in  trying  to  apply  the  general  section  of  a  district 
to  some  special  locality  in  which  they  are  personally  in- 
terested. 

What  has  just  been  said  has  greater  force  in  respect  to 
general  columnar  sections,  which  are  intended  to  furnish  a 
quick  and  easy  key  to  the  order,  character  and  thicknesses 
of  the  rock-beds  of  a  district.  Even  in  the  hands  of  an  ex- 
perienced geologist  such  general  columnar  sections  are 
dangerous  tools  to  work  with.  They  impose  upon  the  im- 
agination, and  through  the  imagination  upon  the  reasoning 
faculty.  They  seem  to  reveal  clearly  what  in  fact  they 
conceal ;  they  mystify  it,  distort  it,  and  change  the  truth 
into  positive  error.  They  give  the  impression  of  regularity 
in  geology;  whereas  irregularity  is  the  only  law  of  geology 
which  can  be  called  absolutely  universal. 

Even  the  experienced  geologist  is  strongly  tempted 
to  recognize  a  general  columnar  section  as  true  at  every  lo- 
cality. Only  with  an  effort  can  he  keep  in  mind  that  it  is  a 
fiction,  a  construction,  not  a  reality;  a  generalization;  a 
sort  of  dressed  up  official  representative  of  thousands  of 
facts  for  which  it  speaks,  but  the  various  natures  of  which 
it  cannot  correctly  express.  If  one  of  the  beds  of  any  such 
columnar  section  happens  to  be  20  feet  thick  at  one  end  of 
his  district  and  100  feet  thick  at  the  other  end  ;  or,  if  it  be 
found  to  measure  20  feet  at  one  point  and  100  feet  at  an- 
other— even  if  these  two  figures  be  known  to  represent  the 
thinnest  and  thickest  sizes  of  that  bed  within  a  given  dis- 
trict— the  columnar  section  will  either  say  that  the  bed 
varies  from  20  to  100  feet,  or  it  will  say  that  its  average 
thickness  is  60  feet.  These  are  the  two  plans  ordinarily 
adopted  in  constructing  a  columnar  section  ;  but  they  do 
not  relieve  it  of  its  mischievous  character.  For  in  the  first 
place  there  may  be  places  underground  to  which  no  one  has 
had  access  where  the  bed  may  not  exist  at  all.  or  where  it 


ON   GENERAL   SECTIONS.  33 

thickens  to  200  feet.  Should  a  shaft  be  sunk  or  a  borehole 
drilled  at  such  a  point  the  general  section  is  at  once  dis- 
credited, and  even  whatever  value  it  has  will  be  denied. 

But  even  if  the  geologist  has  been  able  to  discover  the 
greatest  thickness  which  the  bed  has  anywhere,  and  its 
thickness  at  that  place  amounts  to  100  feet,  it  may  be  an 
exceptional  and  purely  local  fact.  Perhaps  the  bed 
throughout  the  district  varies  little  from  20  feet.  To  say 
then  in  the  columnar  section  that  the  bed  varies  from  20 
feet  to  100  feet  gives  a  wholly  false  and  unpractical  de- 
scription of  it.  If  the  second  plan  be  adopted  and  the 
average  of  60  feet  be  marked  on  the  edge  of  the  column,  it 
becomes  a  false  guide  everywhere  in  the  district,  for  there 
may  not  be  a  single  locality  where  this  average  of  60  feet  is 
realized. 

What,  then,  is  to  be  done?  Shall  there  be  no  attempt 
made  to  exhibit  in  the  form  of  a  column  the  order,  char- 
acter and  /thickness  of  the  rock  formations  of  a  district  \ 
Shall  the  reader  be  left  to  manufacture  his  own  ideas  of  it 
from  a  confused  mass  of  detailed  descriptions  in  the  text  of 
the  report  ?  If  he  be  thus  left  to  his  own  devices  he  will 
undoubtedly  construct  some  general  columnar  section  for 
himself,  and  it  will  probably  be  a  worse  one  than  that  which 
the  wise  geologist  has  discarded. 

There  is  a  plain  road  out  of  the  difficulty.  A  typical 
columnar  section  should  be  substituted  for  the  so-called 
general  columnar  section. 

Among  the  many  local  columnar  sections  which  the  geol- 
ogist constructs  (along  his  numerous  lines  of  vertical  sec- 
tion), each  one  giving  the  precise  facts  at  the  place  where 
they  present  themselves  to  the  eye  for  examination  and  to 
the  hand  for  measurement,  there  will  always  be  one  or  an- 
other more  precise  and  more  complete  than  the  rest,  show- 
ing more  distinctly  the  order,  character  and  thickness  of  the 
beds  of  the  district,  arid  as  accurate  in  its  statement  of  the 
facts  as  any  of  the  rest.  'Such  a  columnar  section,  vouched 
for  in  all  of  its  details,  and  marked  with  the  name  of  the 
locality  where  it  was  studied  by  the  geologist  and  can  be 
studied  by  any  number  of  observers  who  choose  to  verify 
3 


34  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

the  accurateness  of  his  observations — such  a  columnar  sec- 
tion, rightly  called  typical,  is  at  the  same  time  good 
authority  and  of  practical  value.  It  leaves  nothing  to  the 
vague  imagination.  It  is  a  reality  to  be  depended  upon. 
It  will  serve  as  a  useful  guide.  It  stands  only  for  what  it  is 
worth.  It  makes  no  pretensions  to  general  truth.  It  says 
nothing  respecting  the  stratification  or  structure  at  other 
localities  in  the  district,  being  only  one  of  many,  all  differ- 
ent from  each  other;  and  it  can  be  referred  to  in  explanation 
of  similar  appearances  not  so  well  exposed  to  examination. 
Above  all,  it  will  enforce  upon  -the  mind  of  everyone  who 
uses  it  for  comparison  with  other  local  columnar  sections 
that  law  of  irregularity  or  variability  on  which  the  genius 
of  geology  must  forever  insist,  as  the  first  to  be  recognized 
and  profoundest  to  be  felt  of  all  the  laws  of  our  science — a 
law  that  cannot  be  too  often  or  too  earnestly  inculcated — a 
law  both  of  the  highest  theoretical  and  the  most  real  prac- 
tical character,  governing  both  our  calculations  respecting 
the  outspread  of  continental  formations  and  the  minutest 
details  of  our  mining  operations. 


THE   APPALACHIAN   SEA.  35 


CHAPTER   V. 

The  Appalachian  Sea. 

The  arrangement  of  land  and  sea  upon  the  surface  of  the 
globe,  with  which  geography  makes  us  familiar,  appears  to 
the  human  mind  to  be  fixed  and  unchangeable.  The  relig- 
ious traditions  of  mankind  have  taken  this  for  granted  and 
explained  the  creation  accordingly.  But  this  is  not  a  fact. 
By  the  fossil  forms  of  many  extinct  animals  and  vegetable 
creations  embedded  in  the  rocks  of  all  ages,  it  appears  that 
all  continents  have  been  formed  beneath  the  sea,  and  have 
emerged  from  it  into  the  air.  By  the  way  the  continental 
fossiliferous  formations  lie  one  upon  another  it  appears 
with  equal  plainness  that  the  lands  have  emerged  and 
been  submerged  alternately  many  times  in  the  course  of 
the  history  of  the  world.  But  when  the  bottom  of  the  sea 
is  lifted  into  the  air  the  water  which  covers  it  flows  away 
from  it,  lifting  the  general  sea  level  of  the  world  in  propor- 
tion to  the  amount  of  land  which  has  become  uncovered. 
The  lifting  of  the  general  surface  of  the  sea  resubmerges 
lands  which  were  previously  out  of  water.  The  crust  of 
the  earth  has  been  subjected  in  all  geological  ages  to  such 
movements,  and  such  movements  are  going  on  still;  move- 
ments both  upward  and  downward.  They  are  not  upward 
movements  of  the  land  and  downward  movements  of  the 
sea  bottom,  but  alternate  upward  and  downward  move 
ments  of  both  the  dry  lands  'and  of  the  ocean  bottoms. 
The  upward  movement  of  a  continent  draining  its  edge, 
lifts  the  sea  level  and  submerges  the  edges  and  low-lying 
plains  of  other  continents.  The  downward  movement  of 
one  continent  drawing  the  ocean  over  its  low-lying  lands, 
lowers  the  sea  level  and  causes  an  apparent  elevation  of 
other  continents;  but  the  elevation  is  only  apparent;  the 
ocean  coast  is  extended  outward  by  the  fall  of  the  sea  level;. 


36  GEOLOGICAL   SURVEY   OF    PENNSYLVANIA. 

submarine  banks  like  those  of  Newfoundland  and  off  the 
Alaskan  coast,  are  left  like  great  islands  exposed  to  the  air 
and  ready  to  receive  the  seeds  of  a  new  vegetation,  and  the 
immigration  of  new  races  of  animals  to  feed  upon  them. 

For  the  same  reason,  whenever  the  bottom  of  the  sea  has 
been  lifted  there  has  been  a  rise  of  the  sea  level  and  an 
overflow  of  the  lowlands  of  all  continents.  On  the  other 
hand  every  downward  movement  of  the  earth  crust  beneath 
the  ocean  has  lowered  the  sea  level  and  drained  the  coasts 
of  the  continents.  It  is  a  geological  speculation  unsup- 
ported by  sufficient  evidence  that  the  oceans  have  always 
been  oceans,  and  that  the  ocean  bottoms  have  always  been 
descending.  There  is  sufficient  evidence  to  the  contrary; 
and  such  evidence  is  afforded  in  the  clearest  manner  by  the 
geology  of  Pennsylvania.  For  many  ages  the  crystalline 
floor  kept  going  downward,  draining  the  sea  water  from  the 
rest  of  the  surface  of  the  world  and  exposing  to  the  air  more 
and  more  of  the  -  coasts  of  then  existing  continents.  At 
first  the  downward  movement,  if  not  sudden,  was  relatively 
swift,  and  a  deep  ocean  was  early  established  along  that 
part  of 'the  earth's  surface  now  occupied  by  our  Atlantic 
states  ;  but  this  is  not  certain. 

This  ocean  first  received  the  Cambrian  sediments,  and 
afterwards  the  Silurian,  Devonian  and  Carboniferous.  Its 
original  depth  may  be  imagined  from  the  fact  that  on  top 
of  15,000  feet  of  Cambrian  beds  lie  in  middle  Pennsylvania 
6,000  feet  of  lower  Silurian  limestone  (regarded  by  most 
geologists  as  a  deep  sea  deposit)*  and  6,000  feet  of  fine  sand 
and  mud-slate,  on  top  of  which  lie  30,000  feet  of  Upper 
Silurian,  Devonian  and  Carboniferous  strata. 

Now  if  this  Appalachian  ocean  had  been  established  at 
once,  by  a  sudden  drop  of  the  crust  of  the  earth  to  a  depth 
sufficient  to  receive  all  these  Cambrian,  Silurian,  Devonian 
and  Carboniferous  strata,  that  is  to  a  depth  of  7  or  8  miles, 
the  general  sea  level  of  the  world  would  have  been  lowered 
many  hundreds  of  feet.  But  we  are  forbidden  to  suppose 
a  sudden  movement  on  so  grand  a  scale.  But  whether 

*Bnt  of  this  assumption  I  ain  very  doubtful,  as  will  appear  in  the  Chapter 
on  Formation  No.  II. 


THE    APPALACHIAN    SEA.  37 

quick  or  slow,  such  a  downward  movement  of  one  part  of 
the  earth's  crust  should  in  all  probability  have  entailed  as 
a  consequence  a  corresponding  elevation  of  other  parts  of 
the  surface  of  the  globe,  parts  of  the  then  existing  ocean 
bottoms,  as  well  as  parts  which  were  already  dry  land. 

There  is  nothing  but  a  theory  to  oppose  the  supposition 
that  what  is  the  Atlantic  ocean  now  (or  a  portion  of  it)  was 
in  all  Palaeozoic  time  a  continent  exposed  to  the  erosion  of 
the  rainfall,  supplied  with  rivers,  and  bestowing  the  waste 
of  its  rocks  in  the  Appalachian  sea.  Its  smaller  rivers,  de- 
scending rapidly  from  its  highlands,  would  supply  conglo- 
merates; its  larger  rivers  meandering  from  its  back 
countries,  with  longer  and  more  gentle  currents,  would 
supply  the  slates  and  clastic  limerocks. 

It  is,  of  course,  impossible  to  decide  between  the  oppos- 
ing probabilities  of  a  faster  or  a  slower  rate  of  the  down- 
ward movement  which  established  the  Appalachian  sea 
basin.  All  we  can  say  is  that  the  great  limestone  deposits 
are  very  early  ;  and  supposing  them  deep  sea  deposits,  we 
must  conclude  that  the  establishment  of  a  deep  Appala- 
chian sea  basin  was  of  early  accomplishment;  that  the 
downward  movement  was  at  first  comparatively  rapid;  and 
that  it  continued  (perhaps  more  and  more  slowly)  to  the 
end  of  the  coal  age. 

The  two  thoughts  which  are  here  fundamental  to  the 
knowledge  of  our  Pennsylvanian  geology  are  these:  (1) 
that  what  was  the  continental  area  of  crystalline  rocks 
became  by  the  downward  movements  of  the  earth's  crust 
an  Appalachian  sea  basin  of  unknown  depth,  and  was  in 
the  course  of  the  Cambrian,  Silurian,  Devonian  and  Car- 
boniferous ages  so  completely  filled  up  as  to  become  at  last 
a  great  marsh  or  archipelago  of  marshes,  bearing  the  vege- 
tation of  the  coal;  and  (2)  that  this  whole  area  was  then 
lifted  high  into  the  air;  that  a  corresponding  contempo- 
raneous down  ward  movement  established  the  Atlantic  ocean 
or  parts  of  it,  as  the  thrust  which  elevated  the  Appala- 
chians came  from  that  direction;  and  that  submergence  of 
other  lands  of  the  world  must  have  been  occasioned  by  the 
general  rise  of  the  sea  level. 


38  GEOLOGICAL   SURVEY   OF  PENNSYLVANIA. 

All  this  took  place  in  the  Palaeozoic  times,  that  is  in  the 
first  great  geological  age  of  the  world  of  animal  and  vege- 
table life.  The  coal  measures,  which  were  the  last  deposits 
in  the  Appalachian  sea,  taken  as  a  whole,  is  inconceivably 
ancient  and  remote  from  the  present  day. 

A  second  division  of  geological  history  then  succeeded  : 
the  Mesozoic  or  Middle  age  of  animal  and  vegetable  life. 

Then  came  the  Kainozoic  (Cenozoic)  or  New  world  of 
animal  and  vegetable  life,  ending  with  the  appearance  of 
man. 

Each  of  these  three  ages  of  the  world's  geological  history 
has  had  its  own  series  of  continental  elevations  and  depres- 
sions; its  invasions  of  the  continent  by  the  ocean  and  the 
reappearance  of  land  surfaces  on  the  retreat  of  the  water 
into  the  sea  basins;  its  own  peculiar  sequence  of  sediments 
brought  by  rivers  {and  deposited  in  the  sea,  all  of  them 
preserving  in  their  mud  and  sand  layers  the  waste  of  suc- 
cessive forests,  and  the  dead  remains  of  genera  and  species 
of  animals. 

All  the  greater  mountain  ranges  of  the  world  are  com- 
posed of  such  sedimentary  rocks,  which  have  been  lifted  out 
of  the  ocean  into  the  air  in  successive  ages  since  the  de- 
posit of  our  coal  beds,  and  mostly  in  Mesozoic  and  Kainozoic 
times. 

Movements  on  so  grand  a  scale  must  have  altered  mate- 
i;ially  the  relation  of  lands  to  seas,  modifying  more  or  less 
the  geography  of  the  whole  earth's  surface.  Therefore,  I 
find  it  hard  to  believe  that  oceans  have  always  been  oceans, 
and  continents,  continents,  even  if  other  facts  than  those 
alluded  to  above  were  not  known  to  prove  the  opposite. 


THE   NAMES    OF   THE   FORMATIONS.  39 


CHAPTER  VI. 
The  Names  of  the  Formations. 

Everything  has  to  have  a  name.  It  makes  very  little  dif- 
ference what  name  is  bestowed  upon  it,  provided  that  name 
be  generally  accepted  and  is  different  from  the  name  of 
anything  else,  so  that  the  name  shall  always  stand  for  that 
one  thing  and  for  nothing  else.  In  science  great  pains  have 
been  taken  to  invent  names  which  signify  the  character,  or 
some  characteristic  feature,  of  the  nature  of  the  thing 
named.  But  in  a  science  like  geology,  which  includes  sev- 
eral sciences,  structural  geology,  chemical  geology,  fossil 
geology  (paleontology)  and  economical  geology  (mining 
engineering,  etc.)  different  geologists  will  each  one  look 
upon  a  rock  formation  with  that  particular  interest  which 
it  has  for  his  special  studies  or  work,  and  will  wish  to  name 
it  accordingly.  Geologists  in  different  regions  will  give  dif- 
ferent names  to  the  same  formation,  each  affixing  to  it  the 
title  of  some  locality  where  he  finds  it  best  exposed  to  view, 
most  easily  studied,  of  greatest  size,  or  most  valuable  for 
the  community.  Geologists  of  different  countries,  speak 
ing  different  languages,  have  given  many  different  names  to 
the  same  stratum  or  series  of  strata.  All  this  is  inevitable. 
No  international  congress  of  geologists  can  either  hinder  or 
help  it.  The  confusion  arises  out  of  the  multiplicities  and 
irregularities  of  nature  itself.  Those  who  wish  to  profit  by 
geological  investigations  and  discoveries  must  submit  to  the 
burden  of  geological  nomenclature  and  learn  all  the  names, 
even  if  they  choose  to  use  qnly  some.  It  is  impossible,  to 
macadamize  or  asphalt  the  highways  and  byways  of 
knowledge. 

All  our  state  geological  surveys  have  invented  names  for 
some  of  their  formations,  and  for  others  have  borrowed 
names  already  given  to  them  in  neighboring  states.  Geo- 


40  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

logical  formations  care  nothing  for  geographical  lines 
established  by  king's  charter  or  acts  of  congress.  They 
pass  underground  from  one  state  into  another.  The  geology 
of  southern  New  York  is  exactly  the  same  as  that  of  north- 
ern Pennsylvania.  The  geology  of  northern  New  Jersey 
passes  on  across  middle  Pennsylvania  into  Maryland  and 
Virginia.  Eastern  Ohio  and  western  Pennsylvania  share 
with  West  Virginia  the  same  beds  of  coal,  limestone  and 
iron  ore,  the  same  oil  and  gas  sands.  The  formations  ex- 
posed on  the  Juniata  are  exposed  on  the  Potomac,  and  their 
outcrops  extend  to  Alabama.  The  Brown  sandstone  and 
red  shale  belt  of  Bucks,  Montgomery,  Chester,  Lancaster, 
York  and  Adams  counties  is  continued  to  the  Dan  and 
Deep  rivers  of  North  Carolina  in  one  direction,  and  up  the 
Connecticut  valley  into  Vermont  in  the  other  direction. 
The  Philadelphia  gneisses  and  mica  schists  pass  on  without 
break  through  Delaware,  Maryland  and  east  Virginia  as 
far  as  Georgia.  The  South  mountains  of  eastern  Pennsyl- 
vania are  the  same  as  the  Highlands  of  New  Jersey  and 
New  York  ;  the  South  mountains  of  southern  Pennsylvania 
are  the  same  as  the  Blue  Ridge  of  Virginia. 

These  facts  are  positively  known  to  all  geologists  now  ; 
but  they  were  only  suspected  to  be  possibly  or  probably 
true  by  geologists  sixty  years  ago,  when  the  principal  state 
surveys  were  set  on  foot.  Hastily  to  give  the  same  name  to 
a  series  of  rocks  in  two  different  states  which  might  turn 
out  on  examination  to  be  two  distinct  series  would  have 
made  a  great  embarrassment ;  and  an  example  of  this  is  af- 
forded by  the  employment  in  our  Pennsylvania  reports  of 
the  name  "Potsdam  sandstone"  borrowed  from  Dr. 
Emmons'  survey  of  the  Champlain  district  in  northern  New 
York,  to  designate  the  "White  Spot"  rock  overlooking 
Reading,  Chicques  rock  at  Columbia,  the  quartzite  beds  at 
Mt.  Holly  Springs  and  Mont  Alto  in  Cumberland  and 
Franklin  counties,  and  the  North  Valley  hill  rock  at 
Downingtown  and  Norristown;  for  it  is  now  doubtful  if  all 
or  any  of  these  have  right  to  that  name. 

A  still  more  flagrant  instance  is  afforded  by  the  old  and 
standing  controversy  over  the  name  Taconic  System,  a 


THE   NAMES   OF   THE   FORMATIONS.  41 

name  which  may  justly  be  called  the  Nightmare  of  Ameri- 
can Geology,  from  which,  however,  we  are  happily  almost 
awakened. 

For  fear  of  thus  hampering  their  surveys  with  names  that 
might  become  popular  and  yet'  be  absolutely  false  and 
worse  than  useless  the  state  geologists  of  Pennsylvania  and 
Virginia,  the  distinguished  brothers  Henry  D.  and  William 
B.  Rogers,  refused  to  accept  the  names  of  the  formations 
adopted  for  New  York  by  the  four  principal  geologists  of 
that  state,  Mather,  Emmons,  Vanuxem  and  James  Hall, 
and  adopted  a  plan  of  numbering  the  great  formations  ac- 
cording to  their  order  of  superposition  from  below  up- 
wards; a  series  of  numbers  which  of  course  would  never 
change,  and  for  which  distinctive  names  might  be  after- 
wards substituted.  These  numbers,  from  I  to  XIII  (after 
wards  increased  to  XVII)  only  applied  to  the  rock  forma- 
tions of  three-fourths  of  the  state,  Silurian,  Devonian  and 
Carboniferous.  The  earlier  rocks  of  the  Crystalline  region, 
and  the  later  rocks  of  the  New  Red  or  Brownstone  region, 
all  of  them  in  southeastern  Pennsylvania,  were  left  unnum- 
bered. This  numbering  was  accomplished  in  1836  and 
1837. 

Between  that  time  and  1858,  when  the  "  Geology  of  Penn- 
sylvania" was  published,  the  brothers  Rogers,  who  were 
poets  as  well  as  geologists,  devised  a  series  of  names  which 
they  proposed  to  substitute  for  the  series  of  numbers,  and 
for  all  other  names  applied  by  foreign  and  domestic  geolo- 
gists to  the  Palaeozoic  formations,  considered  as  successive 
deposits  made  in  one  long,  great  geological  day  of  time  ;  a 
day  divisible  into  four  portions,  before  and  after  sunrise, 
before  and  after  sunset;  the  day  in  which  the  Lower  and 
Upper  Silurian,  Devonian,  Carboniferous  systems  of  the 
English  geologists  were  deposited.  But  the  Coal  Measures 
belonged  to  the  night  and  received  no  name  ;  or,  rather, 
were  allowed  to  retain  that  popular  appellation,  being  sim- 
ply Coal  Measures. 

No.  1,  at  the  base,  also,  was  simply  named  the  Primal 
sandstone;  Nos.  2,  3,  Auroral  and  Matinal ;  Nos.  4,  5,  6, 
Levant  (sunrise),  Scaletut  and  Premeridian;  No.  7,  M&ri- 


42  GEOLOGICAL   SURVEY    OF   PENNSYLVANIA. 

dian  or  noon;  Nos.  8,  9,  Cadent  an&Ponenl  (sunset) ;  Nos. 
10,  11,  12  Vespertine,  Umbral  and  Serai. 

All  these  names,  except  three,  are  long  since  forgotten. 
No  geologist  has  accepted  them  as  useful.  But,  curiously 
enough,  the  people  of  western  Pennsylvania,  led  by  the 
coal  prospectors  of  the  Allegheny  mountains,  adopted  the 
three  exceptions,  and  still  speak  of  the  Vespertine  sand- 
stone No.  X,  the  Umbral  red  shale  No.  XI,  and  the  Serai 
conglomerate  No.  XII.  Some  geologists  have,  therefore,  em- 
ployed them  in  local  reports;  and  they  will  continue  to  be 
used  occasionally  instead  of  the  newer  'names:  Pocono 
sandstone,  Mauch  Chunk  red  shale,  and  Pottsmlle  conglo- 
merate. 

When  the  geological  survey  of  the  state  was  reorganized 
in  1874,  and  county  reports  began  to  be  published,  it  was 
needful  to  adopt  names  for  the  rock  deposits.  The  old 
numbers  were  not  precise  enough;  the  fanciful  names  of 
1858  had  been  universally  ignored;  the  New  York  names 
had  come  into  universal  use.  These  last  therefore  were 
applied  to  the  formations  in  Pennsylvania,  and  others  of 
the  same  geographical  character  were  added  at  the  end  of 
the  list  where  Pennsylvania  had  higher  strata  than  any  in 
New  York. 

No.  1  was  called  Potsdam  sandstone. 

No.  2  included  the  Calciferous  sandstone,  Chazy  and 
Trenton  limestone. 

No.  3  included  the  Utica  and  Hudson  river  slates. 

No.  4  included  the  Oneida  conglomerate  and  Medina 
sandstone. 

No.  5  included  the  Clinton,  Niagara  and  Salina  shales. 

No.  6  was  the  Lower  Helderberg  limestone. 

No.  7  was  the  Oriskany  sandstone  and  Caudagalli  grit. 

No.  8  extended  from  the  Corniferous  and  Marcellus  up 
through  the  Hamilton,  Genessee,  Portage  and  Chemung. 

No.  9  was  the  Catskill  or  Old  Red  sandstone. 

No.  10,  not  being  named  in  New  York,  although  it  forms 
the  peaks  of  the  Catskill  plateau,  received  the  name  Po- 
cono gray  sandstone. 

No.  11,  Mauch  Chunk  red  shale. 


THE   NAMES   OF   THE   FOKMATIONS.  43 

No.  12,  Potts ville  conglomerate. 

No.  13,  Allegheny  river  coal  measures. 

No.  14,  Pittsburgh  (Lower  Barren)  measures. 

No.  15,  Monongahela  river  coal  measures. 

No.  16,  Washington  county  group. 

No.  17,  Greene  county  (Upper  Barren)  measures,  the 
highest  Palaeozoic  strata  to  be  found  in  Pennsylvania,  and 
possibly  belonging  to  the  last  or  Permian  age  of  that  era 
in  geological  time. 

Names  given  by  the  assistant  geologists  of  the  state 
survey  to  sub-divisions  or  important  local  beds  in  these 
formations  will  appear  in  the  chapters  devoted  to  their 
description. 

The  terms  Azoic,  Eozoic,  Palaeozoic,  Mesozoic,  Kainozoic, 
have  been  already  alluded  to  as  designating  the  successive 
grand  geological  ages  of  vegetable  and  animal  life  on  the 
planet.  It  is  not  intended  in  this  book  to  use  the  first  two 
with  any  dogmatic  sentiment,  in  view  of  the  current  con- 
troversies on  what  I  consider  a  very  unimportant  subject, 
namely,  the  precise  unification  of  geological  nomenclature. 
One  name  is  quite  as  good  as  another  provided  it  be  known 
to  what  it  applies,  and  provided  that  it  implies  no  false 
description  of  character. 

Azoic  or  No-Life  rocks  was  a  good  term,  first  applied 
by  Foster  and  Whitney  to  the  crystalline  and  semi-crystal- 
line rocks  of  the  Lake  Superior  region,  to  express  the  fact 
that  no  relic  of  either  vegetable  or  animal  life  had  yet  been 
discovered  in  them.  It  was  not  intended  to  assert  that 
these  rocks  never  had  had  fossil  seaweeds  or  shells  in 
them,  but  merely  that  nonesuch  had  ever  yet  been  discov- 
ered in  them.  It  is  not  only  probable  but  proved  that  fossil 
bearing  sediments  crystallize,  and  in  doing  so  obliterate  the 
fossil  forms  which  before  crystallization  must  have  been 
visible  enough.  The  term  Azoic  simply  tells  the  fact  that 
no  fossils  have  been  found  in  them.  The  objection  made 
to  it,  that  rocks  of  later  ages  may  suffer  this  change  and 
lose  their  fossils  is  not  practically  a  good  one,  and  for  this 
reason,  viz :  that  ninety-nine-hundredths  of  the  Azoic 
rocks  belong  to  the  oldest  geological  age  we  know  anything 


44  GEOLOGICAL   SURVEY    OF   PENNSYLVANIA. 

about;  therefore  Azoic  is  a  very  convenient  name  for  the 
oldest  formations,  whether  they  appear  at  the  surface  in 
our  southeastern  counties,  or  lie  at  great  depths  beneath 
the  rest  of  the  state. 

Archcean  is  however  a  much  better  terra,  invented  by 
Professor  Jas.  D.  Dana,  and  adopted  very  generally, 
almost  universally,  by  the  geological  craft,  because  it 
simply  means  the  oldest  rocks  known,  and  passes  by  the 
question  whether  they  ever  contained  fossils  or  not. 

Fundamental  gneiss  was  the  term  preferred  at  first 
by  English  geologists  because  it  expressed  the  general 
character  of  the  crystalline  consolidated  floor  on  which  all 
other  formations  have  been  built  up.  But  Dana's  name 
Archcsan  has  been  gradually  replacing  the  English  name 
even  in  England. 

Laurentian,  Sir  W.  E.  Logan's  name  for  the  Azoic, 
Archaean,  Fundamental  gneiss  floor  of  the  known  geological 
under- world,  has  been  very  generally  adopted  by  American 
geologists,  and  has  been  used  in  many  of  the  reports  of  the 
survey  of  Pennsylvania,  especially  in  Prof.  Prime's  reports 
on  Northampton  and  Berks  counties,  Mr.  C.  E.  Hall's 
reports  on  southern  Bucks,  Montgomery  and  Delaware 
counties,  and  Dr.  Persifor  Frazer's  reports  on  Chester,  Lan- 
caster, York  and  Adams  counties.  The  mountains  of  the 
Lower  St.  Lawrence,  Labrador,  Canada,  and  the  Adiron- 
dack region  of  northern  New  York,  show  the  floor  rocks  of 
the  world  on  the  grandest  scale. 

Pre-Cambrian  is  another  term  for  the  same  azoic,  archsean, 
fundamental,  Laurentian  rocks,  adopted  by  conservative 
geologists  who  recognize  how  little  we  know  of  them,  and 
how  uncertain  are  the  identifications  of  them  in  the  isolated 
and  far-separated  regions  where  they  appear  at  the  present 
surface  of  the  globe.  For  this  term  merely  states  that  they 
were  in  existence  when  the  first  Cambrian  or  Eozoic  sedi- 
ments were  deposited  upon  them  in  the  earliest  seas.  In 
this  sense  Pre-Cambrian  means  all  rocks  older  than  or  be- 
neath the  lowest  Cambrian  beds  which  contain  fossils.  But 
by  other  geologists  it  is  used  in  another  sense,  namely,  to 
signify  formations  which  show  themselves  rising  to  the  sur- 


THE   NAMES   OF   THE   FORMATIONS.  45 

face  from  beneath  the  Cambrian,  and  which  yet  may  not  be 
as  old  as  the  Laurentian,  but  intermediate  between  the 
Laurentian  and  the  Cambrian.  If  they  contain  fossils 
they  should  be  included  in  the  Cambrian.  If  they  do  not, 
they  are  Azoic  rocks,  but  yet  may  not  be  Laurentian. 

The  Huronian  system,  lirst  studied  by  Murray  on  the 
north  shore  of  Lake  Huron,  and  so  called  by  Logan  and 
Hunt,  of  the  Canada  survey,  was  supposed  to  hold  such  in- 
termediate place.  But  Irving  and  A.  Winchell  have  appar- 
ently proved  that  only  the  lower  portion  of  it  is  Pre-Cam- 
brian,  and  the  upper  portion  may  be  Cambrian,  although 
no  fossils  have  yet  been  found  in  it  by  which  alone  its  Cam- 
brian age  can  be  established.  In  Report  E  of  the  Pennsyl- 
vania survey  Dr.  T.  S terry  Hunt  has  used  this  name 
Huronian  in  describing  rocks  in  Adams  county;  and  Dr. 
Frazer's  sections  of  the  South  mountains  of  Cumberland 
and  Fayette  counties  give  them  a  Huronian  aspect.  On  the 
other  hand,  Walcott's  Cambrian  quartzites  seem  to  be  well 
represented  in  the  Mt.  Holly  (Papertown)  gap,  and  else- 
where between  that  and  the  Maryland  line.  But  no  fossils 
(except  ScolitTius)  have  as  yet  been  found  in  the  South 
mountains  ;  probably,  or  perhaps,  for  want  of  observers  suf- 
ficiently disciplined  by  the  study  of  Cambrian  areas  else- 
where to  detect  them.  The  Green  Mountain  rocks  of  Ver- 
mont are  called  by  T.  S.  Hunt  Huronian.  Of  the  White 
Mountain  hornblendic  gneisses  and  mica  schists  he  makes 
his  Montalban  system,  and  identifies  it  with  the  Philadel- 
phia belt ;  Montalban  being  after  and  above  Huronian. 
See  Report  E,  page  241. 

Eozoic  rocks  are  those  which  show  by  fossils  the  dawn 
of  life  on  the  planet.  It  is  a  convenient  phrase  which 
means  nothing  definite  and  it  is  synonymous  with  the 
term  Cambrian,  although  the  Eozoon  canadense  is  called  a 
Laurentian  fossil.  But  C.  E.  Hall  asserts  that  he  can  prove 
that  the  strata  which  contains  this  oldest  of  all  supposed 
animal  remains  in  the  rocks  of  the'earth  really  belong  to 
post-Laurentian  times.  At  all  events,  with  the  possible  ex- 
ception of  the  Canadian  Eozoon  canadense,  the  earliest  ani- 
mal remains  are  the  trilobites  and  shells  of  the  Lower  Cam- 
brian (once  called  Taconic]  rocks. 


46  GEOLOGICAL   SURVEY    OF   PENNSYLVANIA. 

Cambrian  is  Sedgwick's  English  name  for  a  great  series 
of  deposits  in  Wales,  Scandinavia,  Bohemia,  Spain  and 
elsewhere,  which  have  been  admirably  studied  by  Walcott 
and  others  in  eastern  New  York,  eastern  Massachusetts, 
New  Brunswick,  Newfoundland,  Georgia  and  the  Rocky 
mountains.  Its  three  divisions  of  Lower,  Middle  and 
Upper  are  characterized  by  what  are  called  the  Olenus, 
Paradoxides,  and  Olenellus  faunas,  or  groups  of  trilobites 
mixed  in  with  sea  shells  of  many  kinds,  sponges,  worms, 
sea  weeds,  etc.  With  the  old  controversy  between  Sedg- 
wick  and  Murchison  respecting  the  limits  of  the  Cambrian 
and  Silurian  systems,  practically  settled  by  the  publica- 
tions of  the  geological  survey  of  Great  Britain,  we  have 
nothing  to  do.  And  as  little  now  with  the  equally  pro- 
tracted and  ill-natured  controversies  over  Dr.  Emmons' 
Taconic  system,  now  happily  ended  by  discoveries  which 
turn  that  unfortunate  system  upside  down  and  distribute 
its  members  among  the  Silurian  and  Cambrian  formations. 
The  same  fate  has  befallen  Logan's  Quebec  group.  Neither 
of  these  too  famous  names  appear  in  the  reports  of  the 
Pennsylvania  survey,  as  far  as  I  can  now  recollect,  except 
that  certain  fossils  in  P.  4  are  quoted  as  occurring  in  the 
latter. 

Palceozoic  ropks  are  those  which  contain  the  remains  of 
the  ancient  living  beings  of  the  world,  vegetable  and  ani- 
mal, from  the  Cambrian  sea  weeds,  sponges,  worms  and 
trilobites  up  to  the  land  plants,  shells  and  reptiles  of  the 
Coal  age.  If  anyone  pleases  he  may  merge  the  Eozoic  in 
the  Palceozoic,  and  begin  the  system  at  the  bottom  of  the 
Cambrian  sediments,  calling  the  whole  Palceozoic.  Cam- 
brian is  a  more  definite  term  than  Eozoic,  and  quite  as  con- 
venient. The  fewer  names  the  better.  Until  their  discov- 
ery by  Walcott  three  years  ago  in  the  Trenton  limestone 
of  the  Colorado,  fishes  were  supposed  to  have  come  into  ex- 
istence in  the  Upper  Silurian  times.  New  discoveries  are 
constantly  carrying  back  the  first  appearance  of  one  or  an- 
other family  of  living  things  to  remoter  and  remoter  times. 
No  one  has  a  right  to  say  how  early  in  geological  history 
vegetables  and  animals  appeared.  "The  dawn"  of  life  re- 


THE   NAMES   OF   THE   FORMATIONS.  47 

cedes,  farther  and  farther  into  the  past.  The  word  Eozoic 
is  becoming  useless ;  the  term  Palaeozoic  will  always  be 
sufficient  to  embrace  it. 

Silurian  rocks,  originally  studied  by  Murchison  in 
Wales,  whence  their  name,  and  since  then  in  most  of  the 
countries  of  the  world,  were  early  recognized  in  New  York, 
and  there  classified  (in  ascending  series)  as  Potsdam,  Cal- 
ciferous,  Chazy,  Trenton,  Utica,  Hudson  river,  Oneida, 
Medina,  Clinton,  Niagara,  Salina  (at  first  Onondaga]  and 
Lower  Helderberg,  corresponding  to  the  Pennsylvania  num- 
bers I  to  VI. 

Devonian  rocks,  first  studied  by  De  la  Beche  and  Mur- 
chison in  southwest  England,  and  afterwards  in  Scotland 
and  other  parts  of  the  world,  received  in  New  York  the 
sub-division  names  (upwards)  Oriskany,  Upper  Helder- 
berg,  Marcellus,  Hamilton*  Genesee,  Portage,  Chemung 
and  Catskill,  corresponding  to  the  Pennsylvania  Nos. 
VIII  and  IX. 

The  Carboniferous  formations  in  Pennsylvania  are  (in 
ascending  order)  Pocono  ( Waverlyin  Ohio),  Mauchchunk, 
Pottsville,  Allegheny,  Pittsburgh,  Mono7igahela,  Wash- 
ton  county  and  Greene  county  groups,  the  last  two  being 
awkward  names  for  the  highest  palseozoic  rocks  in  the  state. 
An  unknown  additional  quantity  of  beds  having  been  re- 
moved by  erosion,  the  original  topmost  or  last  deposits  of  the 
Carboniferous  series  are  unknown.  This  is  the  same  as 
saying  that  the  exact  date  at  which  the  Appalachian  sea 
was  dried  by  the  elevation  of  the  Palaeozoic  continent  into 
the  air  is  not  indicated  by  any  now  remaining  layer  or 
layers  of  rock  in  the  region  of  southwest  Pennsylvania,  or 
elsewhere  in  the  state.  If  the  upward  movement  took 
place  within  the  limits  of  the  Permian  age  of  Europe,  then 
the  highest  strata  of  Greene  county  may  be  called  rem- 
nants of  the  Permian  formation.  But  geologists  on  both 
sides  of  the  Atlantic  are  disposed  to  classify  the  Permian 
strata  as  the  last  of  Paleozoic  age,  and  to  begin  the  great 
Mesozoic  age  with  the  Trias. 

The  Mesozoic  or  middle  life  time  of  the  world's  geological 
history,  as  we  know  it  on  the  surface,  began  with  that  vast 


48  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

catastrophe  which  produced  the  United  States  as  a  contin- 
ental area.  He  that  is  best  acquainted  with  the  phenomenon 
will  be  the  best  convinced  that  it  was  a  sudden  or  rapid 
movement,  a  genuine  cataclysm.  The  overthrust  faults  are 
of  themselves  alone  sufficient  to  prove  it.  A  belt  of  par- 
allel mountains,  as  high  as  any  that  now  exist  in  South 
America  or  Asia,  rose  into  the  air  along  a  line  extending 
from  the  St.  Lawrence  to  the  Q-nlf  of  Mexico,  passing 
through  Pennsylvania.  The  whole  Appalachian  sea  was 
drained  off  and  became  dry  land,  a  continental  area  of  coal 
measures,  much  of  which  has  since  then  been  carried  away, 
but  much  still  remains,  constituting  the  extensive  coal 
fields  of  the  present  time.  The  whole  rain  water  drainage 
was  reversed.  The  Palaeozoic  river  system  which  came 
from  the  east  disappeared,  and  a  new  Mesozoic  river  system 
began  to  dissolve  the  raw  continent  and  carry  its  undried 
strata  piecemeal  eastward  into  the  newly-created  basin  of 
the  present  Atlantic  ocean. 

The  Mesozoic  age  has  three  divisions,  during  which  were 
successively  deposited  the  Triassic,  Jurassic  and  Creta- 
ceous rocks.  These  again  are  subdivided  in  Europe  into 
Bunttr,  Middle  Trias,  Keuper,  RhcBtic  and  Lias;  Oolite, 
&c.;  Wealden,  Oreensand  and  Chalk.  With  most  of  these 
names  Pennsylvanian  geology  has  nothing  to  do.  Some  are 
local  English  or  German  names.  And  many  more  names  have 
been  invented  for  use  in  other  countries  of  Europe,  Asia 
and  Africa,  where  peculiar  fossil  plants  and  animals  of 
Mesozoic  times  have  been  collected  and  described;  ferns  of 
a  new  style;  trees  quite  different  from  those  that  made  the 
coal  forests;  crocodilian  land  reptiles;  winged  lizards,  the 
prototypes  of  birds;  reptilian  sea  serpents;  superb  whorled 
shellfish  (Ammonites)^  small  land  mammals  like  kangaroo- 
rats  and  ant-eaters;  fish  with  pointed  teeth  of  twisted  fibre; 
the  earliest  oysters,  &c. 

The  Mesozoic  age  was  probably  as  long  as  the  Palaeozoic, 
judging  by  the  thickness  and  variety  of  its  sediments,  and 
the  succession  of  its  living  creatures.  In  Bucks  and  Mont- 
gomery counties  Mr.  B.  S.  Lyman's  survey  makes  out  more 
than  22.000  feet  of  regularly  super-imposed  strata,  all  de- 


THE   NAMES   OF   THE   FORMATIONS.  49 

posited  in  its  earlier  and  middle  divisions.  To  this  must 
be  added  the  Cretaceous  or  greensand  marl  deposits  of 
southern  New  Jersey,  which  only  appear  in  Pennsylvania 
at  the  bend  of  the  Delaware  below  Trenton. 

New  Red  was  the  name  (borrowed  from  the  English)  at 
first  given  to  the  Mesozoic  belt  crossing  the  Delaware, 
Schuylkill  and  Susquehanna  rivers,  and  the  Maryland  state 
line. 

Trias  is  the  name  usually  given  to  it  in  the  survey  re- 
ports; and  by  this  name  the  system,  as  studied  by  the 
Hitchcocks  in  Massachusetts,  by  Cook  in  New  Jersey, 
and  by  Fontaine  in  Virginia,  is  now  commonly  known. 

RlKKtic  is  the  term  adopted  by  Fontaine  (in  his  U.  S. 
Geological  Survey  monograph  report  on  the.  fossil  Mesozoic 
plants  of  Virginia)  by  the  use  of  which  he  wishes  to  make 
more  precise  the  sub-division  of  Mesozoic  time  in  which  that 
vegetation  flourished. 

Newark  formation  is  the  name  used  by  the  New  Jersey 
Geological  Survey,  and  adopted  by  the  assistants  of  the  U. 
S.  Geological  Survey,  for  the  Trias  sandstone  formation  of 
Pennsylvania. 

The  Lias  and  Oolite  of  Europe  are  not  recognized  in  the 
Atlantic  seaboard  region  of  North  America. 

The  Cretaceous,  on  the  contrary,  is  well  represented, 
but  no  chalk  beds  are  known  this  side  of  the  Mississippi  river. 
It  contains  the  lower  two  of  the  three  greensand  marl  beds 
of  New  Jersey  and  Delaware,  the  third  or  uppermost  being 
placed  in  the  Tertiary.  Its  lowest  member  (the  English 
Wealden]  is  called  the  Potomac  formation,  and  its  upper  or 
greensand  member  the  Severn  formation,  by  the  U.  S.  geol- 
ogists working  in  Maryland  and  Virginia. 

The  KAINOZOIO  (Cenozoic)  TERTIARY,  Third,  New  Life  age 
of  geological  history,  produced  an  equally  vast  and  varied 
series  of  deposits,  named  by  Lyell  Ei.cene,  Miocene  and 
Pleiocene  (to  which  was  afterwards  added  Pleistocene]  to 
express  the  fact  that  the  species  of  plants  and  animals  now 
living,  all  of  them  new,  made  their  debut  upon  the  scene  in 
tliedawn  of  this  new  third  great  day  (Eo-cene  tertiary};  be- 
came more  numerous  in  Mio-cene  tertiary  times  ;  most 
4 


50  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

numerous  in  Pleio-cene;  and  most  of  all  numerous  in  the 
Pleisto-cene.  These  names,  except  the  last,  are  still  in 
common  use,  but  only  for  purposes  of  vague  and  general 
description,  or  in  references  where  knowledge  is  not  locally 
precise  enough.  They  do  not  much  concern  Pennsylvania, 
a  region  out  of  water  since  Mesozoic  times,  and  therefore 
destitute  of  those  Tertiary  sediments  which  (with  the  Creta- 
ceous) make  the  tide  water  plain  of  southern  New  Jersey, 
Delaware,  Maryland  and  other  Atlantic  and  Gulf  states. 

Pamurikey  (Eocene),  Chesapeake  (Miocene),  Appomatox 
(Pliocene  ?),  and  Columbia  (early  Pleistocene),  are  names 
given  to  Tertiary  sub-divisions  in  Maryland  and  Virginia 
by  the  U.  S.  Geologists.  The  PamunJcey  represents  the 
uppermost  (or  third  greensand  marl)  beds  of  New  Jersey. 
The  Chesapeake  diatom  beds  at  Fort  Monroe  are  1,000  feet 
thick.  The  Appomattox  gravel  loam  formation  is  the  same 
as  the  Bryn  Mawr  (400'  level)  high  gravel  of  the  Delaware 
county  Report  C  4.  The  Columbian  terraces  pass  up  the 
river  valleys  of  Pennsylvania  and  are  connected  with  our 
glacial  deposits,  which  are  usually  designated,  not  Tertiary, 
but  Quarternary. 

In  the  Tertiary  age  appeared  shrubs  and  trees  that 
flower  and  fruit,  and  animals  of  sea  and  land  that  suckle 
their  young,  herbivorous  and  carnivorous,  man  among  the 
number.  When  first  mankind  appeared  is  not  known;  nor 
when  the  dog,  the  ox,  the  sheep,  the  horse,  the  elephant. 
It  has  just  become  known  that  Leidy's  fossil  horse  of  Caro- 
lina was  not  a  modern  horse.  Mammoths  and  Mastodons 
were  not  the  modern  elephant.  No  fossil  ape  agrees  en- 
tirely with  man.  Yet  discoveries  year  by  year  have  been 
pushing  back  the  proven  existence  of  man  into  Tertiary 
times.  There  is  therefore  less  and  less  propriety  in  sep- 
arating the  age  of  man  from  the  Tertiary  (or  Kainozoic)age 
and  calling  it,  as  is  so  often  done,  the  QUAKTERNARY  or 
Fourth  age  of  the  world.  Yet  this  will  still  be  used  as  a  con- 
venient term  for  expressing  the  state  of  things  which  now 
exists,  and  be  especially  applied  to  alluvions,  or  river 
sands  and  gravels  and  clays  such  as  Philadelphia  is  built 
upon. 


THE   NAMES   OF   THE   FORMATIONS.  51 

The  Glacial  Age,  or  Age  of  Ice,  is  a  term  which  fre- 
quently occurs  in  this  and  other  geological  literature  of  a 
recent  date.  Its  use  began  when,  half  a  century  ago,  the 
great  Swiss  explorer  of  the  Alps,  Louis  Agassiz  of  Neuf- 
ohatel,  announced  his  theory  that  Europe  had  been  covered 
with  a  sheet  of  ice  just  previous  to  the  creation  of  mankind. 
When  he  settled  as  a  teacher  in  Harvard  College,  Cam- 
bridge, Mass.,  he  showed  that  all  New  England  had  been 
under  ice.  Since  1847  the  phenomena  of  the  glacial  epoch 
have  been  studied  by  Upham,  Carll,  Wright,  Lewis,  Cham- 
berlin,  Dawson,  Whitney  and  a  host  of  other  glacialists, 
over  all  North  America  ;  and  the  southern  edge  of  the  ice 
sheet,  the  terminal  moraine  of  the  continental  glacier,  has 
been  traced  for  over  2,000  miles  from  Cape  Cod  to  Mani- 
toba. Its  course  through  Pennsylvania  is  mapped  and 
described  with  many  illustrations  in  H.  C.  Lewis'  Report 
of  Progress  Z.  The  age  seems  to  have  been  double,  the 
first  ice  sheet  receding  and  the  second  ice  sheet  advancing, 
with  an  interval  of  vegetation  between  the  two.  In  Cali- 
fornia man  seems  to  have  been  living  before  the  first 
advance  of  the  ice.  In  other  parts  of  America  man  and 
the  mastodon  lived  together  as  in  Europe  and  Asia  man 
and  the  mammoth  lived  together  in  glacial  times. 

The  cause  of  the  prevalence  of  ice  in  the  glacial  age  is 
still  a  matter  of  contention;  but  the  facts  have  been  verified 
beyond  controversy  and  are  accepted  by  all.  Many  of  the 
details  are  still  to  be  worked  out;  but  the  general  theory  is 
well  established. 

Now  granting  that  such  physical  operations  as  the 
evaporation  of  the  sea  water  and  the  condensation  of  snow 
upon  highlands,  to  form  ice  in  favorable  situations,  have 
been  regular  from  the  beginning  of  geological  time,  it  is 
reasonable  to  search  for  evidences  of  previous  and  far  more 
ancient  glacial  epochs  ;  and  such  evidences,  in  the  shape  of 
moraine  blocks  and  scratched  rock  surfaces,  have  been 
found  in  England,  in  India  and  in  South  Africa.  Prof.  Kerr 
thought  he  found  such  in  his  survey  of  North  Carolina. 
All  these  evidences  are  localized  in  the  last  Permian  or  first 
Triassic  rocks.  None  have  been  found  in  Pennsylvania; 


52  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

and  foe  good  reason.  There  must  have  been  a  glacial  age  im- 
mediately following  the  rise  of  the  great  anticlinal  mountains 
of  our  state  out  ol  the  Appalachian  sea  into  the  upper 
regions  of  the  atmosphere  to  a  height  of  more  than  five 
miles  above  present  sea  level,  and  to  a  height  of  perhaps 
eight  miles  above  the  bottom  of  the  alternate  synclinal 
valleys.  Even  if  the  climate  of  the  40th  parallel  of  north 
latitude  in  the  coal  age  was  tropical,  the  tops  of  the  uplifted 
anticlinal  ridges  must  have  been  immediately  covered  with 
perpetual  snow,  like  Killimanjaro  under  the  equator  in 
eastern  Africa,  the  volcanoes  of  Peru,  and  Mount  Whit- 
ney overlooking  the  valley  of  death  in  Arizona,  where  the 
thermometer  stands  at  110°  F.  in  the  shade.  The  heads  of 
the  synclinal  valleys  doubtless  made  good  circuses  for  the 
manufacture  of  neve ;  and  of  course  glaciers  flowed  down 
the  synclinal  valleys,  and  produced  mountain-meal  and 
moraines.  The  meal  was  not  white  like  that  made  now 
from  Jurassic,  Cretaceous  and  Tertiary  slopes  of  the  Alps, 
but  dark  grey  and  red  from  the  Carboniferous  and  Devon- 
ian ;  and  therefore  the  deposits  of  Triassic  age  in  Pennsyl- 
vania, brought  down  by  the  Susquehanna  and  Delaware 
from  that  ancient  highland,  are  mostly  red  or  reddish.  But 
the  long  continuance  of  erosion  has  reduced  the  highland 
to  its  present  level  of  only  1,500  to  2,500  feet  above  tide 
level,  and  swept  away  every  trace  of  that  local  glacial  state 
of  things. 

Alluvial  deposits  are  those  river  gravels,  sands  and  clays 
which  have  been  deposited  in  the  now  existing  valleys, 
mostly  since  the  retreat  of  the  ice,  and  up  to  the  present 
date. 


HIGHLAND   GNEISS.  53 


CHAPTER  VII. 

The  Earliest  Archcean,    Azoic,    Highland,  Laurentian, 
Fundamental  gneiss  or  crystalline  schists. 

In  the  beginning  of  time  as  known  by  the  science  of 
geology,  the  heavens  were  as  they  are  to-day;  the  planets 
encircling  the  sun,  comets  coming'  and  going,  the  moon 
a  trifle  nearer  to  the  earth,  the  sun  a  little  farther  off  but 
shining  with  somewhat  more  fervor  and  brilliancy. 

The  earth  was  already  in  extreme  old  age,  having  long 
before  then  shrunk  almost  to  its  present  size  and  globular 
shape,  by  slow  condensation,  from  a  gaseous  to  a  liquid 
state,  and  got  itself  encrusted  with  a  rind  of  solid  rock, 
which  no  longer  shone  with  a  dull  red  light  of  its  own,  but 
reflected  into  space  the  white  radiance  of  the  sun. 

The  surface  of  the  earth  was  no  longer  hot  enough  to 
keep  all  the  water  of  the  planet  in  a  state  of  vapor  in  the 
surrounding  atmosphere;  descending  in  local  deluges  of 
sour  rain  to  boil  upon  the  rocks  and  dissolve  apart  their 
mineral  elements,  sweep  them  into  hollows,  and  there  leave 
them,  while  it  sprang  aloft  as  steam  to  rejoin  the  universal 
canopy  of  cloud.  All  this  had  taken  place  before  the 
flrst  age  of  which  we  have  any  geological  monuments,  and 
is  only  known  to  God  and  Dr.  Sterry  Hunt,  who  has  de- 
scribed it  magnificently  in  his  Chemical  Researches. 

When  the  monumental  history  of  geology  commences, 
the  crust  of  the  earth  had  become  as  fixed  and  rigid  as 
the  attraction  of  the  sun  and  moon  and  Jupiter  would 
permit.  It  still  bent  and  groaned  and  quaked  indeed,  as 
the  globe  turned  on  its  axis  beneath  thier  irresistible 
influence;  but  now  only  enough  to  strain  open  great  vol- 
canic vents,  from  which  flames  and  smoke  and  ashes  were 
ejected,  to  fall  in  beds  of  tufa  over  large  areas  ;  and  from 


54  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

other  apertures  great  streams  of  lava  poured  themselves 
upon  the  surface  of  the  lands,  or  spread  themselves  upon 
the  bottom  of  the  sea.  Earthquakes  were  then  in  the 
common  order  of  events,  and  changes  of  sea  level  rapidly 
accomplished.  The  air  was  moist  and  murky,  the  ocean 
warm,  the  continent  a  bare  and  rocky  desert,  ridged  and 
rugged,  with  no  sign  of  future  life.  No  sound  disturbed 
the  silence  of  the  air,  except  the  noise  of  water-falls,  of 
rain,  or  breaking  waves,  the  roar  of  a  volcano,  the  crash  of 
a  crumbling  cliff,  or  the  explosion  of  a  descending  meteor. 
But  snow  had  begun  to  cover  the  peaks  of  Alpine  mount- 
ain ranges,  and  old  thousand- branched  rivers  raged 
through  chasms  between  them,  fretting  their  sides  into 
valleys,  and  sweeping  the  rabble-rout  of  that  perpetual 
destruction  into  all  low  places  where  the  waters  lay  eager 
"to  receive  and  spread  it  out  in  beds.  There  was  no  more 
•hurry  nor  appearance  of  confusion  then  than  now  ;  only  a 
anore  earnest,  rapid  and  efficient  operation  of  tearing  down 
t)n  land  and  building  up  at  sea  ;  for  Nature  was  leveling 
her  grounds  and  getting  ready  to  plant  and  house  her 
future  progeny.  Nor  can  we  find  out  with  all  our  search- 
ing and  calculation  how  many  centuries  or  milleniums  of 
human  and  solar  years  that  first  great  No-life  age  of  purely 
physical  preparation  lasted. 

Of  that  Archaean,  oldest,  Azoic,  or  No-life  age  we  know 
nothing  except  the  kinds  of  rock  which  bear  its  date. 
These  appear  at  the  present  surface  of  the  earth  only  here 
and  there,  in  limited  districts,  far  apart  from  one  other,  in 
Canada  and  New  England,  in  the  Blue  Kidge,  in  the  Rocky 
mountains,  in  Brazil,  in  Scotland  and  Scandinavia  and 
Bohemia,  in  the  Ural  mountains,  in  Upper  Egypt,  the  pen- 
insula of  Mt.  Sinai  and  elsewhere ;  but  so  surrounded  and 
overlaid  by  the  deposits  of  aftercoming  ages  that  no  con- 
nected account  can  be  given  of  their  origin  and  general  dis- 
tribution; nor  can  the  geography  of  that  time  be  mapped 
out ;  not  even  where  was  land  and  where  sea  ;  nor  where 
the  mountains  rose,  nor  where  the  rivers  ran,  nor  the  di- 
rection of  the  great  sea  currents,  nor  the  location  of  vol- 
canic vents.  So  that  nearly  all  that  has  been  printed  in 


HIGHLAND    GNEISS.  55 

geological  books  respecting  these  things  may  be  safely 
regarded  as  pure  speculation,  and  uncommonly  daligerous 
for  any  one  to  believe  who  wishes  to  gather  only  the 
knowledge  that  is  real,  and  prefers  expectant  ignorance  to 
any  satisfaction  to  be  drawn  from  unsubstantial  opinions. 

What  is  certainly  known  about  the  oldest  rocks  may  be 
set  down  in  a  few  sentences. 

First,  that  they  underlie  all  the  formations  in  which 
appear  traces  of  vegetable  and  animal  life,  and  therefore, 
that  they  constitute  the  underground  bottom  floor  of  all 
countries  wherever  life-rocks  occupy  the  surface 

Secondly,  that  they  differ  from  the  life-deposits  of  suc- 
ceeding ages  by  being  crystalline  instead  of  granular;  as 
loaf-sugar  differs  from  ground  sugar,  or  wheat  from  grist 
or  flour,  or  wood  fibre  from  paper  pulp,  or  a  stone-slide  at 
the  head  of  a  river  from  the  sand  banks  at  its  mouth.  For 
the  life-rocks  of  subsequent  times  have  been  made  out  of 
the  frost-fractured  and  water-worn  no-life  rocks  of  the 
ground  floor  of  the  world;  and  show  this  derivation  in  the 
fact  that  the  original  crystals  may  still  be  detected,  with 
their  points  and  edges  worn  off,  and  their  prisms  changed 
into  globules  or  rounded  grains. 

Thirdly,  that  they  differ  among  themselves  by  the  cir- 
cumstance that  some  are  coarsely  crystalline  (like  the 
porphyries  and  graphic  granite),  while  others  are  so  finely 
crystalline  (like  many  of  the  quartzites,  felsites,  diorites, 
dolomites  and  micaceous  gneisses)  that  their  crystalline 
constitution  must  be  looked  for  with  a  magnifying  glass. 

Fourthly,  that  they  differ  among  themselves  in  another 
particular,  namely,  that  some  are  plainly  stratified  or 
bedded,  others  foliated  or  split  into  millions  of  thin  leaves, 
and  others  subdivided  only  into  masses  by  occasional 
cracks;  and  these  three  principal  varieties  seem  to  repre- 
sent, 1st,  those  which  were  deposited  in  water  and  after- 
wards crystallized;  2d,  those  which  were  ejected  from  vol- 
canoes as  dust  or  ashes  and  afterwards  crystallized;  and  3d, 
those  which  flowed  up  from  the  interior  of  the  earth  as 
lava  and  crystallized  on  cooling.  But  there'is  such  variety 
in  each  kind,  and  so  much  discussion  among  microscopical 


56  GEOLOGICAL   SURVEY    OF   PENNSYLVANIA. 

geologists  over  these  different   varieties,  as  to    leave  the 
whole  subject  still  in  doubt  and  confusion. 

Fifthly,  that  they  may  all  be  broadly  grouped  under  two 
heads  in  respect  of  their  chemical  constitution.  For  the 
crust  of  the  earth  is  almost  entirely  made  out  of  three  ele- 
ments, two  metals  and  one  gas  ;  the  two  metals  being  sil- 
icon and  aluminium,  and  the  gas  being  oxygen.  The 
other  elements  known  to  chemists  play  subordinate  parts. 
First,  the  union  of  oxygen  with  silicon  makes  silica 
(quartz,  rock  crystal,  opal,  <&<?.);  and  the  union  of  oxygen 
with  aluminium  makes  alumina  (corundum.}  Then,  the 
union  of  silica  and  alumina  makes  glass  (fe  spar,  porcelain 
clay,  &c.).  Therefore,  the  ball  of  the  earth  may  be  said 
to  have  a  glass  coat  or  crust,  which  may  be  likened  to  the 
slag  of  an  iron  furnace;  not  pure  transparent  glass,  but 
glass  mixed  with  earths  and  metals  of  various  kinds  in 
smaller  proportions,  lime,  magnesia,  soda,  potash,  iron, 
manganese.  Now  in  the  chemical  union  of  silica  with  al- 
umina the  silica  plays  the  part  of  an  acid,  and  the  alumina 
plays  the  part  of  a  base,  being  the  fundamental  element 
or  basis  of  the  union.  Hence  all  rocks  which  have  more 
alumina  than  the  silica  can  unite  with  are  called  basic 
rocks;  and  thes.e  which  have  too  much  silica  for  the  amount 
of  alumina  present  are  called  acid  rocks.  But  as  silica 
unites  in  the  same  way  with  lime,  magnesia,  soda,  potash 
and  iron,  which  general  accompany  alumina,  a  great 
surplus  of  silica  was  required  in  the  creation,  and  was 
amply  supplied;  so  that  a  considerable  portion  of  it 
remains  by  itself  in  the  form  of  quartz  (rock  crystal). 
This  is  seen  scattered  through  rock  in  brilliant  transparent 
crystals ;  especially  in  granite.  The  rest  of  the  silica  is 
united  with  the  alumina  in  shining  waxy  crystals  (felspar) 
of  various  colors.  When  these  quartz  crystals  and  these 
felspar  crystals  make  up  the  whole  of  a  rock  it  is  called  a 
syenite.  But  when  iron  is  present,  then  the  rock  shows 
millions  of  glittering  spangles,  exceedingly  thin  films  of 
mica  (white  or  black),  and  the  rock  is  called  a  granite. 
With  other  combinations  the  iron  forms  black  prisms  of 
hornblende,  and  the  rock  is  called  hor tiblendic  granite. 


HIGHLAND   GNEISS.  57 

If  the  silicate  of  alumina  has  separated  from  the  quartz 
by  slow  cooling  into  great  crystals  of  felspar,  the  rock  is 
called  a  porphyry  ;  and  when  a  small  mixture  of  iron,  &c. 
gives  the  felspar  a  rose  tint,  red  poryJiyry.  From  these 
few  specimens  of  variation  it  may  be  easily  seen  what 
infinite  variety  of  grain  and  color  the  Azoic  rocks  present, 
although  they  are  all  mere  glass. 

Sixthly,  that  the  Azoic  formations  are  enormously  thick. 
But  their  true  thickness  has  not  been  accurately  measured 
in  any  country;  nor  can  it  be  measured;  because,  being  the 
oldest  known  rocks,  they  have  suffered  more  than  all  from 
waving,  compressing  and  overturning  movements  in  the  flex- 
ible earth  crust,  both  in  their  own  time  and  in  all  succeed- 
ing ages ;  so  that  at  no  place  in  any  country  can  they  be 
seen  lying  flat;  but  always  uptilted,  at  all  angles,  and  so 
folded  and  twisted,  so  cracked,  veined  and  faulted,  as  to 
defy  measurement,  and  make  it  often  impossible  to 
decide  which  is  top  and  which  is  bottom  to  them;  so  that 
their  order  of  arrangement  is  in  dispute  ;  and  some  experi- 
enced geologists  declare  that  we  must  be  satisfied  to  con- 
sider them  as  a  whole,  without  attempting  to  subdivide 
them  into  series  of  formations,  with  separate  dates  and 
names.  This  opinion,  however,  is  not  shared  by  most  geol- 
ogists, and  various  methods  of  arranging  them  are  in  vogue, 
under  such  names  as  Laurentian,  Norian,  Arvonian, 
ffuronian,  Montalban,  DimUian,  Pebidian,  &c.,  which 
may  be  found  in  text-books  and  other  writings  of  geology, 
but  which  have  no  real  meaning  except  in  the  districts 
where  they  were  first  invented,  and  not  in  all  cases  a  cer- 
tain meaning  even  there.  For  when  the  supposed  or  imag- 
ined order  of  the  Azoic  rocks  in  one  region  or  country  is 
applied  to  another  region  no  one  is  satisfied  with  the  result, 
and  some  other  order  must  be  invented  to  suit  each  local 
exhibition.  If  all  the  Azoic  rocks  were  truly  and  certainly 
stratified,  or  deposited  as  successive  layers  of  sand  and 
mud  in  water,  and  afterwards  crystallized  and  folded  up, 
there  would  be  some  chance  of  learning  their  disposition, 
and  getting  somewhat  near  to  the  real  thickness  of  the 
whole.  But  so  many  lava  and  volcanic  ash  beds  lie  among 


58  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

them,  and  such  huge  and  numerous  outbreakings  of  fluid 
rock  from  the  earth's  interior  through  and  between  them 
have  happened,  and  whatever  bedding  they  may  once  had 
is  so  obscured  by  foliation  arid  cleavage  planes  produced  by 
pressure,  that  taking  all  these  things  together  into  consid- 
eration the  wise  geologist  will  be  cautious  of  forming  an 
opinion  where  Nature  seems  resolved  to  leave  us  in  the 
dark.  This  much  alone  is  evident,  that  the  Azoic  rocks  are 
thick  enough  to  make  whole  mountain  ranges.  In  New 
Hampshire  and  Vermont  they  are  imagined  to  be  77,000 
feet  thick.*  In  the  Lake  Superior  region  where  six  sub- 
divisions of  them  have  been  devised,  the  upper  five  are 
thought  to  measure  more  than  18, 000  feet,  f  In  Pennsylva- 
nia, where  the  Schuylkill  cuts  through  a  part  of  them  for 
twenty  miles  from  Conshohocken  to  Philadelphia,  they  seem 
to  measure  at  least  15,000  feet,  with  an  unknown  additional 
quantity  beneath  the  valley  of  the  Delaware  river. 

Lastly,  that  all  the  great  magnetic,  specular  and  titani- 
ferous  iron  ore  beds,  beds  of  plumbago,  beds  of  crystalline 
phosphate  of  lime,  and  beds  of  red  jasper  are  of  azoic  age, 
but  not  in  the  oldest  series  of  its  rocks.  To  the  same  age 
belong  the  tin  ores  of  Cornwall,  New  Hampshire  and  Da- 
kota, the  corundum  and  beryl  beds  of  North  Carolina,  the 
mother  rocks  of  the  Brazilian  diamonds,  and  the  turquoise 
rocks  of  Mt.  Sinai.  The  serpentine  beds  of  the  great  lakes 
are  of  that  age;  probably  those  of  the  Alps  and  Appenines; 
perhaps  those  of  southeastern  Pennsylvania  and  Mary- 
land; but  those  of  Northampton  county  in  our  state,  and 
others  elsewhere  may  be  of  later  age4  The  so-called  Eozoon 
serpentine-limestone  beds  of  Canada,  Massachusetts  and 
Bohemia  are  in  azoic  districts;  and  many  groups  of  crsytal- 
line  limestone  strata  of  great  thickness  were  deposited 

*Desc.  of  Geol.  Sect,  crossing  N.  H.  and  V.,  by  Prof.  C.  H.  Hitchcock, 
Concord,  N.  H.,  1884,  p.  33. 

fN.  H.  Winchell,  in  Amer.  Naturalist,  Oct.,  1884.  R.  D.  Irving  in 
Presidential  address  to  Wise.  Acad.  Sci.,  Dec.  30,  1884;  and  Art.  33,  Amer- 
J.  of  S.,  March,  1885. 

JGeol.  Hist.,  Serpentiees,  T.  S.  Hunt.  Trans.  R.  S.  Canada,  Vol.  I,  Sec. 
IV,  Montreal,  1883.  But  see  T.  D.  Rand,  Proc.  Acad,  N.  S.  Phila.,  March, 
1890,  page  95. 


HIGHLAND   GNEISS.  59 

before  the  appearance  of  life  upon  the  planet,  unless  the- 
theory  of  their  organic  origin  be  adopted,  or  the  old 
exploded  theory  of  their  igneous  origin  be  so  dressed  up 
as  to  be  again  presentable. 

From  what  has  been  said  above  it  will  appear  that  our 
knowledge  of  the  earliest  chapter  of  geological  history  rep- 
resented by  the  Azoic  or  No-life  rocks  amounts  onj.y  to 
a  confused  perception  of  great  events  taking  place  at  the 
consolidating  surface  of  the  globe  through  a  great  length 
of  time,  without  being  able  to  tell  with  any  certainty  what 
those  events  exactly  were,  or  how  they  were  brought  about. 
Fire  and  water  were  cooperating  in  the  slow  preparation 
of  continents  and  oceans  capable  of  sustaining  every  form 
of  life  which  should  afterwards  appear.  The  atmosphere 
was  gradually  clearing  itself.  The  sun  went  on  contracting 
its  dimensions.  Of  the  moon  we  know  nothing;  it  may 
have  grown  cold  and  lifeless  long  before,  or  not  until  after- 
wards. 

But  when  this  picture  of  apparent  vast  obscurity  and 
confusion  is  carefully  studied,  as  it  has  been  for  many 
years,  and  more  closely  now  than  ever,  by  a  host  of  shrewd 
geologists,  provided  with  three  kinds  of  apparatus  for  in- 
vestigation, the  pickaxe,  the  microscope  and  the  retort,  in- 
numerable items  of  positive  knowledge  come  to  view,  and 
the  geology  of  the  Azoic  rocks  takes  practical  shape  and 
may  be  relied  on  as  a  useful  guide  in  the  affairs  of  human 
business. 

Some  steps  even  have  been  taken  towards  the  solution  of 
theoretical  questions  of  age  and  order  of  arrangement. 
Thus  rocks  supposed  to  be  sedimentary  have  been  shown 
by  a  study  of  their  microscopic  crystals  to  be  volcanic 
ashes,  *  or  by  their  banded  structure  to  be  lava  flows,  f 
or  by  the  shape  and  connection  of  their  atoms  to  be  crys- 
talline masses  crushed  into  the  form  of  laminated  schists. :{: 
On  the  other  hand,  iron  ore  deposits  once  assuredly 

*The  felsites  and  their  associated  rocks  north  of  Boston.  J.  S.  Diller, 
Bull.  Mus.  C.  Z.,  Harvard  College,  Cambridge,  1881,  Vol.  VII,  p.  168. 

fThe  Azoic  system,  J.  D.  Whitney  and  M.  B.  Wadsworth,  Bull.  Mus- 
C.  Z.,  Vol.  VII,  1884. 

f  Prof.  Bonney 's  papers  on  the  rocks  of  the  Alps. 


60  GEOLOGICAL   SURVEY    OF   PENNSYLVANIA. 

taken  to  be  volcanic,  have  been  found  by  mining  operations 
to  be  true  sedimentary  beds,  deposited  in  water, 'and  prob- 
ably in  a  manner  similar  to  the  beds  of  magnetic  iron  sand 
now  forming  on  the  northern  shore  of  the  Gulf  of  St.  Law- 
rence and  along  the  coast  of  California. 

The  study  of  the  Azoic  rocks  in  many  countries  has  been 
conducting  geologists  gradually  to  the  conclusion  that, 
however  difficult  it  may  be  to  classify  them  in  regular  order 
of  time  or  superposition,  yet  that  as  a  whole  they  separate 
themselves  naturally  and  broadly  into  a  lower,  older,  more 
massive,  darker  Tiornblendlc  series,  and  an  upper,  younger, 
more  thinly-bedded,  lighter-colored  micacious  series,  con- 
taining the  most  ancient  iron  ore,  serpentine  and  marble 
beds.  The  older  series,  if  such  it  be^is  known  in  Europe  as 
the  Fundamental  gneiss,  and  in  America  as  the  Laurentian 
system.  The  upper  series  is  often  called  the  Newer  gneiss 
by  those  who  feel  unwilling  or  unable  to  subscribe  to  any 
universal  Huronian  theory,  or  who  suspect  that  the  whole 
or  parts  of  it  may  possibly  turn  out  to  be  more  recent  sed- 
iments disguised  by  recrystallization,  an  idea  once  popular, 
then  falling  into  disfavor,  and  now  struggling  to  regain  its 
reputation  against  vehement  and  powerful  protestations. 

But  just  here  the  Story  of  the  Creation  halts  to  ask  itself 
three  questions :  1st,  Whether  there  could  have  been  any 
serious  interruption  of  events  between  the  Older  and  the 
Newer  Gneiss  ;  2d,  Whether  there  could  have  been  a  gen- 
erar  deposit  of  the  same  kind  of  Newer  Gneiss  upon  the 
surface  of  the  earth  to  such  an  extent  as  to  make  it  now 
recognizable  in  places  so  far  apart  as  the  opposite  shores  of 
America,  or  the  opposite  sides  of  the  Atlantic;  and,  3d, 
Whether,  if  life  had  then  commenced  upon  the  planet,  all 
traces  of  it  could  have  been  completely  lost,  the  closest  ex- 
amination failing  to  detect  them.  Until  these  three  prime 
questions  are  answered  a  satisfactory  history  of  the  Azoic 
age  or  ages  can  by  no  means  be  written  ;  nor  can  Azoic 
geology  be  other  than  an  unconnected  description,  an 
unclassified  catalogue  of  the  rocks  (with  their  included  min- 
erals) which  occupy  isolated  areas  of  the  earth's  surface, 
projecting  through  the  sediments  of  later  times. 


HIGHLAND   GNEISS.  ,        61 

The  terms  Laurent ian  and  Huronian  are  local  and 
peculiar  to  the  Canada  survey.  The  range  of  mountainous 
country  which  extends  from  Labrador  westward  across  the 
Snganay  and  Ottawa  rivers,  north  of  the  river  St.  Lawrence, 
and  Lake  Superior,  is  made  up  chiefly  of  massive  reddish 
and  grayish  hornblendic  granite  and  gneiss  rocks,  and  with 
great  beds  of  crystalline  limestone  in  the  upper  part  of  the 
series,  the  whole  being  called  the  Laurentian  System. 

To  the  south  of  this  mountain  land,  along  the  north 
shore  of  Lake  Huron  and  extending  westward  through  the 
Marquette  iron  region  into  Wisconsin,  appear,  finely  ex- 
posed to  view,  beds  of  vitreous  quartzite,  red  and  white, 
beds  of  conglomerate,  holding  pebbles  of  jasper,  chert  and 
limestone,  beds  of  chloride  slate,  beds  of  reddish  limestone, 
beds  of  lava  of  various  kinds  and  volcanic  glass,  beds  of  sul- 
phuret  of  copper  ore,  and,  in  the  western  part,  vast  beds  of 
jasper  and  specular  iron  ore,  the  whole  being  called  the 
Huronian  System. 

The  Laurentian  system  is  directly  connected  by  the 
Thousand  Island  rocks  with  the  great  Adirondack  mountains 
of  northern  New  York.  The  Adirondack  rocks  are  the  same 
as  those  of  the  Laurentian  mountain  belt  of  Canada  ;  but 
no  Huronian  rocks  appear  on  or  around  them  ;  unless  the 
Green  mountains  of  Vermont  are  Huronian. 

No  one  doubts  that  the  Adirondack  rocks  when  they  sink 
at  Lake  George  rise  again  a  hundred  miles  further  south 
as  the  Highland  rocks  of  the  Hudson  river  above  and  below 
West  Point.  The  Hudson  Highlands  range  northeast  a 
few  miles  and  then  sink  out  of  sight  beneath  sedimentary 
formations.  But  in  the  other  direction,  southwest,  they 
range  away  across  New  Jersey  in  an  unbroken  belt  of 
mountain  ridges  called  the  Highlands  of  New  Jersey  ; 
cross  the  Delaware  river  into  Pennsylvania  between  Durham 
and  Easton  ;  cross  the  Schuylkill  river  above  and  below 
Reading  and  then  sink  underground. 

In  Pennsylvania  the  New  Jersey  Highlands  are  called 
the  Durham  and  Reading  hills ;  or  the  Lehigh  hills ;  or 
the  South  mountains  of  Northampton  and  Lehigh  counties; 
or  the  Highlands  of  Pennsylvania.  This  last  name  is  the 


62  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

most  convenient.  There  seems  no  probable  objection  to  be 
urged  against  recognizing  in  the  rocks  of  the  Highlands  of 
New  York,  New  Jersey  and  Pennsylvania,  the  rocks  of  the 
Adirondack  region  and  of  the  Laurentian  mountains  of 
Canada.  Therefore  the  term  Laurentian  gneiss  has  been 
freely  used  in  the  Reports  of  Progress  of  the  Survey  to 
signify  the  rocks  of  the  Pennsylvania  Highlands. 

But  it  is  quite  otherwise  with  the  Huronian  rocks  of 
Canada.  These  are  nowhere  recognized  along  the  High- 
land belt  from  the  Hudson  to  the  Schuylkill. 

We  will  see  hereafter  whether  they  appear  in  other  parts 
of  Pennsylvania,  in  the  South  mountains  of  Cumberland 
and  York,  Favette  and  Adams  counties. 


THE   ARCHAEAN    HIGHLAND    BELT.  63 


CHAPTER  VIII. 

The  Archcean  Highland  belt  of  Pennsylvania  and  New 
Jersey. 

In  New  Jersey  the  highlands  of  older  or  archsean  gneisses 
have  been  surveyed  with  instruments,  and  mapped  in  con- 
tour lines,  to  bring  to  view  all  the  features  of  the  surface. 
Some  important  facts  of  geology  have  been  thus  revealed. 
These  are  given  in  Prof.  Cook's  annual  report  of  1884, 
pages  61  to  68,  in  a  clear  and  careful  manner;  and  they  are 
of  equal  value  for  understanding  the  geology  of  the  same 
Archsean  Highland  belt  in  eastern  Pennsylvania.  They 
may  be  briefly  stated  thus  : 

1.  The  Highlands  of  New  Jersey  is  a  belt  of   country 
made  up  of  parallel  mountains  crossing  the  state  in  a  N.  E. 
and  S.  W.  direction,  with  heights  varying  between  1,000 
and  2,000  feet  above  tide. 

2.  Each  mountain  is  composed  of  a  series   of  smaller 
oblique  crest-ridges;  and  the  stratification  does  not  follow 
the  general  course  of  the  mountain  as  a  whole,  but  of  these 
oblique  crest-ridges.     Thus,  the  strike  of  the  beds  and  of 
the  crest-ridges  of  the  Ramapo  mountain  is  not  N.  38°  E. 
which  is  the  course  of  the  southeast  foot  of   the  mountain, 
but  N,  20°  E. 

3.  The  same  strike  is  not  maintained  across  the  state; 
for  near  the  New  York  line  it  is  more  N.  E.  and  S.  W.;  in 
the  middle  district  more  nearly  N.  N.  E.  and  S.  S.  W.;  and 
towards  Pennsylvania  more  N.  E.  and  S.  W.  again. 

4.  Therefore,  while  the  mountains  have  been  elevated  as 
a  parallel  series  of   large    arches,  they  have  been  subse- 
quently pressed  into  a    much  more    numerous    series  of 
smaller   rock-folds   by    a  side  pressure  which   has    acted 
obliquely. 


64  GEOLOGICAL    SURVEY    OF   PENNSYLVANIA. 

5.  The  folds  are  manifested  in  some  places  by  opposite 
southeast  and  northwest  dips;  rarely  less  than  45°,  in  most 
cases  exceeding  60°,  and  often  vertical.     Dips  towards  the 
northwest  are  not  uncommon;  but  nevertheless,  the  prevail- 
ing dip  is  toward  the  southeast;  therefore,  it  is  to  be  sup- 
posed that  a  large  number  of  the  steeper  southeast  dips 
are  exhibited  by  strata  which  have  been  pushed  northwest- 
ward beyond  the  vertical  so  as  to  lie  now  with  their  under- 
sides uppermost. 

6.  As  this  structure  characterises  the  belt  of  the  high- 
lands of  northern  New  Jersey  as  a  whole,  it  seems  impos- 
sible to  doubt  that  the  azoic  gneiss  formations  are  made 
up  of  regular  beds  of  sediment,  deposited  one  over  the  other 
in  some  ancient  sea,  and   afterwards   crystallized.      It  is 
hard  to  imagine  them  in  any  sense  volcanic  rocks.     For 
all  we  know  of  volcanic  rocks  leads  us  to  believe  that  irreg- 
ularity is  their  chief  feature.     Even  when,  like  the  lava 
beds  of  the  far  west,  they  spread  abroad  over  thousands  of 
square  miles,  they  construct  nothing  resembling  the  geology 
of  these  highlands. 

7.  But  the  regular  crest-ridge  structure  of  the  highlands 
is  not  shown  in  all  parts  of  the  map,  nor  is^the  appearance 
of  stratification  universal.     Dykes  and  veins  of  unstratified 
rock  are  common  in  all  parts  of  the  highlands.     There  are 
also  masses  of  syenite  or  hornblendic  granite  of  great  size, 
which  also  may  or  may  not  be  of  the  nature  of  the  lava 
coming  up  through  fissures.     One  such  belt  is  two  miles 
wide;  another  has  a  diameter  of   three  miles,  the  only  sign 
of  bedding  noticeable  being  the  parallelism  of  its  minerals 
in  some  specimens,  and  the  rock  being  an  almost  exclusive 
mixture  of  white  feldspar  and  glassy  quartz.     Wherever 
the  map  does  not  show  the  regular   oblique    crest-ridge 
structure  (that  is,  where  the  mountain  tops  are  shaped  by 
erosion  in  various  directions)  there  such  unstratified  masses 
may  be  justly  viewed  as  breaking  the  stratified  system. 

8.  No  contacts  of  the  stratified  and  unstratified  syenite 
or  granite  have  yet  been  noticed,  and,  therefore,  their  rela- 
tions to  each  other  are  a  matter  of  conjecture.     The  un- 
stratified masses  are  of  irregular  shape  and  seem  to  have 


THE   ARCHJ3AN   HIGHLAND   BELT.  65 

nothing  to  do  with  the  northeast  and  southwest  belting  of 
the  stratified  gneisses. 

9.  The  stratified  rocks  of  the  highlands  cannot  as  yet  be 
grouped  in  any  definite  order  of  superposition;   and  the 
same  varieties  of  kind  are  to  be  found  in  all  parallel  ranges 
or  belts.      A  representative  collection  of   rock  specimens 
from  one  belt  might  pass  for  that  from  the  next,  or  any 
other;  and  collections  made  along  many  lines   across  the 
region  resemble  each  other.     The  varieties  of  rock  in  any 
given  area  are  endless;  but  on  looking  over  the  entire  collec- 
tion from  all  parts  of  the  highlands,  two  principal  varieties 
are  recognized  as  predominating. 

10.  One  of  these,  a  light-colored  or  gray  variety,  is  com- 
posed  chiefly   of    white  or  pinkish-white  potash -feldspar 
(orthoclase)  and  glassy  quartz,  but  containing  usually  small 
brown-black  scales  of  mica.     Thisfeldspathic  gneiss  often 
contains  magnetic  iron,  hornblende,  phosphate  of  lirrie  and 
sulphide  of  iron,  and  perhaps  lime-soda  feldspar. 

11.  The  other,  a  greenish-black  variety,  is  made  up  chiefly 
of  hornblende,  with  dark  mica;  but  when  the  mica  becomes 
more  abundant  than  the  hornblende  the  rock  turns  into  a 
dark  mica-schist  or    micaceous  gneiss.      The   feldspar  is 
white   and   sometimes   triclinic.      Some  quartz  is  usually 
present. 

12.  Chemical  analyses  show  that  the  feldspathic  gneiss 
is  largely  siliceous,  with  a  comparatively  small  percentage 
of   alumina,  scarcely  any  iron  oxide,  still  less   lime  and 
magnesia,  and  no  excess  of  potash  and  soda;  and  that  the 
Jiornblendic  gneiss  is  deficient  in  silica,  potash  and  soda, 
but  has  the  more  iron,  lime  and  magnesia.     But  recent  de- 
posits show  the  same  elements  in  similarly  varied  mixtures. 
The  azoic  rocks  of  the  highlands  therefore  may  have  had 
a  sedimentary  origin,  although  they  are  so  highly  crystal- 
line; and  if  so,  their  original  stratification  ought  to  be  more 
or  less  recognizable  in  spite  of  changes  wrought  by  heat 
and  pressure. 


66  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

The  Pennsylvania  Highlands. 

Such  is  the  lesson  taught  by  the  survey  of  the  New 
Jersey  highlands;  and  it  is  repeated  by  the  survey  of  the 
same  belt  in%  its  extension  in  Pennsylvania.  All  that  has 
been  said  by  Prof.  Cook  of  the  New  Jersey  azoic  rocks,  is 
confirmed  by  Mr.  D'Invilliers  in  his  report  on  the  azoic 
rocks  of  Berks  county,  described  in  his  Report  of  Progress 
D3,  Vol.  IT,  1883,  pages  49  to  57. 

These  Pennsylvania  highlands  also  have  been  instru- 
mentally  surveyed  and  mapped  in  contour  curves  on  a  large 
scale  (1,600  feet  to  one  inch)  and  published  (on  16  sheets), 
in  an  atlas  to  accompany  Reports  D2,  D3 ;  with  a  geologi- 
cally-colored index  map  (on  one  sheet),  on  a  reduced  scale 
(2  miles  to  an  inch)  showing : — the  ridges  of  gneiss,  both 
parallel  and  irregular  ; — the  patches  of  sedimentary  sand- 
stone which  once  spread  in  a  continuous  sheet  over  the 
whole  of  them  ; — the  limestone  valleys  north  and  south  of 
them ; — and  the  isolated  limestone  vales  between  them, 
proving  that  the  limestone  formation  also  once  spread  con- 
tinuously over  the  whole  region.  Of  these  facts  more  will 
be  said  hereafter  in  narrating  the  history  of  the  sedimentary 
formations.  At  present  we  are  only  concerned  with  the 
Azoic  mountain  ridges  themselves,  and  the  nature  of  the 
crystalline  rocks  of  which  they  are  composed,  concerning 
which  the  following  statements  may  be  confidently  made  : 

1.  The  Pennsylvania  highlands  make  an  Azoic  belt,  of 
irregular  width,  in  a  W.  S.  W.  direction  from  the  Dela- 
ware to  the  Schuylkill,  south  of  the  Lehigh  river.     But  iso- 
lated, short,  small  ridges  rise  through  the  overlying  sand- 
stone and  limestone  strata  north  of  the  Lehigh  river,  show- 
ing that  the  Azoic  floor  extends  underground  under  middle 
and  northern  Pennsylvania,  as  it  does  under  New  York. 

2.  The  sheet  maps  plainly  exhibit  an  oblique  arrange- 
ment of  N.  E.  and  S.  W.  bearing  subordinate  ridges ;   and 
the  limestone  vales  of  the  belt  conform  rather  to  this  direc- 
tion than  to  that  of  the  belt  as  a  whole.     This  oblique  ten- 
dency, however,  seems  to  belong  to  the  more  ancient  fold- 
ing of  the  Azoic  rocks  rather  than  to  the  later  movements 


THE   ARCH.EATST   HIGHLAND   BELT.  67 

which  folded  the  overlying  sedimentary  strata.  This  is  just 
contrary  to  what  would  be  expected  by  a  classical  geologist. 
Nor  has  it  all  the  force  that  it  would  have  were  the  appar- 
ent stratification  of  the  gneiss  not  brought  into  doubt  by 
the  abundance  of  cleavage  planes,  and  were  the  apparent 
stratification  of  the  gneiss  traceable  for  long  distances  in 
any  one  fixed  direction.  But  the  very  reverse  of  this  is 
true. 

3.  The  apparent  stratification  of  the  gneiss  rocks  varies  in 
dip  and  strike  incessantly,  as  shown  by  the  arrows  on  the 
map  sheets  and  by  the  detailed  description  of  outcrops  in 
the  report,  pages  57  to  98.     From  this  it  will  appear  that 
the  rocks  dip  to  all  points  of  the  compass,  and  commonly  at 
high  angles,  rolling  over  from  south  to  north  and  from  east 
to  west  sometimes  in  well-defined  arches,  which  often  end 
or  die  down  suddenly.     Some  of  these  arches  run  length- 
wise of  the  belt ;  others  are  oblique  to  it  and  pass  beneath 
the  overlying  sandstone.     Thus,  near  Maple  Grove  the  arch 
of  the  Gap  Hill  is  marked  by  a  N.  34°  W.  dip  (of  87°)  and 
a  S.  60°  E  dip  (of  60°),  but  at  its  east  end  are  dips  of  S.  51° 
E.  (52°),  S.  48°  E.  (45°)  and  N.  70°  W.  (47°),  and  here  the 
arch  lies  under  the  sandstone.     Some  distance  from  this  the 
gneiss  dips  S.  70°  E.  (50°),  and  further  on,  S.  75°  E.  (57°), 
and  S.  80°  E.  (80°).     Along  this  ridge  there  is  plainly  a  local 
general  strike  very  oblique  to  the  general  direction  of  the 
whole  Azoic  belt.*    On  the  other  hand,  groups  of  expos- 
ures show  a  general  strike  east  by  north,  or  E.  N.  E.,  coin- 
ciding with  the  belt. 

4.  On  account  of  this  excessive  irregularity  which  per- 
vades the  whole  Azoic  belt  it  has  been  found  impossible  to 
classify  its  rocks  into  a  series  of  formations,  or  even  to 
show  with  any  satisfaction  the  course  of  the  outcrops  on  the 
map.     All  that  can  be  said  about  them  is  that  they  are  a 
badly  crumpled-up  mass  of  strata,  of  unknown  thickness, 
all  more  or  less  thoroughly  crystallized,  of  every  grade  of 
thick  and  thin-beddedness,  of  every  tint  of  gray  from  nearly 
white  to  nearly  black,  of  nearly  every  possible  mixture  of 
quartz,  feldspar,  hornblende,  magnetite  and  mica,  some  of 

*Report  D3,  Vol.  2,  p.  63. 


68  GEOLOGICAL   SURVEY    OF   PENNSYLVANIA. 

them  being  a  syenite,  some  a  granite,  some  a  granulite, 
some  a  hornblende-schist,  some  a  mica-schist,  some  a  mag- 
netic iron  ore  ;  and  all  these  kinds  passing  into  one  another, 
and  overlying  one  another,  as  if  the  original  sediments  (if 
sediments  they  were)  were  of  the  most  mixed  and  varied 
character,  yet  all  derived  from  essentially  one  source  and 
belonging  to  one  age,  an  age  moreover  not  overrich  in 
lime  and  magnesia,  if  we  may  judge  of  it  by  the  absence  of 
crystalline  limestone  beds  and  beds  of  talc  or  serpentine. 

5.  The  same  broad  distinction  between  a  prevalence  of 
dark  hornblendic  gneiss  (syenite}  carrying  beds  of  magnetic 
iron  ore  and  destitute  of  quartz,  and  a  prevalence  of  light- 
colored,    thick-bedded  granular   quartz-feldspar    gneiss 
(granulite\  destitute  of  mica,  is  noticeable  all  through  the 
l>elt  of  highlands. 

6.  The  Tiornblendic  rock  is  full  of  grains  of  magnetic 
oxide  of  iron;  and  a  good  deal  of  what  appears  on  first 
glance  to  be  hornblende  is  in  reality  magnetic  oxide  of 
iron.     The  quantity  of  iron  held  by  these  strata  must  be 
immense;  and,  therefore,  it  excites  no  wonder  to  see  many 
of  the  beds  rich  enough  in  iron  to  be  mined  as  beds  of  mag- 
netic   iron  ore.      Where  all  this   disseminated  iron  came 
from  is  a  mystery;  but  is  no  greater  mystery  than  where 
the    grains  of  quartz  sand  came  from  which  make  up  so 
large  a  part  of  the  granulite  variety.     Both  these  constitu- 
ent elements  of  azoic  strata  furnish  very  strong  evidence  in 
favor  of  their  sedimentary  origin.     But  if  this  be  granted  it 
still  remains  an  unanswered  question  where  were  the  more 
ancient  land  areas  from  which  these  quartz  and  iron  sands 
were  washed  down  into  the  azoic  sea  ;  and  what  kind  of 
country  could  that  have  been  to  furnish  such  stupendous 
quantities  of  iron  ? 

7.  The  granulite  strata   consist   of    grains  of   quartz, 
mixed  with  pinkish- white  feldspar,  and  also   with  some 
grains  of  magnetic  oxide  of  iron.     The  amount  of  quartz, 
however,  is  seldom  in  excess  of  the  feldspar;  that  is,  the 
quartz  usually  occurs  in  small  glassy  grains,  and  not  in 
chunks.     The  rock  is  therefore,  usually,  as  fine-grained  as 
it  is  massive,  and  in  this  respect  reminds  one  of  the  massive 


THE    ARCHAEAN    HIGHLAND    BELT.  69 

sandstone  strata  of  later  ages  and  undeniable  sedimentary 
origin.  The  feldspar  varies  in  color  between  dull  white 
and  flesh-pink,  greenish  and  bluish  tints  being  rarety  seen. 
The  feldspar  also  varies  in  its  relative  percentages  of 
potash,  lime  and  soda.  The  strata  in  which  the  potash 
feldspar  abounds  are  hard,  resist  the  weather  and  show 
their  stratification  plainly;  but  those  in  which  the  soda 
feldspar,  the  soda-lime  feldspar  and  the  lime  feldspar 
abound  are  softer,  weather  into  rounded  bowlders,  and  get 
so  covered  with  the  soil  which  they  make  in  mouldering  as 
to  conceal  their  stratification,  and  this  give  a  soft  and 
rounded  aspect  to  the  hill  slopes. 

8.  On  the  whole,  the  ridges  which  are  made  chiefly  by 
the  hornblende  gneiss  are  higher  and  rougher,  and  their 
crests  are  rocky;  but  the  ridges  which  are  made  chiefly  by 
fjranulite  rocks  have  rounded  summits.     The  ridges  on  the 
northern  side  of  the  belt,  where  the  iron  mines  are,  show 
the  hornblende  character  of  topography  more  plainly  than 
the  southern  side  of  the  belt;  and  this  geographical  fact 
may  have  an   important  geological  significance.     The  soils 
also  indicate  the  difference;  for  the  hornblende  districts  are 
covered  with  earth  stained  by  the  decomposition  of  the  iron 
element  to  a  deep  brownish  red;  whereas,  the  granulite 
districts  are  covered  with  light-colored,  sparkling,  sandy 
earth. 

9.  That  the  iron  ore  beds  are  original  parts  of  the  strati- 
fication and  not  ejections  from  below  is-  plainly  shown  in 
these  highlands  ;  for  they  lie  in  lens-shaped  plates  between 
the  gneiss  rocks;  fining  off  to  an  edge  all  round;  or  rather 
fading  away  into  gneiss  rocks  so  gradually  that  one  cannot 
say  where  the  bed  ceases  to  be  an  ore  and  becomes  an  un- 
profitable rock.*     It  seems  conclusive    logic  that  if  the 
magnetic  ore  beds  lie  thus  between  the  gneiss  rocks,  the 
whole  azoic  mass  must  be  a  sedimentary  formation. 

10.  The  absence  of  any  noteworthy  mica  schist  forma- 

*Report  D3,  Vol.  II,  page  239.  Along  the  southern  edge  of  the  azoic  belt 
some  limestone  has  been  deposited  with  the  magnetic  ore ;  and  there  is  a. 
hand  specimen  in  the  Pennsylvania  collection,  which  shows  three  parallel 
layers  of  ore  averaging  an  inch  in  thickness,  separated  by  two  layers  ot" 
Hmestone  each  three  or  four  inches  in  thickness. 


70  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

mation,*  of  any  remarkable  crystalline  limestone  beds,f  and 
especially  of  any  magnesian  formation  (chlorite,  talc,  ser- 
pentine,:}: &c.),  in  the  Pennsylvania  highlands  between  the 
Schuylkill  and  Delaware  rivers,  shut  in  as  they  are  on 
both  the  north  and  south  sides  by  sedimentary  fossiliferous 
sandstone  and  limestone  formation,  patches  of  which  lie 
upon  the  very  summits  or  are  preserved  between  the  ridges, 
makes  it  useless  for  us  to  seek  for  a  Huronian  formation 
here.  To  imagine  that  it  once  existed,  but  has  been  swept 
away,  or  that  it  lies  buried  many  thousands  of  feet  deep  to 
the  north  and  south  of  the  highland  belt,  is  a  mere  conjec- 
ture, worthless  because  unsupported  by  any  known  facts. 

The  Archaean  rocks  of  the  highlands  of  New  Jersey  pass 
across  the  Delaware  river  into  Northampton  county,  Pa. 
and  extend  in  parallel  ridges  through  southern  Lehigh  and 
Berks  as  far  as  the  Schuylkill  river  at  Reading,  where  they 
sink  (westward)  beneath  the  Great  Valley  limestone,  not  to 
rise  to  the  surface  again  (as  a  mountain  range)  short  of 
York  and  Adams  counties.  § 

The  South  mountains  of  York  and  Cumberland,  Adams 
and  Fayette  were  formerly  supposed  to  be  a  geological  con- 
tinuation (or  revival,  geographically,  going  southwest)  of 
the  highlands  of  New  Jersey  and  the  Easton- Reading,  or 
Durham  hills ;  but  it  is  nearly  certain  that  the  South 
mountains  are  for  the  most  part  composed  not  of  Archrean 
(Laurentian)  but  Cambrian  (Huronian?)  strata. 

*Both  muscovite  and  biotite  mica  has  been  found  in  fine  scales  and  in 
large  plates  in  several  places.  See  D3,  Vol.  II,  page  53. 

fThe  crystalline  limestone  bed  in  the  report  of  the  first  survey,  as  running 
through  Colebrookdale,  was  sought  for  carefully  but  not  found  by  the 
second  survey.  D3,  Vol.  II,  page  56. 

JGreenish  talcose  slates  appear  along  the  southern  edge  of  the  belt  at  one 
or  two  places  and  will  be  described  in  another  place. 

§A  narrow  outcrop  crosses  the  Schuylkill  below  Reading  and  runs  a  mile 
or  two  west.  A  lew  miles  further  west  they  appear  again  in  Mulbaugh  hill- 
But  with  these  exceptions  there  is  a  gap  of  about  sixty  miles  in  the  direct 
Highland-Blue  Ridge  range  which  may  be  said  to  extend  from  Massachu- 
setts to  Georgia.  But  in  northern  Chester,  south  of  the  direct  line,  they  oc- 
cupy the  surface  in  the  Welsh  mountain  region,  and  still  further  south 
there  is  a  Philadelphia-Baltimore  belt  of  them  to  be  described  further  on. 


THE    ARCHAEAN   HIGHLAND   BELT.  71 

Archxan  types  in  New  Jersey. 

The  Archaean  (Laurentian)  rocks  of  Pennsylvania  have 
been  studied  as  closely,  but  in  some  respects  under  less 
favorable  circumstances  than  those  of  New  Jersey,  where 
they  have  been  subjected  to  repeated  examinations  and  are 
exposed  in  a  bolder  manner  and  in  connection  with  mining 
operations  at  many  places.  The  New  JerSey  report  of  1889 
is  of  special  value. 

It  distinguishes  four  types  or  characteristic  masses  of 
highland  strata,  without  positively  affirming  what  their  re- 
spective ages  are,  how  they  underlie  or  overlie  each  other, 
or  what  their  mutual  geological  relationships  may  really  be, 
but  very  particularly  describing  their  geographical  ranges 
and  their  mineral  constituents.* 

I.  The  Mount  Hope  type  (FeldspatMc  gneiss  of  Smock; 
in  part  the  Hornblendic  gneiss  of  Britton)  is  a  nuartz-feld- 
spar-magnetite  rock,  varying  from  massive  to  coarse  and  to 
fine-grained  and  beautifully  foliated,  often  obscurely  foli- 
ated on  a  fresh  unweathered  surface  ;  the  quartz  generally 
in  shot-like  grains  pressed  into  the  cleavage  face  of  the 
feldspar,  which,  under  the  pocket  lens,  gives  a  character- 
istic unmistakable  spotted  (poicilitic)  appearance  to  a 
broken  specimen ;  the  feldspar  both  orthoclase  and  plag- 
ioclase  ;  the  magnetite  usually  in  rough,  irregular  little 
grains,  occasionally  in  octrohedral  crystals,  and  sometimes 
largely  replaced  by  hornblende  and  scattering  flakes  of 
black  mica  (biotite}.  These  massively-bedded  and  usually 
well-foliated  strata  have  numerous  interstratified  layers  of 
hornblende-feldspar  rock  without  quartz,  some  of  them  only 
a  few  inches  thick,  others  many  feet  thick,  and  usually 
quite  destitute  of  magnetite. — The  typical  Mount  Hope 
rocks  usually  occupy  the  highest  ground  or  summits  of  the 
ridges  flanked  by  the  Second  or  Oxford  type  of  rocks; 
which  would  make  them  older  than  or  underlying  the  Ox- 
ford ;  but  there  are  important  exceptions  to  this  general 

*New  Jersey  An.  Rt  1889,  part  2,  page  12,  Geological  Studies  of  the 
Archaean  Rocks,  by  Frank  L.  Nason.  See  Geol.  Rts.  of  Pa.,  by  Persifor 
Frazer,  Fred.  Prime,  C.  E.  Hall  and.E.  V.  d'lnvilliers,  C,  C2,  C3,  C4,  C5, 
D,  D2,  D3,  Vol.  1  and  2. 


72  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

statement  which  perhaps  weaken  somewhat  the  correctness 
of  that  conclusion. 

The  Mount  Hope  type  rocks  may  be  separated  into  three 
classes:  1,  Light-colored  quartz  and  feldspar  rock.  2,  The 
same,  darkened  with  magnetite.  3,  The  same,  darkened 
with  hornblende,  or  biotite,  or  both.  Texture  and  general 
appearance  the  same  in  all.  Dark  (non-eruptive  diorite- 
looking)  feldspar-hornblende  layers  are  often  interstratilied 
with  them,  and  beds  of  solid  iron  ore  occur  in  all  three. 

II.  The  Oxford  type  (Syenite  gneiss  of  Smock;  in  part 
Honiblendic  gneiss  of  Britton),  always  well  foliated  (even 
in  fresh  broke  specimens)  and  not  so  heavy-bedded  as  the 
Mount  Hope  type,  consists  of  feldspar  (both  kinds)  and 
hornblende,  with  grains  of  quartz  frequently  rounded  and 
imbedded  in  the  feldspar;  always  only  a  small  proportion 
of    magnetite    (sometimes    octohedral)  ;    the    hornblende 
usually  distributed  in   strings   so  as    to  give    the   rock  a 
striped  appearance;  and  the  longer  axes  of  feldspar  often 
oblique  to  foliation.     The  railroad  tunnel  at  Oxford  tunnel 
shows  all  the  various  phases  of  this  type;  but  no  contact 
with  the  other  type  can   be   seen;   the  change   however 
seems  abrupt  and  radical.     The  Oxford  rocks  are,  however, 
almost  everywhere  seen  on  the  flanks  of  those  ridges  the 
central  mass  of  which  is  of  the  Mount  Hope  type.     The 
Mount  Scott  range  which  reaches  the  Delaware  is  a  suffi- 
cient example  and  introduces  the  distinction  of  types  into 
Pennsylvania. 

III.  The  Franklin  type  (probably  the  Biotite  gneiss  of 
Smock  and  Britton);  foliation  less  distinct;  texture  more 
uneven ;  crystals  of  biotite,  &c.  at  angles  to  each  otlier ; 
eyes   of   quartz  and   feldspar  singly  or   mixed  frequent 
(augenstructuf);  rocks  rather  thin  bedded;  frequent  inter- 
strata  of  biotite  and  hornblende  schist;  essentially  a  quartz- 
orthoclase -biotite  rock  (plagioclase  rare);  quartz  and  feld- 
spar grains  usually  sharply  angular,  in  striking  contrast 
with  other  types. 

IV.  The  Montmlle  limestone  type;  not  certainly  known 
to  belong  to  the  Archaean;  possibly  of  later  age.     Southeast 
belt  (A);  bluish  gray,   rarely  white;  crystalline ;  holding 


THE  ARCHAEAN   HIGHLAND   BELT.  73 

great  quantities  of  serpentine,  more  or  less  chrysolite;  also 
diopside,  in  some  places  small  crystals  of  muscomte  mica; 
never  tourmaline,  no  zinc,  no  iron.  Northwest  belt  (B) 
sparkling  white;  holding  graphite,  tremolite,  tourmaline, 
pyrite,  great  quantities  of  zinc,  and  also  beds  of  iron. 


74  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 


CHAPTER    IX. 
The  ArcJicean  rocks  of  Pennsylvania. 

1.  In  the  Reading  and  Durham  Jiills. 

Prof.  Prime  and  Mr.  C.  E.  Hall  have  described  the  high- 
land rocks  in  Lehigh  and  Northampton  counties  in  the 
same  general  terms;*  but  there  is  mention  made  not  only 
of  hornblendic  and  feldspathic  gneisses,  but  occasionally  of 
mica-schists,  rocks  composed  of  white  mica  and  decom- 
posed white  feldspar. f  Mr.  Hall  says,  that  the  crystalline 
rocks  are  composed  chiefly  of  quartz  and  feldspar;  that  mag- 
netite is  disseminated  throughout  the  rock  in  all  parts  of 
the  region,  and  that  the  magnetic  iron  beds  are  distinctly 
interstratified;  that  in  some  places  the  rock  contains  small 
amounts  of  dark  mica  and  pyroxene  (hornblende)  and  that 
occasionally  particles  of  mica  and  magnetite  are  found  to- 
gether; but  that  many  rocks  are  wholly  of  quartz  and  feld- 
spar. One  vein  (?)  of  corundum  has  been  found.J 

The  Delaware  river  cuts  through  five  ridges  of  these 
rocks,  separated  by  valleys  filled  with  sedimentary  lime- 
stone. Some  of  these  ridges  seem  to  be  rock  arches  pressed 
•over  northwards.  In  the  third  ridge  at  least  800  and 
perhaps  1,200  feet  of  strata  show  themselves. § 

This  anticlinal  structure,  however,  cannot  be  made  out 
in  the  ridges  of  the  belt  as  a  whole.  Some  of  the  ridges 
seem  to  be  monoclinal  and  others  synclinal.  It  is  quite 
impossible  to  be  sure  of  the  correctness  of  any  kind  of 
structure  anywhere.  Nevertheless,  there  are  places  where 
plenty  of  opposing  dips  can  be  observed,  although  it  can 
seldom  be  decided  that  they  lie  on  two  sides  of  an  arch,  or 

*Reports  D,  D2,  D3,  Vol.  I. 

|D2,  page  7. 

$D3,  Vol.  I,  pages  254-255. 

§The  difference  being  due  to  the  possible  existence  of  a  roll. 


OLD   GNEISS   IN    CHESTER   COUNTY.  75 

on  two  sides  of  a  basin.     One  example  will  be  sufficient  to 
illustrate  the  difficulties. 

The  Hexerikopf  (  Witch  s  head)  is  the  highest  point  of 
land  southwest  of  Easton  where  two  of  the  azoic  ridges 
converge.  On  its  north  slope  gneiss  rocks  dip  to  the  S. 
E.  54°;  at  its  south  brow  29°;  on  the  south  slope  they  dip  to 
the  N.  W.  36°,  60°  and  50°.  There  is  certainly  a  basin  on  the 
south  slope,  even  if  there  be  an  overturned  arch  at  the 
crest;  if  there  be  no  such  arch  then  the  whole  mountain  is 
a  basin  with  at  least  1,200  and  possibly  2,000  feet  of  azoic 
strata  visible  on  each  of  its  sides.* 

#.  In  northern  Chester  county. 

The  Welsh  mountain  azoic  district  of  northern  Chester 
county  is  nowhere  more  than  500  feet  above  present  sea 
level;  is  surrounded  by  sedimentary  sandstone  and  lime- 
stone (although  the  northeastern  rim  is  concealed  by  still 
later  deposits);  and  was  once  covered  by  them,  as  is  shown 
by  the  patches  of  sandstone  left  upon  it.  It  does  not  lie 
in  the  W.  S.  W.  prolongation  of  the  highland  belt  of  Berks 
county,  but  to  the  south  of  it;  the  present  interval  between 
their  edges  being  ten  miles.  This  interval  represents  an 
ancient  valley,  of  great  but  unknown  depth,  now  filled  up 
with  Palaeozoic  white  sandstone  and  limestone,  covered  in 
turn  by  a  thick  mass  of  Mesozoic  brown  sandstone  and 
shale.  The  azoic  rocks  of  both  districts  undoubtedly  meet 
beneath  this  valley  and  form  its  floor,  covered  entirely  by 
the  white  sandstone  and  limestone  which  rise  to  the  pres- 
ent surface  on  both  sides  of  it;  the  sandstone  being  about 
100,  and  the  limestone  about  2,000  feet  thick,  and  perhaps 
covered  in  places  by  a  third  deposit  of  slate;  but  of  this 
we  know  nothing;  only,  it  is  certain  that  the  limestone  in 
the  valley  suffered  erosion  before  the  Trias  sand  and  shale 
was  deposited  upon  it  in  much  later  times.  The  thickness 
of  these  later  brown  sands  and  shales  is  also  unknown; 
but,  judging  by  the  dips  and  distances,  they  must  be  nearly 

*See  the  accompany  page  plate,  showing  both  alternative  constructions; 
also  the  description  of  the  locality  and  its  rocks  on  pages  75  and  251,  of 
Report  D3,  Vol.  1,  1883. 


76  *    GEOLOGICAL   SURVEY    OF   PENNSYLVANIA. 

4,000  feet  thick  along  their  northern  edge.  The  ancient 
buried  valley,  then,  must  be  about  as  deep  beneath  the 
present  mountain  surfaces  to  the  north  and  south  of  it  as 
the  valley  of  the  Rhone  between  the  two  enclosing  ranges 
of  the  Alps.  Originally  this  could  not  have  been  the  case; 
for  the  brown  sandstone  strata  all  dip  northward  at  the  rate 
of  at  least  500  feet  to  the  mile;  so  that  if  they  were  de- 
posited horizontally,  either  the  Highlands  were  5,000  feet 
higher  than  they  are  now,  or  the  Welsh  mountain  district 
has  been  elevated  4,000  feet. 

The  Welsh  mountain  azoic  rocks  are,  as  we  might 
suppose  from  their  underground  connection  with  the  High- 
lands, the  same  dark  hornblendic  and  light  gray  feldspathic 
gneisses  which  have  been  described  in  the  foregoing  pages. 
Being  more  easily  destroyed  by  the  weather  than  the 
white  sandstone  which  was  afterwards  deposited  upon  them, 
their  outcrops  lie  in  shallow  vales  between  ridges  of  white 
sandstone;*  but  this  is  owing  to  the  fact  that  the  softer 
white  feldspathic  gneisses,  interbedded  with  the  harder  dark 
hornblendic  gneisses,  make  up  the  greater  part  of  the  form- 
ation as  it  appears  at  the  present  surface.  By  far  the  most 
prevalent  variety, is  a  feldspar-quartz  rock  (granulite)  of  a 
grayish-white  color,  holding  only  a  subordinate  amount  of 
mica,  and  deposited  in  comparatively  massive  beds.  Some 
of  the  finer-grained  kinds  can  hardly  be  distinguished  from 
the  white  sandstone  afterwards  deposited  upon  the  azoic 
rocks. f  Micaceous  gneiss  strata,  however,  are  also  some- 
times seen;  but  nowhere  in  outcrops  of  considerable 
breadth ;  and  true  mica  slate  only  in  thin  interstratified 
layers. 

It  is  very  noteworthy,  that  in  this  Welsh  mountain  azoic 
h'eld,  as  in  the  Highland  belt,  the  hornblendic  rocks  prevail 
along  its  northern  portions,  and  the  feldspathic  rocks  along 
the  middle  and  southern  portions.:}:  No  reason  for  this 
can,  in  our  present  knowledge  of  the  azoic  formations,  be 
given.  Eor  even  if  it  be  true  that  two  grand  rock  waves  and 

*Dr.  Frazer's  Report  C4,  page  163. 
fPages  164-165. 
tCM,  p.  165. 


OLD  GNEISS  IN  CHESTER  COUNTY.  .  77 

several  smaller  ones  traverse  the  district  from  east  to  west, 
it  cannot  be  proved  that  the  hornblendic  gneisses  are  lower 
in  the  series  than  the  feldspathic  gneisses  ;  or,  that  they 
are  brought  up  only  by  the  northern  arch.  Such  a  suppo- 
sition is  merely  a  tempting  conjecture. 

Plumbago  beds  have  been  found  in  at  least  three  places 
in  the  district.  One  3  feet  thick  lies  between  gneiss  strata 
dipping  45°  to  the  S.  E.*  Another  is  a  gneissoid  stratum 
12  to  15  feet  thick  containing  about  4  per  cent,  of  dissem- 
minated  graphite,  which  is  shown  to  be  merely  an  element  in 
the  rock  by  the  fact  that  the  stratum  includes  horses  of 
whitish  rock  without  graphite,  f  An  outcrop,  traceable  for 
a  long  distance,  is  that  of  a  curious  conglomerate  (so- called) 
containing  graphite  ;  but,  although  the  rock  looks  like  a 
conglomerate,  it  is  more  likely  to  be  a  decomposed  por- 
phyritic  crystalline  rock  if  judged  by  the  fresh  character 
of  its  feldspar,  the  unworn-  angles  of  its  quartz  crystals, 
and  the  even  distribution  of  the  "graphite  through  it.J 

Although  exhibitions  of  plumbago  in  these  azoic  rocks 
suggest  a  relationship  to  the  Canadian  azoic  rocks,  they  can 
have  no  time  value  for  settling  the  order  of  the  series,  even 
were  the  relative  age  of  the  Canadian  plumbago  beds  estab- 
lished ;  for  the  origin  of  the  graphite  is  wholly  unknown. 
For,  while  it  is  looked  upon  by  some  as  a  proof  of  fusion, 
like  the  graphite  in  cast  iron,  others  rely  on  it  as  a  confir- 
mation of  the  sedimentary  character  of  the  rocks  which 
hold  it,  as  if  it  represented  the  consolidated  and  recrystal- 
lized  remains  of  living  creatures,  the  first  and  lowest  kinds 
of  plants  or  animals.  And,  in  fact,  graphite  is  found  both 
in  lava  and  in  limestone. 

Porphyries  occur  with  the  hornblende  syenite  ;  and  these 
consist  of  a  mixture  of  large  crystals  of  potash  feldspar 
and  white  (sometimes  amethyst-colored)  quartz,  sometimes 
enough  mica  being  present  to  make  the  rock  a  coarse  por- 
phyritic  granite.  The  syenite  layers  are  a  dark  compound 
of  hornblende  and  white  feldspar,  and  weather  into  round 
boulders  and  clay,  and  show  iron  stains. § 

*C4,  p.  222.  fc4,  p.  251.  JC4,  p.  254. 

§Dr.  Frazer,  C4,  p.  215.  Dr.  Genth's  analysis  of  such  syenites  exhibits 
labradorite  and  andesite  with  pyroxene. 


78  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

The  absence  of  limestone  and  serpentine  beds  from  the 
azoic  district  of  northern  Chester  is  as  noteworthy  as  their 
absence  from  the  Highlands  of  Berks,  Lehigh  and  North- 
ampton counties. 

The  Welsh  mountain  proper  is  the  westward  extension  of 
the  northern  part  of  the  district  into  Lancaster  county;  a 
prong  of  gneiss,  covered  partially  with  sedimentary  white 
sandstone,  sinking  beneath  the  great  limestone  plain  of 
Lancaster,  and  not  rising  again  to  the  surface,  although  the 
sandstone  reappears  on  the  Susquehanna  river,  above  Col- 
umbia, and  again  in  the  Pigeon  hills,  on  the  Adams  county 
line.  (Chiques  or  Hellam  quartzite.) 

A  southern  prong  of  gneiss,  covered  with  sandstone,  and 
known  as  the  Gap  hills  and  Mine  ridge,  extending  much 
further  through  Sadsbury  and  Bart  townships,  sinks  beneath 
the  limestone,  and  does  not  rise  again  to  the  present  sur- 
face. At  one  point  on  the  Susquehanna  river,  at  the  mouth 
of  Tocquan  creek,  in  the  center  of  a  flat  arch  of  great 
breadth,  the  gneisses  which  have  been  described  in  the 
Highlands  and  in  the  Welsh  mountain  region,*  should  make 
their  appearance ;  but  they  do  not — neither  the  horn- 
blendic  nor  feldspathic  gneisses — but  the  vast  arch  is  made 
up  of  micaceous  gneisses  and  mica  schists,  apparently 
many  thousands  of  feet  in  thickness,  as  will  appear  here- 
after in  the  course  of  this  history. 

West  of  the  Susquehanna  river,  in  Pennsylvania,  the 
highland  rocks  nowhere  reach  the  present  surface,  for  the 
rocks  of  the  South-Mountain-Blue-Ridge  range  belong  to  a 
different  system,  as  will  be  described  further  on.  We  will 
therefore  turn  back  here  and  describe  them  as  they  ap- 
pear along  the  Philadelphia  belt  in  southern  Bucks,  Mont- 
gomery, in  Delaware  and  in  southern  Chester  counties, 
where  we  will  find  them  supporting  the  white  sandstone 
and  limestone  sedimentary  formations,  but  also  in  contact 
with  another  great  azoic  system  of  an  entirely  different  char- 
acter and  of  as  yet  unsettled  age. 

*Prof.  Frazer's  report  on  Lancaster  county,  C3,  p.  71,  128.     See,  also,  the 
third  line  of  the  Susquehanna  river  section,  sheet  3,  in  the  Atlas  to  C3. 


OLD   GNEISS   OF   BUCK    RIDGE.  79 

3.  In  Bucks,  Montgomery  and  Delaware  counties. 

At  the  Delaware  river,  opposite  to  the  city  of  Trenton,  a 
low  range  of  old  azoic  gneiss  is  seen  rising  from  beneath  the 
mesozoic  brown  sand  and  shale  formation  and  running  in  a 
straight  course  west  southwestward  thirty  miles  to  the 
Schuylkill  river  above  Philadelphia.  For  the  first  few 
miles  it  is  more  or  less  concealed  by  the  earliest  Delaware 
river  gravels.  From  the  gorge  of  the  Neshaminy  to  the 
gorge  of  the  Pennypack,  it  makes  what  is  locally  known  as 
the  Buck  ridge,  with  a  constant  width  of  2^  miles.*  At 
Willow  Grove,  in  Montgomery  county,  it  splits — the 
northern  fork  soon  disappearing  beneath  the  edge  of  the 
mesozoic  country  to  make  its  underground  connections 
with  the  Welsh  mountain  region  of  northern  Chester — its 
southern  fork  keeping  on,  as  a  narrow  thread,  into  Dela- 
ware county,  where  it  spreads  out  into  three  separated 
areas,  the  northern  one  passing  on  into  southern  Chester  and 
the  southern  one  into  the  State  of  Delaware. 

Between  the  two  forks  commences  the  range  of  white  sand 
stone  and  overlying  limestone,  of  the  Chester  county  valley, 
which  runs  straight  W.  S.  W.  for  sixty  miles,  past  Con- 
shohocken,  Downingtown  and  Coatesville,  into  Lancaster 
county.  The  valley  is  evidently  a  long  and  narrow  basin, 
at  least  towards  its  eastern  end,  where  the  limestone  is  seen 
lying  in  a  spoon  of  sandstone,  and  the  sandstone  lies  in  the 
spoon-shaped  depression  which  splits  the  ridge  of  gneiss. 

There  can  be  no  mistaking  the  fact  that  here  the  Chiques 
sandstone  reposes  directly  upon  the  old  azoic  gneiss  floor 
of  Pennsylvania,  without  the  intervention  of  any  other 
azoic  rocks,  just  at  it  rests  upon  the  old  azoic  gneiss  of  the 
Reading  hills.  So  also,for  miles  along  the  North  Valley 
Hill  in  Chester  county,  this  "  North  Valley  Hill  sandstone  " 
or  quartzite  is  seen  lying  directly  upon  the  older  azoic  gneiss 
of  the  Welsh  Monntain  country 

But  it  is  equally  evident  that  the  age  of  the  older  gneiss 
and  the  age  of  the  sandstone  were  separated  by  some  great 
interval  of  time,  for  the  sandstone  lies  comparatively  flat 

*See  map  on  page  39  of  Report  06,  and  large  sheet  mapln  C6. 


80  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

upon  the  nearly  vertically  upturned  edges  of  the  gneiss. 
The  sandstone  basin  is  real ;  the  basin  of  gneiss  is  false — a 
mere  valley  worn  out  of  a  much  older  surface  of  uplifted, 
compressed  and  complicated  rocks.  How  many  ages  were 
required  for  working  down  the  ancient  range  of  gneiss  into 
hills  and  hollows  before  the  sand  of  the  sandstone  was 
drifted  into  the  water  around  the  gneiss  spurs  is  the  most 
important  question  to  be  asked  of  our  geology,  and  the 
most  difficult  to  be  fitted  with  a  proper  and  probable  answer. 
For  during  those  intermediate  ages  the  rain  had  been  al- 
ways falling,  and  the  rivers  running  to  the  seas,  and  the 
seas  adjusting  their  deposits.  But  where  were  the  lands 
overhung  with  clouds  and  traversed  by  streams?  And 
where  were  the  seashores  along  which  the  tides  were  rolling 
gravel  and  spreading  out  the  new  formations  of  sand  and 
mud  ?  And  where  shall  we  seek  for  the  rocks  which  rep- 
resent those  gravels,  sands  and  muds  ?  And  in  what  con- 
dition should  we  expect  to  find  them,  crystalline  or  uncrys- 
talline,  fossiliferous  or  non-fossiliferous  ? 

The  Buck,  ridge  gneiss  (always  called  syenite  in  Mr. 
Hall's  reports  C5  and  C6)  has  the  character  of  the  prevail- 
ing rocks  of  the  Highlands  and  Welsh  mountain  district. 
The  rocks  are  composed  chiefly  of  quartz,  feldspar  and 
hornblende.  The  beds  are  often  massive,  but  usually  have 
thin  bands  of  black  mica  or  of  hornblende.  They  are 
syenites,  gneissic  granites,  or  granite  gneisses.  A.  peculiar 
bluish  quartz  is  a  remarkable  feature  of  the  formation.* 
Small  particles  of  magnetite  are  in  some  places  scattered 
through  the  rock  ;  but  nowhere  in  sufficient  abundance  to 
make  a  magnetite  iron  ore  bed.  Graphite  occurs  ;  and  in 
one  place  enough  of  it  in  the  rock  to  warrant  an  attempt  at 
mining,  which  however  was  abandoned. f  Crystalline 
limestone  occurs  near  Rockville,  at  Van  Artsdalen  quarry, 
so  well-known  to  mineralogists.:}:  A  gray  and  red  granite 
appears  between  Somerton  and  Feasterville. 

*Report  C6,  page  4. 

fThe  old  mine  on  A.  Johnson's  farm,  near  Feasterville,  Bucks  county. 
See  06,  page  57. 

tC6,  page  47.— NOTE.  After  his  long  survey  of  the  Philadelphia  belt  Mr. 
Hall  made  a  careful  re-survey  of  the  Highlands.  See  D2. 


OLD   GNEISS   OF   BUCK    RIDGE.  81 

Now  the  rock  which  lies  upon  it  is  usually  a  fine-grained, 
thinly-laminated,  whitish  sandstone,  changed  by  infiltra- 
tion of  silica  into  a  quartzite,  and  full  of  small  scales  of 
light  -colored  mica  ;  but  some  of  the  beds  are  occasionally 
coarse  enough  to  be  called  a  fine  conglomerate;  and  east  of 
Willow  grove  there  are  massive  beds  of  conglomerate  made 
up  of  rolled  pieces  of  the  Buck  ridge  syenite  gneiss  and  the 
blue  quartz,  overlaid  by  finer  sandstone  beds  and  beds  of 
sandy  slate.*  This  shows  that  the  old  azoic  (syenite)  land 
was  not  very  far  off,  and  was  bare  of  any  newer  azoic  form- 
ations, mica-schists,  micaceous  gneiss,  &c.;  for  not  a  frag- 
ment of  any  such  rocks  can  be  found  in  the  sandy  conglo- 
merate, f 

Furthermore,  in  places  where  the  sandstone  was  not  de- 
posited, and  where  the  limestone  strata  therefore  rest 
directly  upon  the  old  azoic  gneiss  (as  at  the  furnace 
quarries  at  West  Conshohocken  on  the  Schuylkill)  the 
limestone  beds  contain  similar  fragments  of  syenite  which 
shows  the  neighborhood  of  an  old  azoic  seashore.;}:  But 
how  far  the  land  extended  back  from  the  shore  (towards 
the  present  Atlantic  ocean),  or  how  high  into  the  air  it  rose, 
must  be  left  to  the  imagination,  unguided  except  by  a 
single  fact,  namely,  that  in  a  long  subsequent  time  in  the 
history  of  the  earth,  at  the  end  of  the  Palaeozoic  ages  and 
the  beginning  of  the  Mesozoic  ages,  the  azoic  syenite  land 
was  out  of  water  just  as  it  was  out  of  water  at  the  begin- 
ning of  the  Palaeozoic  ages  when  the  white  sand  and  lime- 
stone were  deposited.  For,  at  the  southern  edge  of  the  Mes- 
ozoic brown  sand  and  slate  country  in  Bucks  and  Mont- 
gomery counties  the  bottom  beds  not  only  lie  directly 
upon  the  azoic  range  of  Buck  ridge,  but  are  conglomerates 
largely  made  up  of  rolled  syenite  rock  fragments.  But 
whether  this  particular  belt  of  azoic  land  remained  exposed 
to  the  air  through  all  those  Palaeozoic  ages,  during  which 
40,000  feet  of  strata  of  all  sorts  were  deposited  to  the  north- 
west of  it,  is  a  question  to  be  discussed  more  in  detail  here- 

*Exposed  in  the  N.  E.  Penn.  R.  R.  cut  below  Willow  Grove.     C6,  page  45. 
fC6,  page  5. 
JC6,  page  36. 
6 


82  GEOLOGICAL   SURVEY   OF  PENNSYLVANIA. 

after.  But  surely  Buck  ridge  could  not  have  remained 
through  all  those  ages  exposed  to  aerial  destruction  unless 
it  had  been  at  the  outset  of  them  a  high  mountain  range. 
On  the  other  hand,  it  could  not  have  been  an  Alpine 
mountain  range  facing  the  Palaeozoic  sea  through  all  those 
ages  without  doing  more  than  dropping  a  little  gravel  into 
the  white  sand-beds  here  and  there,  into  the  lowest  beds  of 
Palaeozoic  limestone,  and  into  the  lowest  beds  of  the  Meso- 
zoic  sand  and  shale.  Were  it  the  mountainous  northwest 
edge  of  an  Atlantic  continent  it  must  have  been  somewhere 
or  other  broken  by  mighty  rivers  draining  such  a  con- 
tinent. Where  are  the  deposits  which  such  rivers  must  have 
made  in  all  that  lapse  of  ages?  We  will  see  in  due  time. 
But  surely  no  such  rivers  opened  their  mouths  in  Bucks  or 
Montgomery  counties;  for  the  sandstone  (which  is  indeed  a 
vast  delta  deposit,  extending  far  and  wide  in  the  United 
States,  as  we  shall  see  hereafter)  is  so  thin  in  eastern  Penn- 
sylvania that  it  can  stand  for  but  a  transitory  operation  at 
an  early  period  of  the  Palaeozoic  age  ;  being  immediately 
followed  by  the  great  oceanic  magnesian  limestone  forma- 
tion (at  least  2,000  feet  thick  in  the  azoic  regions,  but  more 
than  6000  feet  thick  in  middle  Pennsylvania)  representing 
a  totally  different  relationship  of  continental  and  oceanic 
circumstances. 

In  the  face  of  all  these  difficulties  we  might  assume  that 
the  Buck  ridge  azoic  district  was  a  long  narrow  island 
at  the  time  when  the  sandstone  was  deposited  around  it. 
But  if  so,  this  island  must  have  been  the  crest  of  a  moun- 
tain ridge  belonging  to  a  much  larger  extent  of  azoic  land 
which  had  sunk  and  become  submerged — at  least  50  miles 
broad — namely,  from  Trenton  up  the  river  Delaware  to  the 
gap  in  Chestnut  ridge  above  Easton;  for  over  the  whole  of 
this  breadth,  as  we  have  seen,  the  sandstone  and  limestone 
were  deposited.  And  it  looks  as  if  the  Buck  ridge  was 
the  only  azoic  island  at  that  time.  For  the  sandstone 
patches  on  the  Welsh  mountain  region  and  on  the  tops  of 
the  Berks  county  highlands  remain  in  evidence  that  these 
were  all  submerged.  Yet  this  seems  a  very  strange  fact  on 
noticing  that  the  Highland  summits  now  stand  1,000  feet 


OLD   GNEISS   OF   BUCK    RIDGE.  83 

above  tlie  present  sea  level,  and  Buck  ridge  only  about  400 
feet. 

We  should  be  obliged  then  to  suppose  one  of  three 
things,  either  that  Buck  ridge  has  sunk  additionally  since 
then;  or  that  the  Highlands  have  been  lifted  additionally 
since  then;  or  that  the  whole  azoic  underground  country  on 
which  they  both  stand  has  been  tilted  or  warped  to  produce 
the  difference  of  height. 

How  idle  are  all  such  conjectures  to  account  for  the  im- 
aginary fact  that  Buck  ridge  remained  an  island,  while  the 
higher  Highlands  were  beneath  the  sea  level,  when  the  only 
reason  for  supposing  it  an  island  is  furnished  by  syenite 
pebbles  in  the  sandstone  and  limestone  beds,  which- pebbles 
may  have  come  from  some  more  distant  azoic  land  no  longer 
to  be  seen  ? 

The  impotence  of  the  structural  geologist  to  encounter 
such  a  problem  with  success  becomes  more  and  more  ap- 
parent as  new  facts  present  themselves  to  be  adjusted  into 
place.  Since  those  remote  days  in  the  history  of  the 
planet  movements  of  many  kinds,  in  shape,  direction  and 
degree,  have  followed  each  other  at  shorter  or  longer  inter- 
vals, disguising  and  distorting  or  obliterating  each  others' 
traces;  while  the  perpetual  shifting  of  the  ocean  level  up 
and  down  in  all  ages,  often  produced 'by  foreign  catas- 
trophes, and  originating  even  on  the  opposite  side  of  the 
globe,  takes  from  us  the  only  index  and  measure  of  move- 
ment which  might  otherwise  be  at  our  command. 

We  know  not  when  the  excessive  plication  of  the  Buck 
ridge  gneisses  took  place,  whether  wholly  before  or  partly 
after  the  deposit  of  the  sandstone.  As  we  see  them  now, 
the  old  azoic  strata  stand  nearly  vertical.  But  it  looks  as  if 
two  principal  folds,  both  tightly  compressed,  run  along  the 
ridge,  one  producing  the  short  north  spur  at  Willow  Grove, 
the  other  following  the  narrow  belt  or  thread,  scarcely  a 
tnile  wide,  past  Chestnut  Hill  to  the  Schuylkill  just  below 
Conshohocken.  Whether  or  not  these -are  true  rock  arches 
is  much  more  than  doubtful.  But  if  they  be,  it  is  plain  to 
see  that  two  such  arches  in  a  breadth  of  two  miles,  if  re- 
stored by  ideal  projection  upward,  compels  us  to  believe 


84  GEOLOGICAL   SURVEY    OF   PENNSYLVANIA. 

that  Buck  ridge  was  once  a  mountain  10,000  feet  high  ; 
and  that  it  has  been  torn  and  worn  and  washed  away  down 
to  its  present  lowness.  There  is  no  difficulty  in  believing 
the  fact  of  its  great  height,  seeing  that  we  have  absolute 
proof  of  the  former  existence  of  mountains  20,000  feet  high 
in  middle  Pennsylvania,  where  now  in  the  place  of  them 
spread  smiling  limestone  valleys  not  800  feet  above  the 
level  of  the  sea.  The  difficulty  lies  in  finding  reasons  for 
deciding  whether  the  elevation  of  this  mountain  range  took 
place  before  or  after  the  deposit  of  the  sandstone  and  lime- 
stone of  the  Chester  county  valley.  For,  in  the  first  case, 
they  should  lie  more  horizontally  around  it  and  be  mixed 
with  itsdebris  to  a  vastly  greater  extent  than  they  are  :  and 
in  the  second  case,  they  must  have  covered  the  mountain, 
been  pushed  up  to  an  almost  vertical  posture,  been  eroded 
away  along  with  it,  and  their  eroded  outcrops  be  found 
now  on  both  sides  of  it  . 

To  test  the  question  let  us  look  at  their  present  attitude. 

On  the  north  side  of  the  Buck  ridge  proper  from  Trenton 
to  Willow  Grove,  and  on  the  north  side  of  the  short  north- 
ern prong  west  of  Willow  Grove,  the  sandstone  and  lime- 
stone cannot  be  found;  their  edges  lie  concealed  under- 
ground beneath  the  Mesozoic  brown  sands  and  shales. 
But  that  they  are  there  we  know  by  an  accident.  Among 
the  many  probable  faults  in  the  mesozoic,  one  is  so  great  in 
its  vertical  displacement — the  one  that  runs  from  the  Del- 
aware river  at  Centre  bridge  (15  miles  above  Trenton) 
south  westward  to  Forestville  near  Doylestown — as  to  bring 
the  ground-floor  of  sandstone  and  limestone  up  through  the 
mesozoic  to  the  present  surface.  This  happy  accident, 
taken  in  connection  with  their  appearance  again,  15  miles 
further  north,  alone:  the  south  flank  of  -the  Highlands  is 
quite  sufficient  to  justify  us  in  asserting  that  they  extend 
beneath  the  mesozoic  the  whole  distance  (30  miles)  between 
Buck  ridge  and  the  Highlands  ;  ofcourse  everywhere  lying 
upon  the  azoic  ground  floor ;  but  whether  flat  and  undis- 
turbed, or  compressed  into  folds,  or  simply  shifted  by 
faults,  we  cannot  tell. 

From  Willow  Grove  westward  to  the  Schuylkill,  along 


OLD   GNEISS   OF   BUCK    KIDGE.  85 

the  northern  side  of  the  south  prong  of  the  Buck  ridge, 
there  is  a  continuous  outcrop  of  sandstone  and  limestone 
(as  has  been  already  said)  turned  up  at  various  steep  angles 
from  60°  to  90°.*  These  are  the  north  dips  on  the  southern 
side  of  the  Chester  county  valley  basin  east  of  the  Schtiyl- 
kill ;  and  if  the  curves  of  the  basin  be  properly  drawn  they 
show  that  the  bottom  sandstone  beds  must  descend  to 
depths  of  many  thousand  feet  beneath  the  present  sur- 
face. But  if  the  argument  from  structure  be  good  for 
depth,  it  is  equally  good  for  height ;  and  we  are  compelled 
to  believe  that  these  beds  once  ascended  into  the  air  with 
these  steep  dips  to  an  unknown  elevation  above  the  present 
surface.  What  is  the  limit  of  this  their  uprise  into  the  air  ? 
What  is  to  prevent  us  from  believing  that  they  ascended 
upon  the  northern  flank  of  the  azoic  mountain  to  its  top, 
and  descended  its  southern  flank  to  an  equal  depth  beneath 
the  present  surface?  In  fact,  if  they  can  be  found  along 
the  southern  edge  of  the  azoic  ridge,  and  in  a  nearly  vertical 
posture  (descending  southward  beneath  the  present  surface) 
must  not  this  be  accepted  as  proof  that  they  arched  entirely 
over  the  azoic  mountain  when  it  was  at  its  highest  ?  No, 
not  quite  ;  for  it  will  still  remain  a  possibility  that  the  azoic 
arch  in  rising  and  pushing  up  a  still  higher  arch  of  over- 
lying sandstone  and  limestone,  broke  the  upper  arch  and 
left  two  edges  separately  projecting  (at  any  supposable 
height)  between  which  its  own  arch  (broken  or  unbroken) 
rose  still  higher  naked  in  the  sky.f 

But  the  main  point  is.  are  such  outcrops  of  sandstone 
and  limestone  to  be  found  on  the  south  side  of  the  azoic 
ridge  ?  And,  if  found,  can  we  be  sure  that  they  are  the 
very  sandstone  and  limestone  of  the  north  side  ?  Does  the 
sandstone  lie  upon  or  next  to  the  azoic,  and  the  limestone 
upon  or  outside  of  the  sandstone?  In  answering  these 
questions  the  following  statements  can  be  made  : 

*As  shown  in  Mr.  Hall's  cross  sections,  Figs.  18,  19,  20,  21  and  22,  on  page 
43  of  Report  C6. 

fin  discussing  the  Mesozoic  belt  of  Bucks  and  Montgomery  counties,  the 
elevation  of  the  Asoic  mountains  of  the  Philadelphia  belt  will  be  offered  as 
explanation  of  the  northward  dip  of  the  22,000  feet  of  Mesozoic  sediments. 
It  is  evident  that  the  Buck  Ridge  syenite  was  once  22,000  feet  or  more  be- 
neath its  present  position. 


86  GEOLOGICAL   SURVEY    OF   PENNSYLVANIA. 

1.  There  is  no  sandstone,  no  limestone  to  be  found  in  the 
Atlantic  coast  country  southeast  of  the  Buck  ridge  gneiss 
except  just  at  its  southern  edge.     The  country  between  it 
and  the  Delaware  river  is  occupied  by  a  great  series  of  azoic- 
rocks,  (which   will  come   under  discussion   in   due   time) 
among  which  not  a  single  stratum  of  sandstone  or  lime- 
stone can  be  found.     And  beyond  the  Delaware  river  the 
whole  breadth  of  New  Jersey  is  made  of  quite  recent  for- 
mations, lying  upon  a  mesozoic  floor.     If  Palaeozoic  sand- 
stones and  limestones  exist  beneath  the  mesozoic  floor  we 
must  be  content  to  remain  ignorant  of  the  fact  for  many 
years — at  least  until  the  legislature  of  New  Jersey  shall 
order  borings  profound  enough  to  reach  them  to  be  made, 
and  for  such  purety  scientific  knowledge  only. 

2.  An   outcrop   of  steep  sandstone  beds  actually   does 
run  along  the  south  side  of  Buck  ridge,  in  an  unbroken  line 
from  the  Trenton  city  bridge,  16  miles,  to  Huntingdon  valley 
(the  Pennypack  creek)  in  Montgomery  county.     For  the 
next  6  miles,  as  far  as  Abington  station  on  the  N.  Penn.  R. 
R.  it  makes  no  show.     Then   (at  Waverly  Heights)  it  re- 
appears and  runs  for  3  miles  to  near  Chestnut  Hill,  beyond 
which  it  is  no  more  seen.*     It  forms  a  low  ridge, , and  is 
known  as  the  Edge  Hill  sandstone  (eurUe,  quartzite,  ita- 
columite) ;  many  yards  in  thickness  ;f  standing  vertical; 
with  the  surface  edges  of  the  beds  often  pressed,  crushed 
or  "creeped"  over  at  an  angle  always  towards  the  south, 
(as  seen  in  fig.  17,  06,  page  41) ;  so  that   the  surface  ex- 
posure has  given  the  false  impression  that  the  formation 
dipped  northward  under  the  azoic  ridge  ;  but  it  is  the  same 
formation  as  the  sandstone  on  the  north  side  of  the  ridge. 

3.  An  outcrop  of  vertical  beds  of  limestone  also  runs  for 
some  distance  along  the  south  side  of  the  sandstone  east  of 
the  Pennypack,  making  the  little  valley  or  gentle  vale  of 
Huntingdon  creek.     West  of  the  Pennypack,  where  there 
appears  no  sandstone,  the  limestone  is    seen  running  on 
alongside  of  the  gneiss. 

*See  the  sheet  maps  of  06,  and  the  small  map,  Fig.  14,  on  page  39,  C6. 
fit  is  impossible  to  find  its  southern  edge   anywhere,  see  C6,  page  41, 
therefore  it  cannot  be  accurately  measured. 
jSee  fig.  25,  C6,  page  45. 


OLD   GNEISS    OF   BUCK    RIDGE.  87 

4.  The  west  end  of  the  sandstone  outcrop  at  the  Penny- 
pack  seems  (from  the  strike  of  the  beds)  to  be  sharpened 
to  a  point.  The  same  is  noticeable  at  the  east  end  of  the 
sandstone  outcrop  at  Waverly  Heights.  Some  would 
account  for  the  non-appearance  of  the  sandstone  in  the 
interval,  by  suggesting  that  the  sandstone  had  not  here 
been  deposited  on  the  gneiss,  which  would  account  for  the 
limestone  resting  against  the  gneiss.  But  an  irregular  line 
of  crush  faulting  would  afford  an  equally  good  explana- 
tion; and  such  a.  line  of  faulting  seems  called  for  by  the 
thinness  of  this  belt  of  limestone,  and  by  its  shortness  also; 
for  otherwise  why  should  not  the  limestone  run  as  far  as 
the  sandstone  does?  And,  as  the  limestone  is,  say,  2,000 
feet  thick  in  the  Chester  valley,  why  should  it  not  make 
a  much  greater  show  on  the  south  side  of  Buck  ridge? 
Other  considerations  (hereafter  to  be  presented)  add  testi- 
mony to  the  existence  of  a  great  fault. 

The  Buck  ridge  range  of  syenite  gneiss,  then,  has  been 
pushed  up  since  the  deposits  of  the  sandstone  and  lime- 
stone were  made  ;  and  through  them  as  overlying  deposits. 
The  syenite  gneiss  strata  were,  of  course,  under  water  when 
the  deposits  upon  them  were  made.  It  follows,  then,  that 
any  syenite  fragments  in  those  deposits  could  not  have 
come  down  from  the  Buck  ridge  strata,  but  must  have  been 
brought  from  some  syenite  land  at  that  time  out  of  water. 
Where,  we  know  not ;  certainly  not  the  Welsh  mountain 
district,  nor  the  "range  of  the  Highlands,  for  they  also  were 
under  water.  Perhaps  from  Delaware  county,  where  the 
syenite  areas  are  large  and  we  have  no  positive  testimony 
to  the  fact  of  their  being  then  submerged,  although  it  is 
hard  to  imagine  them  otherwise.  It  is  idle  to  look  far  afield 
elsewhere. 

The  Buck  ridge  range  of  syenite  gneiss,  however,  could 
hardly  have  been  pushed  up  thus  in  a  quiet  manner,  by 
simply  sharing  in  the  general  elevation  of  a  50  or  100  mile 
broad  region  of  which  it  was  ojae  of  the  mountain  ridges. 
For,  in  that  case,  the  sandstone  and  limestone  deposits  would 
have  been  lifted  also  in  a  quiet  manner  upon  it  with  their  hor- 
zontality  or  seabottom-slope-dips  preserved.  The  steepness 


88  GEOLOGICAL   SURVEY    OF   PENNSYLVANIA. 

of  their  present  dips  and  their  frequently  vertical  posture 
shows  that  the  Buck  ridge  was  not  lifted  but  squeezed  up; 
squeezing  also  the  sandstone  and  limestone  beds  in  its  own 
folds.  Therefore,  we  must  suppose  that  to  some  extent  its 
own  folds  correspond  to  their  folds;  or,  in  geological  terms, 
that  they  lie  to  that  extent  conformably  upon  the  gneiss 
strata. 

This,  however,  a  long  and  elaborate  study  of  the  whole 
ground  (represented  by  the  arrows,  &c.  on  Mr.  Hall's  sheet 
map)  shows  plainly  enough  that  they  do  not.  The  sandstone 
and  limestone  folds  sometimes  correspond  to  folds  in  the 
gneiss,  and  sometimes  they  do  riot;  and  many  of  the  strike 
and  dip  details  in  the  gneiss  are  evidently  inconsistent  with 
the  folds  in  the  sandstone  and  limestone. 

We  must  conclude,  therefore,  that  the  azoic  country  had 
been  subjected  to  movements  previous  to  the  age  of  the 
sandstone  deposits,  folded,  elevated  and  depressed, 
weather-beaten  and  eroded  by  streams,  and  sculptured  into 
a  region  of  hills  and  valleys,  which  had  to  be  resubmerged 
in  order  to  receive  the  sandstone  and  limestone  deposits 
upon  its  worn  and  irregular  surface. 

The  eastern  portion  of  the  Buck  ridge,  i.  e.  in  Bucks 
county,  shows  no  sign  of  an  anticlinal  arch  structure.  All 
the  dips  are  towards  the  south,  at  high  angles  (75°,  78°,  80°) 
all  across  from  the  sandstone  on  its  southern  edge  to  the 
border  of  overlapping  mesozoic  at  its  northen  edge.  On 
the  Neshaminy,  however,  the  belt  (two  miles  wide)  is  a 
regular  arch,  with  steep  south  dips  at  its  southern  edge,  a 
25°  south  dip  near  its  middle,  and  vertical  north  dips  at  its 
northern  edge.  Three  miles  further  west,  a  section  through 
Feasterville  shows  just  the  reverse,  63°  and  65°  N.  dips  on 
its  southern  edge  and  75°  S.  dips  on  its  northern  edge;  so 
that  one  would  think  that  Buck  ridge  was  here  an  azoic 
basin.  Four  miles  further  west,  along  the  Pennypack, 
where  the  belt  is  2£  miles  wide,  the  gneiss  is  vertical  or 
(overturned  ?)  80°  N.  at  its  .south  edge,  and  then  has  56°, 
70°  and  65°  S.  dips  for  1£  miles,  with  nothing  visible  along 
its  northern  edge  ;  and  this  is  within  half  a  mile  of  the  end 
of  the  sandstone  basin  ;  so  that  we  have  south  dips  in  the 


OLD   GNEISS    OF    RUCK    RIDGE.  89 

gneiss  in  direct  prolongation  of  the  north  dips  in  the  sand- 
stone. 

It  is  needless  to  illustrate  further  the  fact  that  the  sand- 
stone does  not  He  conformably  upon  the  gneiss,  in  the  sense 
of  the  earliest  history,  but  only  in  the  sense  of  the  later 
history.  And  here  it  is  necessary  to  point  out  a  geograph- 
ical fact  which  seems  to  remove  the  movements  of  this 
later  history  far  away  from  the  azoic  ages  and  bring  them 
down  to  the  very  end  of  Palreozoic  time,  to  the  close  of  the 
Carboniferous  age,  the  date  as  we  know  of  that  general 
movement  which  produced  all  the  folds  of  middle  and 
western  Pennsylvania  and  the  whole  belt  of  Appalachian 
country  from  New  York  State  to  Alabama.  This  geo- 
graphical fact  is  the  extraordinary  straightness  and 
peculiar  direction  of  the  south  edge  of  the  Buck  ridge  belt 
from  the  Delaware  river  at  Trenton  to  the  Delaware  county 
line,  as  shown  on  Mr.  Hall's  sheet  map. 

The  south  edge  of  the  Buck  ridge  (marked  by  the  vertical 
or  steep  south-dipping  sandstone  and  limestone,  and 
further  west  at  the  Schuylkill  by  serpentine  beds)  runs 
first  S.  80°  W.  2J  miles,  then  S.  62°  W.  6  miles,  then  S. 
79°  W.  18£  miles  (to  within  one  mile  of  the  Schuylkill),  then 
S.  61°,  W.  5  miles  (to  the  Delaware  county  line). 

Nothing  in  Pennsylvania  is  more  remarkable  than  this 
long  line  of  33  miles,  divided  into  four  parts,  two  of  which 
have  a  common  strike  of  61°,  62°,  and  the  other  two  a  com- 
mon strike  of  79°,  80°,  especially  when  we  consider  that  it 
represents  a  sudden  plunge  vertically  downward  and 
southward  (with  or  without  fault)  of  one  great  system  of 
rocks  beneath  another ;  for  one  of  these  strikes  is  almost 
exactly  parallel  with  that  of  the  great  plunge  of  the  whole 
Palaeozoic  system  of  formations  vertically  downward  and 
northward  into  the  Pottsville  coal  basin,  sixty  miles  dis- 
tant to  the  north,  along  a  line  (of  even  greater  length)  in  a 
direction  S.  62£°  W. 

The  significance  of  this  line  is  intensified  by  another, 
which  is  undoubtedly  in  some  way  connected  with  it,  viz : 
The  long  straight  line  of  the  vertically-plunging  limestone 
(marble)  beds  at  the  south  edge  of  the  Chester  county 


90  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

valley,  the  strike  of  which  is  S.  74°  W.  for  45  miles  west  of 
the  Schuylkill  river. 

Generalizations  become  more  dangerous  as  they  become 
larger  ;  but  it  is  impossible  to  shut  the  eyes  to  the  fact  of  a 
grand  parallelism  of  the  anticlinal  and  synclinal  folds 
throughout  Eastern  Pennsylvania,  produced  by  a  hori- 
zontal movement  from  the  southeast ;  or  to  the  fact  that  the 
system  of  parallel  folds  as  a  whole  is  itself  parallel  to  the 
special  uplift  of  the  azoic  belt  of  Buck  ridge  which  we  have 
been  describing  in  the  detailed  manner  which  its  import- 
ance justified. 

The  historical  azoic  question  raised  by  all  this  parallel- 
ism is  this : — Were  the  Palaeozoic  sediments  shoved  north- 
westward on  the  Azoic  floor,  adjusting  their  gigantic  pli- 
cations upon  it  without  regard  to  its  own  previously  pli- 
cated condition ;  — or,  did  this  azoic  floor  consist  of  a 
system  of  parallel  mountain  ridges  which  decided  the  par- 
allel direction  of  and  located  and  increased  the  Palaeozoic 
folds  ; — or.  was  the  real  folding  accomplished  in  the  azoic 
floor  itself,  the  Palaeozoic  formations  merely  sharing  in 
the  -movement ; — or,  was  the  whole  movement  a  complica- 
tion of  additional  azoic  crumplings  below,  with  new  pal- 
CBZOIC  foldings  above  ?  These  alternative  hypotheses  must 
be  discussed  more  fully  when  we  come  to  the  history  of  the 
palaeozoic  ages  ;  but  it  was  necessary  to  allude  to  them  in 
advance  in  drawing  attention  to  the  remarkable  line  of 
the  Edge  Hill  or  south  border  of  the  Buck  ridge  azoic 
belt,  and  especially  the  most  remarkable  part  of  it,  viz: 
the  16i-mile  straight  S.  80°  W.  line,  against  which  abuts 
diagonally  the  Philadelphia  gneisses. 


The  Buck  ridge  old  azoic  (syenite)  belt  crosses  the  Wis- 
sahickon  at  the  complicated  bend  of  the  creek  a  mile  west 
of  Chestnut  Hill;  not  as  a  ridge,  but  mouldered  away  to 
the  level  of  the  stream,  and  only  400  hundred  yards  wide. 
Thus  it  runs  on  a  mile  and  a  half  further  west  to  Barren 
Hill;  then  a  mile  and  a  half  farther  west  to  the  Schuylkill 
river  at  Spring  Mill,  where  it  is  just  one  mile  wide.  The 
river  after  crossing  the  limestone  valley  strikes  the  hill  belt 


OLD   GNEISS   ON  THE   SCHUYLKILL.  91 

of  syenite,  turns  east  and  flows  for  a  mile  at  its  foot  to 
Spring  Mill,  and  then  turning  at  a  right  angle  southward 
cuts  through  it  between  bluffs  of  nearly  vertical  syenite 
rocks  for  a  mile. 

Here  the  dark  hornblendic  rocks  are  pretty  plainly 
arched,  although  most  of  them  are  vertical,  or  dip  very 
steeply  northward  (as  the  sandstone  and  limestone  strata  do 
which  face  the  north  side  of  the  ridge);  but  obscure  south 
dips  are  seen  on  the  southern  side  of  the  belt,  where  the 
Philadelphia  system  abuts  against  it  along  a  line  of  fault, 
at  the  first  brook  above  Lafayette  station.  All  the  ex- 
posures from  here  down  the  river  past  Manuyunk  and  Phil- 
adelphia belong  to  the  Newer  Azoic  system  of  mica-schists 
and  micaceous  gneisses  to  be  described  in  the  next  chapter. 

In  Delaware  and  southern  Chester  counties  the  old 
syenite  azoic  areas  are  so  irregular  in  shape  that  they  can 
only  be  described  by  reference  to  the  geological  colored 
county  map.*  As  defined  by  Mr.  Hall  they  appear  as  on 
the  accompanying  sketch  map,  by  which  it  will  be  seen 
that  their  irregular  outlines  are  produced  by  the  partial 
removal  of  the  overlaying  Philadelphia  system  of  micaceous 
gneiss.  The  whole  district  is  a  low  rolling  hill  country  no- 
where more  than  about  500  feet  above  tide  level ;  and  the 
older  gneisses  being  more  easily  decomposed,  their  areas 
are  somewhat  sunk  beneath  the  general  surface,  and  sur- 
rounded by  the  indefinite,  gently  sloping  escarpments  of 
the  borders  of  the  micaceous  gneiss  areas.  Only  one 
syenite  area  has  a  well  determined  east  and  west  extension, 
between  Bryn  Mawr  and  West  Chester,  with  an  outlying 
area  further  on,  crossing  the  Brandy  wine.  Chester  creek 
makes  long  exposures  of  the  syenite,  which  appears  also 
on  the  Delaware  state  line  and  in  the  northernmost  county 
of  that  state 

4.  On  the  Schuylkill  River. 

Prof.  Rogers'  description  of  the  syenite  belt  where  it 
crosses  the  Schuylkill  river  is  given  on  page  76  of  his  geol- 
ogy of  Pennsylvania,  1858. 

*See  them  represented,  as  defined  by  Mr.  Hall,  in  a  plate  on  page  vii  of 
the  preface  to  Report  C4,  on  Chester  Co.,  1883. 


92  GEOLOGICAL   SURVEY    OF   PENNSYLVANIA. 

The  "harder  feldspathic  gneiss "  is  first  seen  (ascending 
the  Schuylkill)  north  of  the  soapstone  quarries,  dipping 
southward  70°  and  even  steeper;  and  then  northioard  45°  to 
55°,  making  a  sharp  anticlinal  arch,  up  through  the  broken 
center  line  of  which  has  flowed  a  strong  dyke  of  syenite 
gneiss.  Passing  the  blue  prophyroidal  gneiss  quarries  the 
strata  are  lying  nearly  flat  for  say  1,500  feet,  and  then  turn 
up  and  stand  nearly  vertical,  being  closely  compressed  into 
numerous  narrow  folds,  all  the  way  past  the  Wm.  Penn 
iron  furnaces,  nearly  to  Spring  Mill,  at  the  sharp  bend  of 
the  river,  where  the  valley  limestone  appears. 

He  describes  in  detail  (on  page  75)  the  character  of  the 
strata  from  the  dyke  northward;  commencing  at  a  small 
dyke,  100  feet  south  of  the  end  of  the  long  tangent  of  the 
Norristown  railroad,  which  follows  the  east  bank  of  the 
river.  His  description  may  be  divided  into  the  following 
parts : 

(a)  Dyke  of  syenite,  small,  composed  of  pinkish  feldspar 
and  quartz;  next  north  of  which  come 

(b)  Gneiss  rocks,  dipping  80°  >  N.  20°  W.,  composed  of 
feldspar,  quartz  and  hornblende  (with  some  mica),  coarsely 
crystalline,   evenly  bedded  with  parallel  lamination  (not 
minute    or    very    continuous)  dipping  80° >   N.   20°    W. 
(Some  beds  have  feldspar  in  excess  and  may  be  called  por- 
phyries.)   Similar  massive  gneiss  cut  by  the  Reading  rail- 
road on  opposite  river  bank.     Distance  along  railroad  160 
feet. 

(c)  Dyke  of  syenite  (about  100'  north  of  first  dyke). 
coarsely  crystallized  pinkish  and  white  feldspar,  with  a 
much  less  proportion  of  quartz,  and  a  considerable  amount 
of  large  specks  of  finely  granular  (imperfectly  crystallized) 
hornblende.  Dyke  10'  thick.  Contact  with  gneiss  makes 
a  plane  dipping  70°. 

(d)  Gneiss,  massively  bedded,  bluish  gray  (feldspar, 
quartz,  mica,  occasionally  some  hornblende),  many  beds 
prophyroidal,  feldspar  appearing  in  large  insulated 
blotches.  Granite  injections  in  gneiss  near  the  syenite 
dyke. 

Extensive  quarries.     Bold  nose  of  hill  at  bend  of  river. 


OLD   GNEISS   ON   THE   SCHUYLKILL.  93 

Dip  of  gneiss  for  the  first  250'  regular,  45°  to  50°  >  N. 
20°  W.  Then  rather  suddenly  flattens  to  a  small  angle. 

Dip  of  gneiss  at  900'  from  the  quarry,  gently  south. 

(e)  Interval  between  "  the  small  quarry"  and  the  south 
end  of  Wm.  Penn  furnace  No.  2,  387'.  Here 

(/)  Gneiss  massive,  dark-blue,  streaked  and  spotted  (with 
lens-shaped  white  blotches) ;  composed  of  feldspar  and 
dark  blue  mica,  in  alternate  slightly  wavy  laminae,  with 
lens-shaped  concretions  of  pinkish  feldspar.  In  some  of 
the  bands  these  lumps  are  so  abundant  as  to  make  the 
rock  porphyroid.  Other  bands  finely  laminated,  the  laminae 
being  in  delicate,  parallel,  slightly  wavy,  bluish  black  and 
pinkish  white  streaks,  according  to  the  relative  proportions 
of  the  dark  mica  and  pink  feldspar.  The  rock  contains 
some  quartz,  and  occasionally  some  hornblende.  Dip 
(under  furnace)  90°. 

(g)  Gneiss  (at  N.  end  of  furnace  No.  2)  feldspar  mica  ; 
some  of  it  minutely  banded  ;  no  feldspar  lumps. 

(k)  Trap  dyke  (266'  north  of  north  end  of  furnace  No.  2), 
very  hornblendic;  thickness,  8'. 

(i)  Gneiss  (421'  north  of  north  end  of  furnace  No.  2)  same 
as  (/);  some  beds  with  feldspar  lumps,  but  fewer  and 
smaller  than  in  (/);  all  more  minutely  and  evenly  lamin- 
ated than  (f)\  a  real  gneiss,  but  more  like  altered  clay- 
sandstone.  The  feldspar  weathers  mealy,  chalky. 

(/)  Dip  at  north  end  of  Old  furnace  No.  1.  60°  >. 

(k)  Gneiss  (100'  north  of  north  end  of  Old  furnace  No. 
1\  feldspar- mica;  exposed  for  170' ;  dip  at  south  end  of 
exposure,  80°  >. 

(I)  Gneiss  (?)  (330'  north  of  north  end  of  Old  furnace  No. 
1;  with  feldspar  lumps  and  specks  rounder  than  those 
of  (/);  finely  streaked;  looks  less  gneissic  and  more  sedi- 
mentary; strike  S.  70°  W.  (pointing  across  the  river  to  the 
ferry  house  opposite  Spring  Mill);  dip,  90°  >;  visible  thick- 
ness (in  exposure)  100' ;  ranges  along  the  base  of  the  hill 
slope  from  ferry  house  up  the  river  bank  to  Merion  furnace 
opposite  Conshohocken. 

The  rock  mass  (1)  conforms  to  the  vertical  gneiss  (&)  in 
strike  and  dip,  but  is  more  earthy  and  less  crystalline,  and, 


94  GEOLOGICAL   SURVEY    OF   PENNSYLVANIA. 

in  fact,  looks  so  different  that  Prof.  Rogers  feels  author- 
ized to  place  it  at  the  base  of  the  palaeozoic  system,  lying 
immediately  upon  the  gneisses  (&)  all  in  vertical  posture. 

The  difficulties  of  structure  are  great,  perhaps  insupera- 
ble. If  the  gneisses  be  closely  folded  and  the  folds  pressed 
together,  sp^as  to  make  one  dip,  and  there  be  no  clue  to  the 
character  of  the  last  or  northernmost  fold,  it  becomes  im- 
possible to  tell  whether  (I)  lies  upon  or  beneath  (&) ;  for,  if 
the  last  beds  of  (&)  are  rising  northwards,  then  (Z)  under- 
lies ;  if  falling,  then  (I)  overlies.  Mr.  Rogers  regards  the 
horizontal  middle  part  of  the  belt  as  a  basin,  but  it  may  be 
the  flattened  top  of  a  grand  arch  ;  in  which  case,  all  the 
vertical  gneisses  of  the  northern  side  of  the  belt  are  going 
down  together,  and  this  is  the  only  view  to  be  taken  of 
them  in  harmony  with  their  extension  eastward  and  their 
encircling  at  Willow  Grove  the  sandstone  and  the  limestone 
of  the  valley. 

Another  difficulty  arises  from  the  abundance  of  mica  in 
the  masses  (/)  (g)  (i)  and  (#)  and  especially  (d)  in  which 
hornblende  is  only  an  occasional  element.  In  fact,  only  di- 
vision (5)  of  the  whole  belt  is  distinctively  a  hornblende- 
syenite.  This  difficulty  will  be  felt  when  we  come  to  de- 
scribe the  Philadelphia  azoic  belt  lying  alongside  and 
south  of  this  Buck  ridge  belt  and  supposed  to  be  a  differ- 
ent system,  chiefly  if  not  exclusively  on  the  ground  of  its 
exceptionally  micaceous  character. 

As  for  the  two  "dykes"  of  syenite  (a)  and  (c)  containing 
little  or  no  hornblende,  they  may  be  integral  members  of 
the  series.  But  if  they  be  true  igneous  dykes  they  are 
merely  additional  examples  of  what  we  meet  with  in  the 
Highlands  and  Welsh  mountain  regions. 

The  trap  dyke  (7^),  very  hornblendic,  belongs  to  a  very  late 
time  of  disturbance  during  and  at  the  close  of  the  deposit  of 
the  Mesozoic  brown  sand  and  shale,  when  all  our  largest 
trap  dykes  were  ejected  from  the  interior  as  black  lavas, 
and  the  whole  region  of  middle  New  Jersey  and  southeast- 
ern and  southern  Pennsylvania,  in  fact  the  whole  wide 
belt  of  the  Atlantic  seaboard,  was  shattered  and  rifted  by 
continental  earthquakes  on  the  grandest  scale. 


ARE   THE   ARCHAEAN    ROCKS    SEDIMENTARY  ?  95 


CHAPTER  X. 
Are  t?te  Archcean  rocks  sedimentary? 

The  alternations  of  feldspar-gneiss  beds  with  hornblende- 
gneiss  beds  is  as  easily  explained  as  the  alternation  of  hard 
sand-rock  beds  and  shale  beds  among  the  sedimentary 
rocks;  or  as  the. alternation  of  limestone  and  magnesian- 
limestone  beds  in  great  limestone  formations. 

The  feldspars  are  combinations  of  the  silicate  of  aluminar 
with  silicates  of  lime,  soda  and  potash,-  and  a  little  magne- 
sia and  iron. 

The  hornblendes  are  combinations  of  the  silicates  of 
magnesia,  lime  and  iron,  with  more  or  less  silicate  of  al- 
umina, and  little  or  no  soda. 

The  chemical  analyses  of  both  the  feldspars  and  horn- 
blendes show  an  infinite  variety  of  these  combinations  ; 
which  means  an  infinitely  various  mixture  of  the  six  sili- 
cates of  alumina,  lime,  soda,  potash,  magnesia  and  iron ; 
as  might  be  expected  when  rivers  bring  down  sand  and  mud 
from  a  country  of  all  sorts  of  rock,  mixing  them  on  the 
way  in  all  possible  proportions,  and  laying  them  down  in 
beds  of  all  possible  thicknesses,  shapes  and  order  of  super- 
position. 

Where  the  pure  quartz  sand  was  in  great  excess,  the  rock 
became  a  quartzite.  Where  the  alumina  was  in  excess,  a 
massive  feldspar  rock  was  afterwards  produced.  Where 
the  quartz  was  simply  in  excess  of  the  alumina,  a  quartz- 
feldspar  syenite  gneiss  was  the  consequence.  Where  there 
was  a  considerable  charge  of  potash  and  a  small  charge  of 
iron,  the  deposit  became  a  quartz-feldspar  mica  granitic 
gneiss.  Where  magnesia  and  lime  were  abundant,  horn- 
blende crystals  were  formed,  if  the  deposit  did  not  origin- 
ally consist  of  rolled  hornblende  crystals,  obtained  from 
some  weathered  country  composed  largely  of  hornblendic 
rocks. 


96  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

In  a  word,  given  sediments  of  sand  and  mud,  composed 
of  coarse  and  fine  particles  of  quartz  and  feldspar,  some  of 
them  from  a  country  poor  in  magnesia,  others  from  a 
country  rich  in  magnesia,  there  must  result  alternations  of 
felsitic,  micaceous  and  hornblendic  gneisses,  in  beds  of 
every  thickness  and  thinness,  and  in  every  variety  of 
grouping. 

If,  in  the  upper  part  of  a  great  formation  feldspathic 
gneiss  beds  predominate,  while  in  its  lower  part  hornblendic 
gneiss  beds  predominate,  such  an  arrangement  ought  to 
indicate  that  the  drainage  of  the  country  which  supplied 
the  materials  was  at  first  more  magnesian  or  dolomitic,  and 
became  less  so  afterwards.  And  if  a  great  formation  with 
few  micaceous  beds  be  succeeded  by  a  great  formation  of 
mica  schists,  such  an  arrangement  Ought  to  indicate  another 
change  in  the  drainage  system,  viz.,  an  increase  in  the 
quantity  of  potash  with  iron  in  the  river  waters. 

Throughout  the  Cambrian,  Silurian,  Devonian  and  Car- 
boniferous ages  such  changes  in  the  drainage  system  of 
the  continent  which  furnish  the  numerous  palaeozoic  sedi- 
ments of  middle  and  western  Pennsylvania  certainly  took 
place,  or  else  we  should  not  now  have  that  remarkable  pile 
of  dissimiliar  formations,  arranged  in  no  assignable  logical 
order,  and  composed  of  an  infinite  variety  of  combinations 
of  coarse  and  fine  grains  of  quartz,  of  the  different  feld- 
spars, and  of  limestones  with  more  or  less  magnesia  and 
iron.  We  have  a  right,  therefore,  to  suppose  such  changes 
of  drainage  to  have  occurred  in  pre-Cambrian  time.  On 
this  supposition,  and  granting  the  possibility  of  the  partial 
or  complete  re-crystallization  of  sediments  with  a  total 
destruction  of  all  traces  of  organic  life  (if  such  existed),  it- 
becomes  an  easy  matter  to  explain  the  alternations  of 
syenitic,  hornblendic,  granitic,  micaceous  and  garnetiferous 
gneisses  and  schists,  with  clay  slates,  mica  slates,  talc 
slates  and  even  with  such  serpentine  beds  (hydrated  sili 
cates  of  magnesia  and  iron)  as  cannot  be  proved  to  have  had 
a  volcanic  origin.* 

*Even  Professor  Bonney  admits  this  distinction. 


THE   ARGUMENT   FROM   THE   MICROSCOPE.  97 

The  argument  from  the  microscope. 
There  is  a  new  school  of  geologists  who  trust  to  the 
microscope  for  deciding  whether  an  apparently  bedded 
mass  of  crystalline  rocks  were  originally  sedimentary 
strata,  or  whether  they  were  ancient  outbursts  or  out- 
flows or  overflows  of  molten  rock-glass  taking  on  the  ap- 
pearance of  stratification  in  the  course  of  their  lava-like 
movement.*  Such  geologists  take  a  totally  different  view  of 
the  order  of  the  old  gneiss  system  rocks,  and  reject  its  chro- 
nological subdivisions  into  Lower,  Middle  and  Upper  Laur- 
en tlan.  Their  point  of  view  is  strengthened  by  the  acknow- 
ledged fact,  that  the  whole  Laurentian  country  from  Lake 
Superior  to  the  shores  of  Labrador,  northern  New  York 
and  much  of  New  England  is  traversed  by  vast  dykes  of 
massive  (unstratitied)  syenite  and  granite  cutting  the 
bedded  rocks  and  each  other  in  all  directions  both  vertical 
and  horizontal.  Such  masses  or  dykes  of  unstratified  rock 
in  the  highlands  of  New  Jersey  have  already  been  re- 
ferred to.f 

At  Kennedy's  granite  quarry,  in  Delaware  county. 
Radnor  township,  near  Wayne  station  (a  good  photo- 
graphic view  of  which  is  given  on  plate  XXXVIII  of  Re- 
port of  Progress  05).  no  stratification  can  be  made  out  by 
the  eye,  and  the  syenite  mass  looks  like  an  eruption  from 
below. 

In  strong  contrast  to  this  is  the  fact  that  at  the  Leiper 
"granite"  quarries,  so  called,  in  Ridley  township  (shown 
in  plates  16  to  22  of  the  same  report.)  the  original  sedi- 
mentary stratification  is  unmistakable.  But  here  we  are  in 
another  system  of  rocks  which  has  no  certain  connection 
with  the  Laurentian,  as  will  be  seen  hereafter. 

How  much  of  the  Laurentian  system  is  sedimentary  and 
how  much  of  it  volcanic  may  never  be  exactly  defined;  but 
the  mere  fact  that  one  kind  of  rock  can  be  seen  cutting  or 
penetrating  the  other  is  the  strongest  argument  for  the  gen- 
niness  of  both,  in  spite  of  opposite  theories  of  the  general 

*Rhyolitic,  from  the  Greek  verb  rhein,  to  flow. 
fThe  granite  of  Richmond,  Va.,  is  of  this  kind. 

7 


98  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

origin  of  the  whole,  and  in  spite  of  any  revelations  which 
have  been  or  may  hereafter  be  made  by  the  microscope  ; 
with  regard  to  which  last,  it  may  be  also  said,  that  the 
microscopic  examination  of  a  transparent  slice  of  azoic 
rock  may  lead  two  observers  to  opposite  conclusions  under 
the  influence  of  two  opposite  prejudices,  the  one  believing 
at  the  outset  that  his  specimen  comes  from  a  volcanic  rock, 
the  other  that  it  is  from  an  original  sediment  subsequently 
metamorphosed. 

The  argument  from  olivine. 

A  case  in  point  occurs  in  Mr.  F.  D.  Adams'  report  to  the 
Canada  survey  (in  1885)  on  microscopic  inspection  of  thin 
sections  of  a  labradorite  rock  from  the  Upper  Saguenay 
river,  flowing  through  the  typical  Norian  region.  In  the 
sections  he  could  see  grains  of  olivine,  each  having  two 
skins,  an  inner  of  pyroxene  (?)  and  an  outer  of  actinolite 
(or  hornblende),  the  whole  being  encased  in  a  matrix  of 
lime-soda  feldspar.  The  rock  at  large,  from  which  the 
sections  were  made,  was  composed  of  lime-soda  feldspar, 
olivine  and  some  scattered  grains  of  titaniferous  (?)  iron 
ore.  Now  since  olimne*  is  one  of  the  universally  recog- 
nized volcanic  glasses,  abundantly  expelled  from  modern 
volcanoesf ;  and  since  it  is  of  frequent  occurrence  also  in 
older  lavas,  basalts  and  trap  dykes,  both  in  the  form  of 
grains  and  small  masses,  long  crystals  and  balls;  and  since 
its  golden-colored  transparent  crystals  (chrysolite)  also  is 
found  in  modern  and  recent  lavas, \  the  conclusion  has  been 
drawn  that  the  Saguenay  rock  formations  taken  as  a  whole 
have  been  originally  in  a  molten  condition,  and  that  the 
olivine  grains  were  the  lirst  to  solidify  while  the  envelop- 
ing feldspar  mass  was  still  in  the  condition  of  molten  glass; 
in  other  words,  that  the  silicate  of  magnesia  solidified  in 

*A  pale  olive  green  opaque  silicate  of  magnesia  and  iron  (^3  sil.,  ^  mag. 
and  ^  iron. 

fSee  especially  accounts  of  the  Hawaiian  islands,  and  of  the  Challenger 
dredgings  in  the  Pacific. 

jThose  found  in  sand  at  Expailly  in  France  (Dana)  probably  came  from 
the  Auvergnese  basaltic  beds. 


THE   ARGUMENT   FROM   OLIVINE.  99 

grains  first,  and  the  silicates  of  lime  and  soda  as  the  sur- 
rounding rock  afterwards.  The  enveloping  zones  or  skins 
of  each  olivine  grain  seen  under  the  microscope  would  then 
be  the  products  of  a  slow  subsequent  process,  by  which  the 
surface  of  each  grain  (silicate  of  magnesia  and  lime)  lost 
some  magnesia  and  became  ^.pyroxene  or  augite  ;  while  the 
surface  of  the  enveloping  feldspar  gained  some  magnesia 
and  became  an  actinolite  or  hornblende  (silicate  of  mag- 
nesia, lime  and  iron);  both  the  inner  zones  of  pyroxene  and 
the  outer  zone  of  actinolite  being  minutely  crystallized  in 
tibers  crosswise.  Similar  grains  with  double  skins  (the 
outer  hornblende)  were  described  by  Tornebohm,*  as  seen 
in  Swedish  gabbro  rock  (an  ancient  crystalline,  granite-like, 
magnesia-lime-soda  lava)  the  feldspar  of  which  is  usually 
taken  to  be  labradorite,  and  some  varieties  of  which  contain 
an  abundance  of  olivine.  f 

It  is  easy  enough  to  see  how  a  grain  of  strongly  mag- 
nesian  silicate  might  act  on  and  be  affected  by  its  en- 
velope of  lime-soda  silicate  to  produce  in  time  intermedi- 
ate skins  or  shells  of  magnesia-lime-soda  silicate  by  the 
gradual  mixing  of  the  three  elements  along  the  contact 
surfaces.  But  it  is  a  risky  thing  to  dogmatise  an  opinion, 
1,  as  to  how  the  grains  were  first  formed,  and  2,  as  to  the 
nature  of  the  action  and  reaction  between  the  grain  and  its 
envelope.  While  it  may  be  safely  accounted  probable  that 
the  magnesia  was  concentrated  by  the  fiery  fusions  of 
the  mass;  and  while  it  seems  almost  positively  certain  that 
the  fibrous  zones  could  not  have  been  cross  crystallized 
around  the  grains  until  after  they  had  been  fully  formed; 
we  know  too  much  of  cold  aqueous  concretionary  structure 
in  sedimentary  rocks  (e.  g.  oolites  in  the  magnesian  lime- 
stones of  No.  ItJ:)  not  to  make  the  aqueous  formation  of 
the  olivine  grains  a  possibility.  And  then,  the  aqueous 
alterations  of  minerals  seen  going  on  at  a  low  tempera- 
ture in  the  hardest  crystalline  rocks,  at  all  depths  of  per- 
meation, suggests  the  possibility  of  the  cold  aqueous  for- 
mation of  the  skins  of  the  olivine  grains. 

*Neu.  Lehr.  fur  Min.,  1877,  page  303,  Adarns. 
t  A.  Geikie's  Text  Book  of  Geol.,  page  150,  1882. 
JCambro  Silurian. 


100  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

The  granular  condensation  of  the  overcharge  of  magnesia 
in  a  magnesian  silicate  mass  is  illustrated  by  Dr.  F.  A. 
Genth's  discovery  in  1874  that  grains  of  chrysolite  are  dis- 
seminated throughout  the  whole  mass  of  bronzite  (iron- 
bearing  enstatite)  forming  Castle  Rock  in  Delaware  county.* 
The  bronzite  mass  is  a  silicate  of  magnesia  and  iron  (57, 
36,  6).  But  the  grains  of  chrysolite  have  twice  as  much 
magnesia  and  iron  to  the  silica  as  the  rock  has  which  en- 
velops them.  In  studying  Castle  Rock  repeatedly  I  could 
not  quite  convince  myself  that  it  is  stratified,  and  there- 
fore do  not  deny  that  it  may  be  a  volcanic  dyke.  Bur  on 
the  other  hand  it  is  an  integral  part  of  the  long  belt  of  ser- 
pentine strata  which  crosses  the  county;  therefore  it  ought 
to  be  sedimentary.  But  this  belt  of  Delaware  county  ser- 
pentine rocks  does  not  belong  to  the  older  gneisses;  it  be- 
longs to  the  mica  schist  series  to  be  discussed  hereafter; 
therefore,  the  question  of  the  volcanic  origin  of  Castle 
Rock  does  not  directly  affect  any  question  respecting  the 
stratification  of  the  older  syentte  belt  which  passes  just 
north  of  it. 

The  point  to  keep  in  view  is  this,  that  the  genuineness  of 
the  stratification  of  the  older  gneiss  rocks  is  not  impugned 
by  any  amount  of  volcanic  disturbance  and  intrusion  to 
which  they  may  have  been  subjected;  nor  by  any  number 
of  massive  granite  dykes,  bosses  or  layers  of  gabbro;t  nor 
by  any  amount  of  olivine  discoverable  in  the  area  of  coun- 
try which  they  occupy. 

The  scarcity  of  olivine  in  the  older  gneisses  can  be  appre- 
ciated from  the  fact  that  in  the  long  course  of  the  history 
of  the  geological  survey  of  Canada  its  accomplished  chem- 
ist and  mineralogist,  Dr.  Hunt,  never  saw  (or  at  least  never 
reported  finding)  olivine  in  the  Norian  gneisses,  although 
he  found  it  in  some  (Norian  ?)  boulders  in  New  Hampshire 
which  were  supposed  to  have  come  from  Canada  in  the  ice 
age.:}:  When  Mr.  Adams  says  that  it  "occurs  abundantly 

*Report  of  Progress  B,  page  163. 

fSuch  as  the    Gabbro  formation    of    Lake  Superior,  which,  however,  is 
placed  above  the  gneiss  by  western  geologists. 
JAdams,  Am.  Nat,  Nov.,  18a5,  page  1088. 


THE  ARGUMENT   FROM    SERPENTINE.  101 

in  the  anorthosite  of  many  parts  of  the  Sagnenay  area," 
and  that  he  has  found  it  also  in  a  hand  specimen  from  old 
rocks  near  Dolin's  lake  in  New  Brunswick,  such  discoveries 
leave  the  question  of  the  aqueous  or  igneous  origin  of  the 
great  gneiss  formation  as  a  whole  still  unanswered;  for  it 
is  supposable,  and  will  be  to  many  minds  probable,  that 
the  observed  occurrences  of  olivine  are  referrable  in  all 
cases  to  dykes  or  layers  or  bosses  of  igneous  rock  ejected 
through  and  between  the  recrystallized  sedimentary  gneiss 
beds,  and  not  to  the  constitution  of  the  gneiss  itself. 

The  argument  from  serpentine. 

It  is  needless  to  discuss  the  vexed  question  of  the  origin 
of  serpentinous  rocks  if  we  recognize  the  fact  that  they 
may  be  of  various  kinds  and  have  more  than,  one  origin  ; 
some  of  them  being  sedimentary,  others  volcanic,  and  yet 
imitating  each  other  in  the  same  way  as  the  granite  gneisses 
and  granites  imitate  each  other. 

In  Pennsylvania  we  have  no  notable  serpentine  beds  in 
the  Highland,  Welsh  mountain,  Buck  ridge,  Delaware 
county  older  gneisses.  A  discussion  of  the  serpentine  beds 
of  the  mica  schist  series  on  the  Schuylkill  and  west  of  it 
would  properly  find  its  place  in  describing  that  series. 
But  as  Mr.  T.  D.  Rand  has  argued  in  the  most  forcible 
manner  for  the  assignment  of  these  serpentines  to  a  place 
in  the  older  gneiss  series,  not  only  in  Delaware  county,  but 
also  in  Northampton  county,  it  is  better  to  give  the  facts 
here.  In  the  proceedings  of  the  Academy  of  Natural 
Sciences  of  Philadelphia,  November  24,  1886,  pages  393, 
407,  and  in  the  annual  report  of  the  geological  survey  of 
Pennsylvania  for  1887,  Mr.  Rand's  views  may  be  found  with 
illustrative  maps  and  sections. 

Of  the  two  parallel  serpentine  belts  that  cross  the 
Schuylkill  river  (1)  above  and  (2)  below  Lafayette  station, 
the  (2)  belt  (with  steatite}  cannot  be  traced  (west)  beyond  a 
bend  in  the  Black  Rock  road  (one-half  mile  north  of  the 
P.  R.  R.)  The  first  belt  is  conspicuous  at  Rosemont 
station  (P.  R.  R.),  but  no  farther.  A  (3)  belt  commences 

LIBRARY 
UNIVERSITY  OF  CALIFORNIA 

SANTA   RARRARA 


102  GEOLOGICAL   SURVEY    OF   PENNSYLVANIA. 

on  Meadow  brook  f  mile  east  of  Darby  creek  and  runs  on 
westward.  It  was  always  doubtful  to  which  belt  (1)  or  (2) 
this  should  be  assigned.  In  1885  Mr.  T.  D.  Rand*  "found  a 
distinct  outcrop  on  the  Roberts  road,  on  the  property  of 
Colonel  Joseph  F.  Tobias,  or  of  Dr.  E.  H.  Williams,  with 
fragments  in  the  soil  of  the  former  to  the  northeast.  The 
belt  is  very  narrow,  arid  the  valley  of  a  small  creek  seems 
to  occupy  nearly  the  same  line."  The  outcrop  is  about 
half-way  between  the  Rosemont  (1)  exposure  and  the 
Meadow  brook  (3)  exposure  and  seems  to  settle  the  ques- 
tion, f 

The  Edgehill  (eurite)  rock  seems  to  outcrop  100'  to  200' 
from  the  serpentine  on  the  Roberts  road.  The  two  occupy 
here  the  same  relations  as  they  do  near  Radnor  station,  on 
the  other  (N.)  side  of  the  Laurentian  axis. 

The  Delaware  county  serpentines. 

Castle  rock,  four  miles  north  of  Media,  in  Delaware 
county,  is  a  confused  mass  of  plates  of  that  species  of 
enstatite  rock:}:  which  contains  iron  (bronzite)  and  which, 
after  imbibing  water  (chemically)  turns  into  serpentine 
rock  (composed  chiefly  of  silica  and  magnesia. )§  On  the 
eastern  side  of  a  brook  flowing  south  there  are  outcrops  of 
serpentine  which  indicate  the  continuance  of  the  mineral 
towards  the  Schuylkill ;  but  at  the  west  end  of  the  Castle 

*Strike  N.  30°  E.,  dip  50°  S.  60°  E.  ;  mica  schist,  adjacent,  strikes  N.  40° 
E.,  dip  6508.50°  E. 

fThis  outcrop  is  somewhat  south  of  the  Kosemont  outcrop  line  and  indi- 
cates some  change  in  strike,  or  a  throw,  or  an  echelon  structure. 

Jin  Bucks  county,  near  the  Neshaminy,  between  Scottsville  and  Rock- 
ville,  at  Vanarsdalen's  quarry  of  crystalline  limestone  (interbedded  with 
hornblendic  gneiss  and  charged  with  plumbago)  among  the  numerous 
species  of  crystals  some  contain  percentages  of  magnesia,  but  none  come 
under  the  head  of  magnesian  silicates  proper.  (Report  B).  Near  the 
mouth  of  the  creek,  at  Flushing  is  an  outcrop  of  enstatite  rock,  bedded  and 
dipping  10°,  the  relations  of  which  are  not  understood.  (Report  C6,  p.  60.) 

§Mr.  Salom,  when  Dr.  Genth's  pupil,  found  that  between  5  and  10  per  cent 
of  the  Castle  rock  was  soluble  in  dilute  chlorhydric  acid,  and  composed  of 
silica,  45 ;  mag.,  31.6  ;  ferrous  oxide,  19.4 ;  lime,  3.9,  representing  dissemi- 
nated grains  of  chrysolite;  the  insoluble  90  to  95  per  cent  was  composed  of 
silica,  56;  mag.,  29;  ferrous  ox.,  12;  lime,  1.2,  closely  agreeing  with  the 
composition  of  bronzite.  Genth's  Rep.  B,  1875,  p.  64. 


THE   ARGUMENT   FROM   SERPENTINE.  103 

rocks  a  cultivated  outspread  of  gneiss  land  soil  shrouds  the 
geology  of  this  singular  place  in  mystery.* 

There  is  a  range  of  abandoned  quarries  extending  from 
Media  W.  S.  W.  past  Lenni  for  miles,  f  Other  ranges  tra- 
verse the  county.  C.  E.  Hall's  sketch  map  in  C4,  preface 
page  v,  shows  more  than  50  spots  marked  serpentine.  It 
is  noteworthy  that  no'ne  of  them  are  in  the  Older  (syenitic, 
liornblendic)  gneiss  regions.  All  of  them  are  in  the  interval 
regions  of  Newer  (micaceous)  gneiss,  the  equivalent  of  the 
Philadelphia  belt.  Nor  are  any  of  them  in  the  South  Valley 
Hill  belt  of  mica  slate. :{: 

The  Chester  county  serpentines. 

Serpentine  outcrops  are  very  numerous  in  Chester  county. 
Thirteen  are  enumerated  in  Report  04,  pages  62,  63.  Brin- 
ton*  s  quarry  is  a  grand  exhibition  of  serpentine,  and  from 
this  quarry  500,000  cubic  yards  of  the  rock  had  been  taken 
before  1880,  the  largest  being  3  feet  square  and  16  feet  long. 
In  1880  6,000  cubic  feet  of  rock  were  moved,  valued  at 
$10,000. 

Dr.  Frazer  makes  the  general  remark  that  "the  serpen- 
tine under  no  consideration  has  any  direct  connection  with 
the  series  of  hypozoic  and  palaeozoic  strata,  or  strata  of  pri- 
mary origin.§ 

The  serpentines  near  Baltimore  are  said  to  furnish  under 
the  microscope  ample  evidence  that  originally  they  were 

*Mr.  E.  B.  Harden  has  made  for  me  photographic  pictures  of  the  mass  as 
it  appears  on  all  sides  and  in  various  lights.  I  have  myself  made  a  careful 
contour  line  map  of  it,  with  pencil  sketches ;  but  I  could  come  to  no  certain 
conclusion  whether  its  apparrent  bed-plates  were  or  were  not  cleavage 
planes.  It  may  be  synclinal,  or  it  may  be  a  dyke. 

fSee  also  notes  on  the  minerals  of  the  county  by  Col.  Joseph  Willcox,  in 
C4,  p.  346. 

{Mr.  Hall  and  Mr.  Rand  are  thus  directly  opposed  in  their  structural 
views  respecting  the  Serpentine.  Dr.  Frazer  agrees  with  Mr.  Hall  in  iso- 
lating the  Serpentine  from  the  Archaean,  but  he  advocates  its  connection  with 
the  hydromica  and  chlorite  series. 

§Report  04,  page  289.  Prof.  Rogers  notes  serpentinous  geodes  in  the 
Welsh  mountain  gneiss,  at  Warwick  mines,  Report  C4,  page  238.  Fine 
specimens  of  serpentine  have  been  found  in  the  mines  on  Fritz's  island  near 
Reading,  at  Topton,  and  at  the  Wheatfield,  Boyerstown,  Ruth  and  Jones 
mines  in  Berks  county;  but  no  serpentine  beds.  See  Reports  D2  and  D3. 


104  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

trap  dykes,  holding  a  rhombic  pyroxene,  with  or  without 
olivine.  * 

A  similar  conclusion  was  reached  by  Prof.  F.  D.  Chester, 
of  Dover,  Delaware,  in  studying  the  large  belt  of  serpen- 
tine on  the  state  line  in  Chester  county;f  and  he  was  led  to 
regard  all  the  serpentines  of  Chester  county  as  alterations 
of  rocks  containing  a  rhombic  pyroxene,  either  enstatite 
or  bronzite.  The  great  mass  of  Castle  rock,  unchanged 
enstatite  rock  in  Delaware  county  can  be  seen  passing  on 
eastward  as  a  serpentine  outcrop. 

The  Lancaster  county  serpentine. 

The  two  remarkable  belts  of  serpentine  in  southern  Lan- 
caster, passing  over  into  Maryland,  are  described  in  detail 
by  Dr.  Frazer  in  his  Report  C3,  pages  26,  89,  177,  190. 
Wood's  celebrated  chrome  mine  is  in  the  southern  belt 
in  an  oxbow  of  Octoraro  creek  just  within  Little  Britain 
township.  In  Fulton  township  the  serpentine  ridges  are 
called  "barrens."  Up  to  1877  about  90,000  tons  of 
chrome-iron  ore  had  been  taken.  The  mine  was  then  720 
feet  deep  and  yielded  500  or  600  tons  of  the  ore  annually. 
The  serpentine  country  through  which  the  ore  vein  runs  is 
unstratified  and  about  three  quarters  of  a  mile  in  breadth. 
The  ore  strikes  S.  78°  W.  The  sandy  chlorite  slates  to  the 
north  of  the  mine  dip  S.  50°.  The  rocks  southeast  of  the 
mine  are  hornblendic,  and  "  a  region  of  syenite  commences 
on  that  side  "(Glenn).  The  same  kind  of  difficulty  here 
encounters  the  geologist  as  in  Northampton  county, 
whether  he  is  disposed  to  connect  the  serpentine  structur- 
ally with  the  older  hornblendic  gneiss  (syenite)  system,  or 
with  the  newer  gneiss  (mica  schist)  system,  or  with  the 
still  later  chloritic  (phyllite)  system. 

*Dr.  G.  H.  Williams,  of  the  Johns  Hopkins  University,  on  the  Peritodites 
and  Serpentines  of  Baltimore. 

t Letter,  Oct  23,  1886.  The  mother  rock  of  this  belt  appears  to  consist  of  a 
rhombic  pyroxene,  probably  bronzite,  associated  with  a  variable  amount  of 
diallage,  both  minerals  largely  altered  intolightamphibole  aggregates,  gen- 
erally tremolite,  partly  actinolite  ;  and  these  are  found  in  all  stages  of  alter, 
nation  into  a  true  chrome-serpentine,  the  direct  product  of  alteration  of 
pyroxene,  as  described  by  Drasche  in  the  Tyrol. 


THE   ARGUMENT   FROM   SERPENTINE.  105 

The  Northampton  county  serpentine. 

The  serpentine  of  the  old  Wolf  quarry  of  Chestnut  Hill, 
Northampton  county,  seems  to  be  not  an  originally  bedded 
deposit,  like  limestone,  but  an  alteration  product  in  the 
white  tremolite*  quarry-rock  (belonging  to  the  hornblendic 
or  amphibole  gneiss  series),  composed  chiefly  of  silicate  of 
magnesia  and  lime.  The  silicate  of  magnesia  after  im- 
bibing water  has  separated  from  the  mass  into  veins  and 
lumps  and  scattered  pseudomorph  crystals  of  pure  serpen- 
tine. The  lime  has  also  separated  in  the  iorm  of  veins  and 
masses  of  snow-white  crystalline  carbonate  of  lime  (calcite). 
It  is  possible  to  trace  on  the  face  of  the  quarry,  in  the 
space  of  a  few  inches,  the  gradual  transformation  of  the 
pure  white  tremolite  rock  into  a  mixed  stone,  composed 
mainly  of  serpentine,  tremolite  and  calcite.  The  steps  of 
the  process  is  observable  in  the  thin  slices  under  the  micro- 
scope, the  tremolite  crystals  being  broken  up  into  bundles 
of  fibres  traversed  by  irregular  canals  of  serpentine.^ 

It  was  always  an  interesting  question  whether  the  ser- 
pentine beds  of  Chestnut  hill  belonged  to  the  Highland 
gneiss  or  to  the  limestone  of  the  valley ;  \  but  Mr.  Rand 
seems  to  have  set  the  matter  at  rest  by  his  observations  in 
the  gap  of  the  Delaware  above  Easton  and  in  the  gap  of  the 
Bush  kill  west  of  the  river.  § 

Five  soapstone  (steatite}  outcrops  are  exposed  and  four 
of  them  have  been  quarried,  all  dipping  steeply  southward 
enclosed  between  solid  ribs  of  gneiss  one  or  two  hundred 
feet  thick.  | 

*See  Genth's  Report  B,  1874,  page  67.  On  page  64  he  notes  that  the  "  Wal- 
lastonite  "  of  Easton  is  tremolite. 

|G.  P.  Merrill,  in  Proc.  U.  S.  National  Musenm,  Vol.  VII,  1890,  page  600, 
where  an  analysis  of  the  tremolite  by  Eakins  is  given  :  Sil.  58 ;  Mag.  26  ; 
Lime  12  ;  Alum.,  Potash,  Sod  4. 

jSee  Rogers'  Geol.  Penn.,  1858,  Vol.  1,  p.  94,  and  Report  D3,  Vol.  1,  1883,  p. 
79. 

§T.  D.  Rand.  Notes  on  the  genesis  and  horizons  of  the  Serpentines  of  S. 
E.  Pa.  in  Proc.  Acad?  Nat.  Sci.,  Phila.,  March  25,  1890,  page  95. 

II  South-dipping  rnagnesian  limestone  outcrops  border  the  river  for  a  mile 
above  Easton  to  within  200  feet  of  the  first  exposed  steatite  or  talc-slate  bed, 
which  is  not  thick,  has  no  visible  hanging  wall,  but  a  foot- wall  of  gneiss. 
The  second  one  is  immediately  below  the  first  and  in  the  gneiss  ;  one  mass 


106  GEOLOGICAL   SURVEY    OE   PENNSYLVANIA, 

Chestnut  hill  is  the  western  end  of  one  of  the  Highland 
ranges  of  New  Jersey,  severed  by  a  steep  and  picturesque 
gap  cut  through  it  by  the  river.  Its  beds  of  gneiss  dip  all 
one  way,  southward,  as  the  limestone  beds  do  to  the  south 
of  it.  There  is  no  appearance  of  anticlinal  structure  in  the 
ridge.*  Its  crest,  straight  and  sharp,  is  made  by  a  massive 
rib  of  gneiss,  dipping  at  the  river  .31°;  at  its  highest  point 
(700'  A.  T.)  59°,  on  the  road  30°,  at  the  Bushkill  gap  40°, 
43°,  48°,  60°,  further  west  28°,  all  southeast ;  no  northwest 
dips  anywhere,  until  its  western  point  sinks  beneath  the 
around-lapping  limestone  country,  the  nearest  outcrop  of 
which  dips  12°  S.  W.  That  the  whole  ridge  is  a  mono- 
clinal  uplift  is  confirmed  by  the  first  limestone  dip  (28°,  N.) 
seen  at  the  Bushkill  gap  abutting  against  the  lowest  visible 
gneiss  dipping  48°,  S.  E. f  The  talc-schist  or  soapstone  beds, 
and  the  serpentine  (picrolite)  beds  are  not  of  the  age  of 
valley  limestones  (magnesian  though  many  of  these  be)  but 
belong  to  the  more  ancient  gneiss  formation  of  the  South 

of  it  among  many  (5'-6'  long)  nearly  pure  talc  schist  at  one  end,  at  the 
other  apparently  unaltered  qartzose  gneiss.  Two  hundred  feet  north  of 
the  second  appears  the  third,  quarried  for  100'  up  the  slope ;  both  walls 
gneiss,  fallen  blocks  of  the  hanging  wall  showing  change  from  granulite  to 
steatite.  The  fourth  and  much  larger  one  is  300'-400'  further  north  ;  inter- 
val, all  (?)  gneiss.  The  fifth  200'-300'  further  north ;  interval  all  gneiss, 
<one  rib  very  massive,  making  overhanging  cliffs,  has  been  much  quar- 
ried). Beyond  this,  more  gneiss  ;  dips  obscure,  but  nearly  vertical ;  hill 
crest  more  than  400  above  the  river.  Incredible  that  these  four  outcrops 
should  be  tightly-compressed  synclinal  folds  of  a  talc  schist  formation  over- 
lying the  gneiss.  They  must  be  conformably  interbedded  layers  in  the 
(  Lauren  tian)  gneiss.  (Rand.) 

*A11  this  is  noted  on  Prime's  admirable  contour-line  map  of  Northampton 
county  in  Atlas  to  D3,  Vol.  1,  1883,  sheets  1  and  2. 

fit  is  not  absolutely  necessary  to  suppose  an  upthrow  fault  along  the 
northern  base  of  the  ridge,  for  a  28°  dip  would  shoot  the  limestone  high  over 
the  ridge.  Nor  is  it  a  mere  "brushed  up"  dip,  for  all  the  observed  limestone 
dips  along  the'Bushkill  for  a  mile  up  (and  along  the  Delaware  as  far)  are  in 
the  same  N.  W.  direction,  towards  a  synclinal  axis  of  considerable  length. 
Although  the  ridge  itself  is  a  very  ancient  eroded  monoclinal,  it  became  the 
core  of  a  subsequent  overarching  limestone  anticlinal,  which  included  all 
the  Lower  Silurian  formations,  probably  the  Upper  Silurian  series  also,  anil 
possibly  the  whole  Palaeozoic  system  to  the  top  of  the  Coal  Measures.  There 
has  been  tire*  enough  since  the  Coal  Age  to  remove  it  all,  and  exhibit  once 
more  the  original  pre-Silurian  or  pre-Cambrian  topography. 


THE   AEGUMENT   FROM    LABRADORITE.  107 

mountain  highlands  whatever  it  may  be.*  And  this  agrees 
with  all  Mr.  Rand's  observations  of  the  serpentines  of  Del- 
aware and  Chester  counties,  which  he  shows  pretty  clearly 
to  be  interbedded  among  the  ancient  gneisses  of  that 
region. 

On  the  other  hand,  the  serpentine  belts  of  Lancaster 
county  and  Maryland  are  assigned  both  by  Frazer  and 
Keyes  to  the  phyllite  system  of  rocks,  which  belong  to  the 
Philadelphia  belt  of  newer  gneiss  ;  and  the  serpentine  and 
steatite  of  the  Schuylkill  are  placed  by  Rogers  and  C.  E. 
Hall  at  the  top  of  that  newer  gneiss  system. 

In  Newfoundland,  as  in  Pennsylvania,  no  extensive  dis- 
play of  serpentine  is  known  in  the  Laurentian  system,  nor 
is  crystalline  limestone  found.  Lime,  magnesian  minerals, 
and  mica  are  remarkably  absent  from  the  great  overlying 
•formation  (Huronian) ;  lime  showing  only  in  cross  veins, 
and  magnesia  only  at  one  place,  as  steatite  and  asbestos,  in 
seams.  Guided  by  the  fossils  Mr.  Murray  came  to  the 
conclusion  that  the  serpentine  formation  overlaid  the 
Levis  (Quebec  group)  and  were  overlaid  by  the  Hudson 
river  group,  etc.  unconformably,  so  that  they  were  even 
overlaid  in  places  by  Devonian.  This  possible  identity  of 
the  Newfoundland  serpentine  formation  with  our  great 
magnesian  limestones  (No.  II.  Chazy?)  would  bring  it  into 
the  neighborhood  of  the  Northampton  county  serpentine 
beds,  north  of  Easton.f 

Genthite  has  been  found  at  the  Lafayette  soapstone 
quarries,  in  small,  bright,  emerald  green  crusts,  showing 
its  characteristic  stalactitic  structure.  This  proves  the 
presence  of  nickel  in  our  serpentines.:}: 

The  argument  from  labradorite. 
Labradorite  rocks  are  unknown  among  our  older  gneisses 

*Another  good  argument  both  for  this  and  also  for  the  monoclinal  struc- 
ture of  Chestnut  ridge,  is  the  fact  that  no  serpentine  or  talcschist  or  steatite 
is  to  be  seen  anywhere  along  the  northern  side  of  theridge,  or  at  its  north- 
ern base. 

t  Alex  Murray,  Canada  survey,  in  Geol.  Mag.,  March,  1879,  p.  139. 

}H.  C.  Lewis,  May  12,  1885,  in  report  of  Acad.  N.  S.  Philada.  meeting  in 
Amer.  Nat.,  Sept.,  page  929. 


108  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

in  Pennsylvania;  and  about  this  it  is  necessary  to  say  some- 
thing. 

The  eastern  range  of  the  Canadian  mountains,  through 
Labrador  to  the  ocean  shore,  is  a  country  of  massive  and 
schistose  gneisses,  many  of  which  are  made  up  of  quartz 
and  labradorite  feldspar. *  This  feldspar  is  essentially  a 
silicate  of  alumina,  lime  and  soda  (53  :  30  : 12  :  5),  and  might 
be  formed  in  a  metamorphosed  sediment  just  as  well  as  any 
other  feldspar,  provided  the  drainage  of  that  sediment  was 
from  a  limestone  region.  It  is  a'frequent  constituent  of 
modern  volcanic  lavas,  and  is  found  also  in  some  ancient 
trap-dykes  and  porphyries;  but  so  are  several  other  feld- 
spars. It  is  in  itself  no  proof  of  the  plutonic  origin  of  the 
East  Canada  gneisses. 

It  is  still  a  question  what  relation  in  time  the  great  Lab- 
radorian  (Norwegian  or  Norian)  system  of  gneisses  holds 
to  the  West  Canada  Laurentian  (Ottawa  or  Granville)  sys- 
tem of  gneisses. 

Now,  although  the  Norian  rocks  are  commonly  called 
Upper  Laurentian,  it  is  possible  to  consider  them  as  two 
geographical  areas  of  one  and  the  same  system;  in  which 
case  the  abundance  of  labradorite  feldspar-^  in  the  eastern 
area  would  be  an  accident  of  drainage.  On  any  other 
hypothesis  it  is  difficult  to  explain  the  absence  of  labrado- 
rite gneiss  from  the  range  of  the  New  York,  New  Jersey  and 
Pennsylvania  highlands  ;  for  it  looks  as  if  we  had  in  this 
range  the  upper  part  of  any  Laurentian  system  which 
could  be  established  on  anything  like  a  sedimentary  basis 
of  argument. 

The  argument  from  marble. 

White  crystalline  limestone  beds  are  interleaved  with 
the  gneiss  rocks  of  the  New  Jersey  highlands  all  along 
their  northwest  border,  and  some  are  pure  marbles  (96.50  : 
1.13  : 1.30  :  0.30) ;  others  nearly  pure  dolomites  (53.00  : 
42.26.  3.50  alum,  sfnttox.  iron  :  0.50  silica  and  insoluble). ^ 

*With  hornblende,  hypersthene  and  magnetic  iron. 

fOr  rather  of  the  whole  group  of  plagioclase  (soda  and  lime)  feldspars. 

{Cook's  An.  Rt,  1864,  page  15. 


THE   ARGUMENT   FROM   MARBLE.  109 

Prof.  James  Hall,  however,  published  at  the  Albany 
meeting  of  the  A.  A.  A.  S.,  in  1876,  his  opinion  that  the 
crystalline  limestones  of  northern  New  York  are  no  part 
of  the  Laurentian  system,  but  are  of  later  age.* 

The  azoic  marble  beds  of  New  Jersey  furnish  precious  in- 
formation for  studying  those  of  Pennsylvania. 

In  Warren  county,  N.  J..  at  Lower  Harmony  are  exten- 
sive quarries.  An  acre  of  marble  was  exposed  in  1871, 
without  penetrating  more  than  15'  of  strata;  indistinctly 
dipping  steep  S.  E.;  gray,  in  some  places  banded  with  al- 
ternate dark  and  light  lines;  with  scattered  nodules  and 
masses  of  soapstone  (steatite)  and  hornblende;  some  graph- 
ite ;  a  very  little  pyrites  in  places.  In  the  deepest  parts  of 
the  pit  the  stone  is  more  solid  and  free  from  these  min- 
erals, f 

In  the  Jenny  Jump  range  of  highlands  the  Rose  Crystal 
Marble  quarry  (50x50x25  yards  deep)  have  exposed  30' 
of  rose-colored  marble  beds,  dipping  80°  N.  75°  W. 
Quarry  beds,  white,  flesh-colored,  rose-colored;  with  green- 
black  hornblende,  black  mica  and  occasional  crystals  of 
black  tourmaline  ;  calcite  predominates  largely  ;  stone  can 
be  burned  for  lime;  polishes  well,  showing  the  other  min- 
erals ;  blocks  8'x3'x2'  got  free  of  seams  or  joint  flaws. 
The  overlying  beds  (to  the  west)  are  pearl  gray.  The 
underlying  beds  (to  the  east,  100'  thick  as  exposed  are 
ordinary  white  limestone,  none  colored.* 

Two  belts  of  azoic  white  crystalline  limestone  or  marble 
traverse  New.  Jersey  in  its  Highlands.  The  Pequest  belt 
has  beds  so  thick  and  persistent  that  it  can  be  located  by 
color  on  the  geological  map  of  New  Jersey;  and  its  rare 
and  beautiful  minerals  are  fully  described  in  the  geology 
of  New  Jersey. §  The  Ramapo  belt  is  smaller  and  remark- 
able for  containing  serpentine  everywhere,  in  such  quan- 
tities (in  places)  as  to  spoil  the  limestone  for  lime -burn - 

*See  Amer.  Jour.  Science.  See  also  C.  E.  Hall's  report  on  the  Adirondack 
rocks  ("Laureutian  magnetic  iron  ore  deposits  of  N.  N.  Y.")  with  a  geol. 
mapof  Essex  Co.  in  Rt.  of  State  Geologist  for  1884  (No.  161,  page  31). 

fCook  An.  Rt.,  1872,  page  26. 

jCook  An.  Rt.,  1872,  pages  27,  28. 

§1868,  pages  309,  326. 


110  GEOLOGICAL   SURVEY    OF   PENNSYLVANIA. 

ing;  both  massive  and  also  fibrous  (cTtrysotile),  especially 
both  at  Mountville  and  also  near  Winokie. 

This  union  of  serpentine  with  marble  shows  two  things: 
1,  that  the  azoic  lime  deposits  were  in  part  highly  magne- 
sian,  and,  2,  that  they  were  in  part  highly  siliceous. 
Under  favorable  circumstances  the  hydrous  silicate  of  mag- 
nesia (serpentine)  has  been  generated  in  small  quantities 
in  our  mixed  magnesian  and  non-ma gnesian  limestone  beds 
of  No.  II.* 

The  sedimentary  origin  of  the  azoic  marble  beds,  as  or- 
dinary lime-magnesia  muds,  can  hardly  be  doubted. 

Included  beds  of  syenite-gneiss  in  the  body  of  the  marble 
mass  and  regularly  inter  stratified,  with  the  marble  beds 
complete  the  proof,  and  carry  the  conclusion  one  step 
further,  that  the  gneiss  was  itself  also  an  ordinary  mixed 
sand-mud  deposit,  like  all  the  sandy  shale  and  sand  rocks 
of  after  ages  which  have  remained  uncrystallized  merely 
because  they  have  not  been  subjected  to  the  proper 
process. 

In  Pennsylvania  the  Highland  gneiss  areas  do  not  show 
their  marble  beds  enough  to  be  well  studied.  The  beds  are 
not  thick  enough  to  encourage  mining  in  competition  with 
the  marble  quarries  of  No.  II  along  the  Chester  valley.  But 
where  they  are  thus  exposed— in  southern  Chester  county 
— they  reveal  the  same  facts  as  in  the  New  Jersey  High- 
lands', f 

In  New  Jersey  the  Pequest  marble  belt  has  been  so  ex- 
tensively quarried  that  the  story  is  plainly  told.  Take  for 
instance  the  section  S.  W.  from  Hardystonville,^  where 
two  gneiss  formations  10'  and  80'  thick  respectively,  and 
about  200'  apart,  are  regularly  interstratified  with  about 
1,000'  of  marble  beds.  One  such  example  would  suffice, 
but  many  others  present  themselves. §  There  can  be  no 

*As  at  Reading,  see  last  loot  note  on  page  103,  above. 

fSee  Report  C4 

{Wood  cut  in  Geol.  N.  J.,  1868,  p.  313. 

§These  alternations  of  gneiss  and  marble  beds  are  finely  exposed  at 
Mine  Hill ;  on  the  Snufftown  road,  southeast  of  Hardystonville  ;  on  the 
Deckertown  road  over  Pochunk  mountain  ;  east  of  that  road  near  Ryer- 
son's ;  and  many  other  places.  The  interstratified  gneiss  beds  appear  in 


THE  ARGUMENT   FROM   MARBLE.  Ill 

more  doubt  of  the  sediment  of  gneiss  in  this  azoic  marble 
formation  than  of  the  sediment  of  St.  Peter's  sandstone  in 
the  magnesian  limestone  of  the  west,  or  of  the  great  sand- 
bed  groups  in  No.  II  throughout  Nittany  valley  in  central 
Pennsylvania,  and  near  Chambersburg  in  Franklin  county. 
It  is  evident  that  the  agents  which  changed  lime  mud  into 
marble,  changed  sand  mud  into  gneiss.  Consequently  the 
great  gneiss  formation  which  contains  in  its  own  body  the 
mnrble  beds,  was  itself  as  a  whole  originally  an'  ordinary 
sand  mud  formation. 

The  marble  beds  vary  greatly  in  crystallization,  texture, 
color,  composition  and  imbedded  minerals ;  generally 
coarsely  (rhombic)  crystalline  ;  sometimes  finely  granular, 
or  even  amorphous  to  the  eye  ;  color  grayish,  pinkish,  but 
generally  pure  white,  with  lustrous  cleavage;  sometimes 
dull,  hard,  siliceous.  Graphite  scales  nearly  everywhere 
disseminated  through  the  mass.  Mica  quite  common. 
Many  other  rare  minerals  occur  in  it. 

Why  is  azoic  marble  so  abundant  in  New  Jersey  and  not 
in  Pennsylvania  ?  A  true  answer  to  this  question  would 
throw  great  light  on  our  gneiss  system. 

It  looks  as  if  a  far  greater  thickness  of  gneiss  comes  to 
the  surface  in  New  Jersey,  and  as  if  the  great  azoic  marble 
formation  must  be  deep  in  the  Pennsylvania  underground. 

Part  of  the  vast  gneiss  system  holds  these  marble  beds, 
and  another  part  does  not.  This  is  evident  from  the  fact 
that  the  first  or  front  range  of  gneiss  Highlands  in  New 
Jersey  only  shows  four  small  outcrops  of  marble.*  The 
second  range  contains  no  known  outcrop  of  marble.  The 
third  range  (and  the  interval  bet  ween  the  second  and  third) 
makes  a  magnificent  display  of  marble  beds  of  great  length 

all  parts  of  the  marble  belt.  Very  frequently  they  are  such  local  deposits 
that  after  running  a  few  yards,  or  a  few  rods,  they  more  or  less  suddenly 
turn  into  limestone.  Some  have  a  length  of  100-200  yards  and  are  from  120 
to  300  feet  in  thickness.  One  at  Ryerson's  is  360'  thick  (or  wide).  Most  of 
the  gneiss  is  a  hornblende  syenite,  without  mica  ;  some  of  it  contains  mica. 
The  trap  dykes  at  Mine  Hill  cross  the  whole  breadth  of  marble  bed,  gneiss 
beds,  sandstone  beds  and  blue  limestone  beds  of  No.  II ;  but  they  are  very 
thin,  only  a  few  inches  wide. 

*Wynokie,  two ;  Montville,  one;  Mendham,  one.  Cook,  Geol.  N.  J.,  p. 
309. 


112  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

and  thickness.*  The  average  width  of  the  marble  belt  is 
one- third  mile,  rarely  exceeds  one- half  mile,  but  across  the 
New  York  state  line  widens  to  two  miles.  But  approach- 
ing Pennsylvania  "the  range  seems  to  thin  out  and  at  last 
disappear  towards  the  southwest."f 

Certainly  there  is  nothing  to  compare  with  this  in  the 
Highlands  west  of  the  Delaware  river.  Now  everything 
combines  to  show  that  our  highland  gneisses  never  rose  to 
as  high  a  level  as  those  of  New  Jersey  ;  and,  if  we  were 
quite  sure  of  the  structure,  we  must  justly  infer  that  our 
gneisses  from  Reading  to  Easton  were  those  of  an  upper 
division  of  the  old  Azoic  ;  a  lower  division  coming  up  to 
the  present  surface  in  New  Jersey  and  New  York,  bringing 
with  it  the  great  marble  formation.  That  would  explain 
things.  But  the  structure  of  the  highlands  is  too  obscure 
to  allow  us  to  rely  on  any  such  generalization.  Therefore, 
we  must  accept  as  a  possibility  that  the  white  limestone 
formation  may  not  have  extended  westward  originally. 
Any  third  hypothesis  that  the  white  marble  beds  are  local 
plutonic  or  volcanic  extrusions  like  outflows  of  lava  cannot 
be  seriously  entertained  now  by  any  one. 

But  a  fourth  source  of  explanation  for  the  small  local 
exhibitions  of  marble  in  gneiss  \  may  be  found  in  the  fact 
of  the  close  plication  of  the  rocks;  the  limestone  being  pre- 
served in  short,  sharp,  collapsed  synclinal  troughs;  or,  as 
in  the  case  of  the  Brandywine  marble  quarry,  projected 
upwards  as  a  sharp-tongued  anticlinal  fold.§  • 

But  in  some  cases  the  white  limestone  is  merely  an  ele- 

*Twenty  miles  long,  from  Mts.  Adam  and  Eve  and  Round  Hill,  in  New 
York,  along  west  side  of  Vernon  valley,  by  Franklin  furnace  to  Sterling 
hill.  No  palaeozoic  rocks  seen.  At  Franklin  the  blue  limestones  of  No.  II 
lap  over  the  marble  beds.  This  state  of  things  keeps  on  through  New  York 
state.  Geol.  N.  J.,  p.  310. 

fProf.  Cook,  G.  of  N.  J.,  p.  312. 

jLike  the  "  detached  outcrops  surrounded  by  gneiss  at  North  Vernon, 
described  by  Prof.  Cook  on  pages  313,  314,  and  a  number  in  Pennsylvania. 
One  of  these  detached  patches  at  North  Vernon,  N.  J.,  seems  to  be  900'  long 
by  600'  wide;  the  other  is  1,700'  long  and  "  quite  narrow;"  a  third  is  5,000' 
long  and  900'  wide,  with  a  good  deal  of  gneiss  included  in  it.  It  seems 
hardly  possible  to  avoid  the  inference  of  complication  and  repetition  in  such 
a  case. 

§See  my  sketch  in  Report  of  Progress  C4,  page  239. 


THE.  ARGUMENT   FROM   APATITE.  113 

ment  in  the  gneiss,  and  what  is  of  more  importance  "  it 
predominates  largely  in  some  of  the  beds  and  enters  some- 
what into  the  composition  of  the  iron  ores  worked"  at  the 
Roseville  mine.* 


The  argument  from  apatite. 

The  Laurentian  age  of  the  highland  gneiss  is  testified  to 
by  the  occurrence  of  regular  apatite  (phosphate  of  lime) 
magnetic  iron  ore  beds  enclosed  in  the  gneiss,  as  in  the 
Adirondack  mountains  of  northern  New  York. 

In  New  Jersey,  in  1871,  at  Ferro-Mont  (Dickerson  M. 
Co.),  a  bed  8'  thick  was  opened,  dipping  65°  S.  E.,  mixed 
magnetite  and  gray-white  apatite,  between  regular  walls  of 
gneiss  in  which  little  if  any  apatite  exists.  Some  parts  of 
the  bed  show  alternate  layers  (or  lenses)  of  magnetite  and 
apatite.  Of  the  whole  mass  50  per  cent  in  bulk  (35  per 
cent  in  weight)  is  apatite,  f  There  is  too  much  phosphorus 
for  the  lime  ;  some  of  it  is  therefore  combined  with  the 
iron.  There  is  a  little  quartz,  feldspar  (orthoclase)  and 
occasional  spangles  of  brown  mica. 


*Cook,  Geol.  of  N.  J.,  page  316.  The  marble  at  Lockwood  is  nearly  pure 
carbonate  lime,  very  coarsely  crystalline,  with  scales  of  graphite  distributed 
through  it,  and  beds  and  horses  of  gneiss  in  it.  Its  whole  length  is  only 
360'  and  its  greatest  width  50'.  The  white  crystalline  limestone  (91  per  cent 
carb.  lime)  along  the  Paulin's  Kill  contains  graphite,  galena,  &c.,  and  in- 
cludes alternating  beds  of  gneiss  (page  317).  The  Andover  white  (some- 
times pinkish)  limestone,  highly  crystalline,  is  so  pure  that  only  traces  of 
magnesia  are  detected  in  it  (page  318).  The  Decker's  Pond  marble  beds 
alternate  with  gneiss  beds  of  the  same  strike  and  dip  (page 318).  But  in  the 
fourth  (Jenny  Jump  or  Oxford)  belt  the  marble  seems  to  be  more  mixed 
with  magnesian  minerals.  It  is  a  great  formation,  with  an  outcrop  4,000' 
wide  but  with  inter  stratified  gneiss  beds.  The  alternation  is  finely  exposed 
at  the  east  end  of  the  20  mil«  outcrop.  The  gneiss  cairies  magnetite  beds,  and 
copper  ore.  The  marble  carries  steatite,  <fec.  The  whole  formation  is  in 
fact  a  dolomite,  and  one  is  tempted  to  think  it  a  metamorphosis  of  No.  II ; 
especially  seeing  that  some  of  its  members  are  flaggy,  flaky  and  finely  crys- 
tallized (pages  319,  320).  This  is  the  Marble  Mountain  outcrop  at  the  Dela- 
ware river. 

fCook,  An.  Rt,  1871,  p.  35.  An  average  specimen  gave  54  of  mag.  iron; 
17.21  lime  ;  14.91  phosphorus  (=»31.90  apatite).  A  picked  piece  gave  53.85apa- 
tite.  The  two  minerals  can  be  separated  by  crushing  and  washing,  or  by 
magnetic  machines.  Soluble  phosphoric  acid  can  be  made,  worth  in  1871 
14  cents  a  pound. 

8 


114  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

In  Berks  county,  Pa.,  apatite  of  a  bluish  color  is  found 
in  very  small  white  hexagonal  crystals  with  the  magnetite 
at  the  Jones'  mine.*  and  at  the  Mt.  Penn  mines. f  But  no 
minable  beds  of  it  have  been  found;  only  scattered  crys- 
tals in  the  gneiss  of  southeastern  Pennsylvania. :{: 

The  original  character  of  the  magnetite  beds  is  indicated 
by  the  fact  that  hydrous  phosphate  of  iron  (cacoxenite) 
are  found  in  the  brown  hematite  (limonite)  iron  ore  mines 
at  Conshohocken,  Montgomery  county  ;  at  Chiques,  Lan- 
caster county;  and  that  minute  quantities  of  phosphoric 
acid  (I  in  the  form  of  cacoxenite)  are  found  in  almost  all 
the  limonite  beds  of  the  state.  Also  the  hydrous  phos- 
phate of  alumina  (wavellUe)  occurs  in  Trimble's  iron  mine 
in  the  Chester  valley,  East  Whiteland;  also  in  concretions  in 
the  York  county  Peach  Bottom  slates  ;  and  at  Chiques  in 
limonite.§ 

It  may  be  objected  that  the  phosphorus  in  limestones  and 
limonites  is  a  derivative  from  that  in  the  gneiss;  or  else 
that  it  comes  directly  from  animal  life- forms  (as  in  the  case 
of  recent  bog-ores);  and,  therefore,  that  it  cannot  indicate 
the  origin  of  the  magnetic  beds.  But  if  other  and  stronger 
arguments  for  the  genesis  of  magnetite  from  brown  hema- 
tite beds  be  at  hand,  then  the  distribution  of  apatite  crys- 
tals and  masses  in  iron-bearing  gneisses  can  be  adduced  as 
an  argument  for  viewing  the  gneisses  themselves  as  sand- 
mud  sediments,  and  their  included  magnetite  beds  as  orig 
inally  bog-ores  or  more  probably  beach  iron  sanfts. 

*D3,  Pt.  2,  page  394. 

t Rogers'  Geol.  Pa.,  1858,  II,  page  716. 

jGenth,  Report  B,  page  138.  Blue  green  hex.  prisms  at  McKinney's 
quarry  near  Gennantown,  in  massive  orthoclase;  at  Megargee's  paper  mill; 
atFrankford;  at  Grey's  ferry  and  West  Philadelphia;  at  Leipersville  and 
at  Beattie's  mill,  Delaware  county;  at  Unionville,  Chester  county.  Fine 
yellow-green  hex.  prisms  and  conchoidal  masses  in  Londongrove  township, 
Chester  county;  in  the  limestone  of  .Bernard's  quarry,  West  Marlboro';  at 
Nivin's  limestone  quarry  in  North  Garden.  Bluish  hex.  prisms  and  grains 
and  masses  in  Van  Arsdale's  limestone  quarries,  southern  Bucks  county. 
Straw  and  honey  colored  hex.  prisms,  with  pyramid  and  basal  plates,  with 
crystallized  dolomite,  in  Prince's  soapstone  quarries,  Lafayette,  Montgom- 
ery county. 

§Genth,  B,  144. 


THE  ARGUMENT  FROM  IRON  ORE.          115 


The  argument  from  iron  ore. 

The  great  beds  of  magnetic  iron  ore  in  the  Highlands 
show  unmistakable  evidences  of  sedimentary  origin;  there- 
fore, the  gneisses  in  which  they  lie,  and  into  which  they 
graduate  by  insensible  stages,  must  be  of  sedimentary 
origin.  That  is  the  plain  and  simple  argument. 

In  New  Jersey,  boring  for  magnetic  iron  ore  is  recom- 
mended by  Prof.  Cook  on  the  supposition  that  the  beds 
are  practically  continuous  down  the  dip  as  along  the  strike, 
which  is  undoubtedly  judicious.  He  assigns  a  useful  limit 
of  2,000'  in  depth,  in  view  of  the  expenses  of  hoisting.  In 
our  ignorance  of  the  depth  underground  he  well  says  that 
"a  single  boring  might  develop  the  existence  of  more  ore 
than  is  mined  in  the  whole  state  in  the  course  of  a  year."* 

The  replacement  of  ore  by  rock,  and  the  alternation  of 
bands  of  magnetite  and  gneiss  are  well  shown  by  Cook  in 
his  report  of  1873,  pages  78  to  87.  The  ore  is  never  in 
veins  cutting  the  gneiss,  but  always"  in  interstratified  beds 
following  the  strike;  report  of  1874,  page  34.  The  alternate 
banded  structure  is  shown  by  Cook  in  the  report  of  1874, 
page  23;  and  again  at  the  Ten  Eyck  mine  in  the  report  of 
1876,  page  52. 

The  hanging  wall  ore  is  clean  ;  the  foot  wall  ore  is  mixed 
with  feldspar,  quartz  and  hornblende.  As  in  the  case  of 
the  apatite  mines  of  northern  New  York,  so  here,  were  the 
ore  a  solidified  fluid  filling  a  fissure  the  pure  ore  would  not 
occupy  one  side  and  the  impure  ore  the  other,  but  the  pure 
ore  would  be  in  the  deep  filling  the  whole  chasm,  and  the 
impure  ore  would  have  occupied  the  whole  chasm  above  it, 
as  the  cinder  floats  on  the  metal  in  an  iron  furnace.  In  the 
case  of  the  Adirondack  mines  the  apatite  occupies  the 
hanging  wall  part  of  the  vein  ;  but  in  the  New  Jersey  High- 
land mine  the  impurities  occupy  the  foot-wall  portion  of  the 
vein.  This  signal  distinction  points  still  more  strongly  to 
original  sedimentation. 

The  connection  of  the  New  Jersey  magnetite  beds  with 

*An.  Rt,  1872,  pages  24,  26. 


116  GEOLOGICAL   SURVEY    OF   PENNSYLVANIA. 

white  chrystalline  limestone,  or  marble,  tells  the  same  story 
in  another  form. 

The  Schuler  ore  pits,  near  Roxburg,  in  the  Pequest  belt 
of  N.  J.,  show  tine-grained  magnetite  (with  much  man- 
ganese) in  grey -white  crystalline  limestone,  steep  to  S.  E.* 

The  Roseberry  ore,  near  Belvidere,  is  mixed  with  much 
mica  and  blue  shaley  rock. 

The  Barton  black  granular  ore  has  a  little  hornblende  and 
much  dark  micaceous  gneiss. 

The  Shoemaker  ore  is  a  rock  containing  magnetite  ar- 
ranged in  parallel  lines  with  the  usual  gneissic  minerals,  f 

The  Redell  ore  is  black  manganiferous  magnetite,  non- 
sulphurous,  in  contact  with  gray  crystalline  limestone. 

The  Raub  ore,  N.  W.  of  Oxford  furnace,  lies  close  to  the 
crystalline  limestone,  if  not  in  it.$ 

The  magnetite  vein  at  the  Kanouse  mine  has  close  to  it  a 
crystalline  limestone  containing  a  large  percentage  of  ser- 
pentine, and  in  contact  with  this  (conformably)  a  grey 
gneiss.  (Cook,  An.  Rt.  N.  J.,  1873,  p.  28  V.) 

The  Marble  mountain  part  of  the  Pequest  belt  of  iron 
ores  in  IS".  J.  is  the  most  northerly,  next  the  Great  Valley 
limestone  formation,  and  its  ores  differ  from  those  of  the 
other  Highland  belts.  The. belt  is  a  continuation  of  that  in 
Pennsylvania,  and  is  therefore  instructive  for  our  geology. 

The  Marble  mountain  mine  is  especially  interesting  for 
the  fact  that  the  ore  is  red  hematite  in  a  talcose  (mag- 
nesian)  formation,  included  in  or  resting  on  gneiss,  uncon- 
formably:§  This  talcose  slate  occurs  in  this  Pequest  belt 
only  and  in  no  other  in  N.  J. 

The  Titman  shaft  ore,  S.  E.  of  Bridgeville,  is  red  hema- 
tite, in  a  grayish  red  slate  formation,  lying  between  mica- 
ceous and  hornblendic  gneiss  on  the  south  and  common 
blue  magnesian  limestone  on  the  north,  and  "probably  non- 
•conformable  to  both.|| 

*Cook,  An.  Rt.  1873,  p.  73. 
fCook,  An.  Rt  1873,  p.  74. 
jCook,  An.  Rt.  1873,  p.  75,  76. 
§Cook,  An.  Rt.  1873,  p.  72. 
J|P.  76. 


THE  ARGUMENT  FROM  IRON  ORE.          117 

The  Welsh  and  Inschow's  lean  manganiferous  magnetite 
is  imbedded  in  grey  white  crystalline  limestone  (steep  to 
N.  W.)  holding  hornblende,  a  little  mica,  and  much 
graphite,  and  some  manganese.  In  one  hole  the  ore  was  in 
thin  strings  through  the  limestone,  which  itself  held  brown 
garnet  and  serpentine.* 

The  Howell  farm  ore  (10'wide)  includes  impure  limestone, 
but  lies  in  or  against  a  hard  gray  close  gneiss  country. 
Near  by  the  ore  holds  much  calcite  and  graphite,  f 

*Cook's  An.  Rt  1873,  p.  84. 
fCook's  An.  Rt  1873,  p.  86. 


118  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 


CHAPTER  XI. 
The  Newer  Gneiss  of  the  Philadelphia  Belt. 

The  Schuylkill  river,  after  cutting  through  the  Older 
gneiss  of  the  Buck  ridge  already  described,  makes  a  pic- 
turesque narrow  valley,  bounded  by  low  bluffs  of  newer 
gneiss  and  mica  schists  as  far  down  as  the  Gray's  Ferry 
bridge,  in  the  south  part  of  Philadelphia. 

These  rocks  belong  to  one  system  and  one  age  and  have 
a  general  moderate  dip  toward  the  north-northwest.  So 
that,  if  no  reduction  need  be  made  for  irregularities  or  repe- 
titions, there  must  be  visibly  exposed  along  the  river 
banks  more  than  20,000  feet  of  strata.  But  they  have  been 
subject  to  great  pressure,  as  is  shown  by  myriads  of  con- 
tortions, by  a  perpetual  variation  of  local  strike  and  dip, 
and  by  small  faults,  how  many  or  how  important  it  is  dif- 
ficult to  determine  with  any  accuracy.  There  may  there- 
fore be  in  reality  no  more  than  15,000  feet,  or  even  less. 

Still,  the  mass  is  evidently  so  great,  and  in  a  large  sense 
so  regularly  and  conformably  stratified  from  the  visible  tog 
of  it  at  Lafayette  station,  to  the  lowest  visible  beds  at  Gray's 
ferry,  that  the  Lafayette  station  beds  must  have  once  risen 
southward  into  the  air  to  a  height  of  10,000  or  15,000  feet 
above  the  present  street  grade  of  Philadelphia.  In  other 
words,  a  mountain  range  of  that  height  once  extended  from 
Trenton,  New  Jersey,  past  Philadelphia,  Baltimore  and 
Washington  into  the  southern  states. 

This  mountain  range  has  been  gradually  washed- away. 
The  length  of  time  requisite  to  accomplish  such  destruction, 
slow  as  it  must  have  been,  is  inconceivably  great,  a  fact  suf- 
ficient of  itself  to  prove  that  we  are  dealing  with  one  of  the 
oldest  geological  rock  systems  of  the  world. 

The  mountain  range,  when  at  its  full  height,  must  have 
presented  cliffs  of  great  height  and  steepness  towards  the 


THE   NEWER   GNEISS   OF  THE   PHILADELPHIA   BELL.     119 

Atlantic;  cliffs  representing  the  basset  edges  of  all  the 
strata  which  we  now  see  in  succession  along  the  river 
from  Lafayette  station  down  to  Gray's  ferry.  There  is  no 
arch  visible,  and  no  evidence  that  the  strata,  after  rising  to 
the  full  height,  turned  over  and  descended  with  an  opposite 
dip.  For,  if  that  had  happened,  southern  New  Jersey 
would  have  now  a  geological  character  similar  to  that  of  the 
Philadelphia  belt,  and  the  Delaware  river  would  not  have 
established  its  channel  on  a  course  directly  in  front  of  and 
across  the  mouth  of  the  valley  of  the  Schuylkill. 

All  geologists  would  agree  in  the  belief  that  the  line  of 
the  Delaware  from  Trenton  to  Chester  must  be  the  line  of 
one  of  the  greatest  downthrow*  faults  which  the  earth- 
crust  has  suffered  ;  and  that  the  whole  series  of  strata  seen 
along  the  Schuylkill  exists  now  at  a  great  depth  under- 
ground beneath  the  Cretaceous  and  Tertiary  plains  of  New 
Jersey,  southern  Delaware  and  eastern  Maryland.  In  east- 
ern Virginia  and  the  Carolinas  they  spread  out  at  the  sur- 
face. In  the  opposite  direction  they  underlie  middle  New 
Jersey  and  appear  again  at  the  surface  at  New  York.  Our 
Germantown  hills  are  the  hills  of  Staten  and  Manhattan 
Islands  ;  and  the  whole  formation  continues  broadening  and 
rising  east  of  the  Hudson,  through  western  Massachusetts 
and  Vermont,  where  it  constitutes  part  of  the  great  Green 
mountain  range. 

The  bottom  of  this  system  of  rocks  is  unknown,  because 
concealed  beneath  the  Delaware  valley  muds  and  the  New 
Jersey  green  sand  marl  formation.  The  lowest  beds  visible 
are  those  at  Gray' s  ferry.  They  are  very  f eldspathic  schists, 
in  a  state  of  complete  decay,  being  turned  into  a  coarse 
sort  of  porcelain  clay  or  kaolin.  From  these  Gray's  ferry 
beds  upward  the  series  may  be  examined  along  both  banks 
of  the  Schuylkill  river,  in  the  cliffs  of  Fairmount,  in  the 
cuttings  of  the  Pennsylvania  R.  R.  on  the  west  bank,  in 
those  of  the  Reading  R.  R.  on  the  east  bank,  in  the  road 

*It  would  be  more  historically  true  to  speak  of  it  as  an  upthrow.  For  it  is 
quite  possible  that  the  movement  upward  which  evidently  took  place  on  the 
north  side  was  not  accompanied  or  balanced  by  a  downward  movement  of 
equal  value  on  the  south  side  of  the  fault 


120  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

cuttings  of  the  city  park  at  Manayunk,  at  the  quarries  on 
Wissahickon  creek,  and  along  the  drive-ways  to  German- 
town  and  Chestnut  Hill.  No  better  exposures  of  a  great 
rock  sytem  can  be  found  anywhere. 

Its  three  sub-divisions. 

The  lower,  middle  and  upper  rocks  exposed  along  the 
Schuylkill  differ  in  general  character  sufficiently  to  justify 
three  sub-divisions  of  the  system,  named  by  Mr.  C.  E.  Hall 
in  his  report  C6 : — (1)  The  lower,  or  Philadelphia  mica 
schist  and  gneiss  group;  (2)  The  middle,  or  Manayunk 
mica  schist  and  gneiss  group  ;  (3)  The  upper,  or  Chestnut 
Hill  garnetiferous  schist  group. 

The  course  of  the  river  Schuylkill  in  its  traverse  of  the 
whole  belt  is  worthy  of  careful  study. 

From  Spring  Mill  to  the  Falls  of  Schuylkill,  6|  miles,  its 
course  is  almost  a  perfect  straight  line,  square  across  the 
strike,  i.  e.,  S.  45°  E.  In  this  distance  it  first  cuts  through 
the  Old  (Laurentian  Buck  ridge)  gneiss,  one  mile  ;  then  the 
Chestnut  Hill  group,  1£  miles  ;  then  the  Manayunk  group, 
3£  miles,  and  then  half  a  mile  through  the  upper  beds  of 
the  Philadelphia  group.* 

At  the  Reading  railroad  bridge  (Falls  of  Schuylkill)  the 
Schuylkill  makes  a  right-angle  bend  to  the  right  and  cuts 
nearly  along  the  strike,  about  S.  40°  W.  H  miles  to  the 
Columbia  bridge,  f 

Then  it  makes  a  right-angle  bend  to  the  left  and  cuts 

*The  Wissahickon,  the  Schuylkill  and  the  Brandywine  all  flow  from  the 
low  limestone  Chester  county  valley  into  and  through  gneiss  gorges  on 
their  way  to  the  Delaware.  In  the  case  of  the  Wissahiccon  the  act  is  start- 
lingly  bold,  because  accomplished  by  a  small  stream.  But  all  the  rivers  of 
he  state  do  the  same  deed  repeatedly.  How  do  they  do  it  ?  The  question 
presents  itself  in  view  of  every  mountain  gap  in  the  state.  It  will  be  dis- 
cussed further  on  in  this  report ;  but  it  may  be  said  here  that  when  the 
gorges  of  the  Schuylkill,  Wissahiccon  and  Brandywine  were  made  the 
Chester  valley  was  at  much  higher  level.  Its  lime  rocks  have  been  dis- 
solved faster  than  the  gneiss  and  its  level  lowered  more  rapidly. 

fThis  part  of  the  valley  corresponds  to  the  low  ground  which  runs  for 
miles  at  the  foot  of  and  in  front  of  the  Txermantown  hills,  past  Nicetown 
and  the  brickyards.  At  the  Columbia  bridge  the  river  makes  a  bend  around 
the  west  foot  of  the  hill  on  which  the  East  Park  reservoir  is  placed. 


THE   PHILADELPHIA  (LOWEB)  SUB-DIVISION.  121 

nearly  straight  across  the  strike,  S.  80°  E.  2£  miles,  along 
the  dam  and  past  Fairmount  to  Vine  street. 

Here  it  swings  round  again  to  the  right  past  the  Market 
street  bridge,  and  follows  the  strike  1|  miles  S.  W.  to 
Gray's  Ferry — after  which  its  meanders  to  the  Delaware  are 
in  river  muds  and  have  no  regard  for  the  underlying  rocks.* 

Had  the  Schuylkill  prolonged  its  upper  straight  course 
across  the  strike  four  miles  further  to  the  last  gneiss  struck 
in  the  cellars  of  Kensington,  at  the  edge  of  the  river  mud, 
and  made  its  mouth  at  the  bend  of  the  Delaware  below  Port 
Richmond,  we  should  have  had  9£  miles  of  continuous  ex- 
posures across  the  whole  Philadelphia  belt,  say  50,000  feet 
in  breadth,  dipping  practically  all  one  way,  at  angles  never 
less  than  20°,  often  over  50°,  and  in  places  vertical.  In 
spite  of  all  disturbances  of  the  dip  it  is  not  an  unsafe  esti- 
mate then  which  assigns  to  the  whole  system  a  thickness  of 
20,000  feet.f 

1.   Tlie  PJtiladelpJiia  (lower]  sub-division. 

The  Philadelphia  rocks  show  themselves  from  Grey's 
ferry  up  to  the  mouth  of  the  Wissahickon.  The  slope  of 
the  strata  is  always  up  river,  but  with  many  contortions  to 
the  right  and  left,  sometimes  through  a  quadrant  of  the 
compass.  In  the  steep  wall  of  Fairmount,  under  the  old 
reservoir,  the  dip  varies  between  20°  and  40°.  On  the  rail- 
road opposite  it  is  generally  about  20°.  Further  on  through 
the  park  it  often  rises  to  50°  and  60°.  At  the  foot  of  Lemon 
hill  the  most  curious  and  beautiful  wavings  and  foldings 
may  be  seen  in  the  much-weathered  and  mouldered  mica 
schists,  marked  by  thin  streaks  of  milky  quartz,  which  has 
been  deposited  as  a  gelatinous  solution  in  seams  where  the 
twisted  beds  moved  on  one  another  and  were  slightly  parted 
here  and  there.  The  whole  soil  glitters  with  shining  little 
flakes  of  brown  and  yellow  mica,  set  free  from  the  mould- 

*It  is  possible  that  the  course  from  Market  street  to  Gray's  Ferry  was  de- 
termined by  some  past  condition  of  the  terrace  gravel  deposits.  But  that  is 
not  likely  in  view  of  the  fact  that  it  here  repeats  its  conduct  between  the 
Falls  of  Schuylkill  and  the  Columbia  bridge. 

fWe  shall  see  in  the  next  chapter  that  the  same  system  (probably)  on  the 
Susquehanna,  in  York  county,  shows  a  similar  thickness. 


122  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

ering  rock.  Very  few  solid  beds  can  be  found,  and  the 
surface  stone  is  worthless.  Even  where  quarries  have  been 
opened  the  undecayed  stone  can  only  be  used  for  the 
roughest  building  purposes,  although  all  cellar  walls  in  the 
older  and  much  of  the  newer  parts  of  Philadelphia  have 
been  built  of  the  grey  micaceous  gneiss.  Railroad  cuttings 
through  tough  and  apparently  enduring  rock  become  in  a 
few  years  mere  ditches,  with  softened  sides  covered  with  the 
micaceous  clay  into  which  the  rock  is  converted  by  the 
weather.  This  accounts  for  the  lowness  of  the  hills  on  both 
sides  of  the  river;  and,  in  fact,  for  the  disappearance  of  the 
great  mountain  range  which  once  occupied  the  Philadel- 
phia belt  country. 

But  among  the  grey  micaceous  gneiss  beds  and  mica  slate 
beds  occur  numerous  beds  of  hard  hornblende-gneiss,  which 
is  a  good  quarry  stone  and  stands  well.  There  are  places 
where  the  dark  hornblende-gneiss  beds  and  the  light-grey 
mica-gneiss  beds  are  interleaved  and  alternate  regularly, 
showing  that  the  hornblende-gneiss  is  a  true  sedimentary 
rock  and  not  in  any  sense  volcanic. 

Mr.  Hall's  description  of  the  rocks  of  this  group  (H.  D. 
Rogers'  "first  belt")  is  as  follows  :  "The  common  varieties 
are  grey  schistose'gneiss,  composed  of  quartz,  feldspar,  and 
black  or  brown  mica,  and  occasionally  garnets,  occasional 
beds  of  black  hornblende  slate,  and  fine-grained  sandy 
gneiss."  (C6,  page  2). 

#.  The  ManayunJc  (middle)  sub-division. 

The  exposures  extend  from  the  mouth  of  the  Wissa- 
hickon  up  to  the  mouth  of  Mill  creek,  three  miles.  But. 
neither  the  one  limit  nor  the  other  is  well  defined.  The 
separation  of  this  group  from  that  beneath  it  and  that  above 
it  is  rather  arbitrary.  Its  gneisses  are,  however,  chiefly 
micaceous  ;  fewer  hornblende  gneiss  beds  are  seen.  Yet 
the  weathered  surfaces  and  the  soils  resulting  from  the  de- 
composition of  the  outcrops  have  a  darker  color  than  the 
surfaces  and  soils  of  the  Philadelphia  rocks,  a  dark  iron- 
rust  yellow,  or  brown,  especially  where  the  hornblende 
slates  run. 


THE  MANAYUNK   OK   MIDDLE   SUB-DIVISION.  123 

The  dip  is  still  generally  northwest  up-river,  but  with 
numerous  waves  and  folds  in  the  bluffs  and  the  railroad 
cuts.  One  arch  of  considerable  size  may  be  seen  in  the  Mc- 
Kinney  quarry  on  the  south  side  of  the  Wissahickon  at  the 
ascent  of  G-ermantown.*  Here  also  the  excellent  quality  of 
the  better  varieties  of  gneiss  is  practically  displayed.  On 
the  north  side  of  the  creek  at  its  mouth  the  convolutions 
and  sharp  foldings  of  the  schists  plainly  reveal  both  the 
'mashing  and  the  stretching  pressure-strains  to  which  they 
have  been  subjected. f 

Mr.  Hall's  description  of  the  Manayunk  group,  which  he 
interpolated  between  H.  D.  Rogers'  "first"  and  "second 
belts,"  is  as  follows:  ''Alternations  of  the  above-named 
varieties  of  gneiss  (named  in  the  Philadelphia  group)  and  a 
predominance  of  sandy  gneiss,  composed  of  quartz  and  a 
small  amount  of  feldspar  and  mica  in  minute  flakes.  Mica 
schists  and  hornblendic  slates  alternate  with  finer-grained 
gneisses,  the  mica  usually  light-colored  "  (C6,  page  2). 

3.   The  Chestnut  Hill  (upper}  sub-division. 

The  exposures  extend  from  the  mouth  of  Mill  creek  for 
half  a  mile  up  to  the  Lafayette  soapstone  quarries  with  a 
constant  general  northwest  dip,  and  these  continue  for  an- 
other half  mile  to  a  serpentine  outcrop  along  the  south 
edge  of  the  Bear  Ridge  older  gneiss  belt,  but  with  reversed 
(S.  E.)  dips.  Therefore,  there  is  here  a  synclinal  basin,  and 
then  a  great  fault,  in  'which  must  be  buried  (against  the 
older  gneiss  mass)  the  Manayunk  and  Philadelphia  sub-di- 
visions.^: 

The  dips,  both  north  and  south,  are  however  very  steep 

*This  quarry  is  extensively  worked  for  city  use  and  is  famous  for  its 
specimen  crystals  of  hornblende,  orthoclase  feldspar,  chrysocolla,  mala- 
chite, bornite,  chalcopyrite,  heulandite,  apatite,  etc.  The  presence  of  these 
copper  and  phosphorus  minerals  is  noteworthy. 

f  A  fine  exposure  of  a  double  or  S  fold  along  the  north  Pennsylvania  R.  R. 
above  Shoemakerstown,  is  represented  in  Mr.  Hall's  section  in  Report  C6, 
page  2&  The  minor  complications  under  the  fold  show  how  the  schists 
slid  upon  each  other  with  a  certain  difficulty  and  much  friction. 

JAt  least  this  is  the  best  explanation  of  the  structure  which  has  been  ob- 
tained. 


124  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

and  often  quite  vertical ;  and  the  strata  are  even  more  con- 
torted than  elsewhere  along  the  Schnylkill. 

The  characteristic  featiires  of  the  group  are  its  mica 
schists  crowded  with  garnets,  its  thin-bedded  sandy 
gneisses,  its  hornblendic  slates,  and  its  two  ranges  of  ser 
pentine  beds.  * 

The  Lafayette  steatite  or  soapstone  quarry  has  been 
wrought  for  a  century  and  is  now  regularly  mined  in  gal- 
leries. The  rock  dips  steeply  northwest. f  It  is  part  of  a 
line  of  serpentine  outcrops  which  extends  at  least  seven 
miles  in  an  almost  straight  (but  not  continuous)  line  from 
Bryn  Mawr  N.  E.  to  Chestnut  Hill,  crossing  the  Schuylkill 
at  the  soapstone  quarry,  and  the  Wissahickon  a  quarter  of 
a  mile  below  the  gorge  of  older  gneiss,  where  it  is  well-ex 
posed  on  the  road  up  to  the  village  of  Chestnut  Hill 4 

Another  line  of  serpentine  outcrops  crosses  the  river  half 
a  mile  above  the  soapstone  quarry  ;  is  traceable  only  half  a 
mile  east  of  the  river;  but  west  at  intervals  into  Delaware 

*Mr.  Hall  says  in  another  place  "this  second  belt"  of  Prof.  Rogers'  (that 
part  of  it  not  included  in  my  inserted  Manayunk  belt)  is  characterized  by 
the  serpentines;  soapstone;  silvery  micaceous,  garnetiferous  schists;  light- 
colored,  thin  bedded  sandy  gneiss,  with  disseminated  light-colored  mica  in 
minute  flakes ;"  and  a  very  curious  peculiarity  of  fracture,  "the  rock 
breaking  into  long  narrow  chunks,  comparatively  smooth  on  their  sides, 
but  excessively  ragged  on  their  ends;  a  style  of  fracture  strongly  resemb- 
ling that  of  half-rotted  fibrous  wood."  (Quoted  from  H.  D.  Rogers'  Geol. 
Pa.,  by  Hall,  in  C6,  page  2.) 

As  for  Rogers'  "third  belt,"  it  is  the  Bunk  ridge  Older  gneiss.  Hall 
traced  it  in  a  straight  line  to  the  Delaware  river  and  found  it  everywhere 
overlaid  on  both  sides  by  the  quartzite  ("Primal,"  "Potsdam,"  "Itacobu- 
mite,"  "Eurite")  beds,  which,  east  of  Willow  Grove,  Moreland  township, 
Montgomery  county,  are  a  coarse  sandstone  and  conglomerate,  holding 
fragments  of  the  older  gneiss,  principally  the  characteristic  blue  quartz  and 
syenite.  (  C6,  page  3. ) 

fThe  soapstone  quarry  is  about  100  feet  wide,  with  walls  nearly  as  high, 
and  so  dangerous  that  tunnel  work  has  been  substituted.  Thousands  of  tons 
loosened  by  the  decomposition  of  the  magnesian  substance  fell  with  a  great 
crash  when  the  Pennsylvania  railroad  company  cut  their  new  valley  branch 
across  one  end  of  the  quarry.  The  tunnel  work  is  about  filteen  feet  wide 
and  as  many  high.  A  few  hundred  yards  above  the  quarry  a  road  ascends 
to  Roxbury  by  a  hollow  in  the  woods  called  Rockdale,  from  the  great  num- 
ber of  loose  rock  masses  scattered  and  grouped  about,  some  as  large  as 
houses. 

JSee  Hall's  large  colored  map  on  the  scale  of  5,000'-1"  in  C6,  and  text  page 
92.  Also  T.  D.  Rand's  sketch  map  in  Ann.  Rept.  1886. 


THE   CHESTNUT   HILL   OR   UPPER   SUB-DIVISION.  125 

county.  This  line  of  serpentine  seems  to  outline  the  contact 
of  the  newer  and  older  gneiss.  If  the  other  serpentine  belt 
be  in  the  axis  of  a  synclinal,  this  one  must  be  at  least  2,000 
feet  lower  in  the  series,  i.  e.,  supposing  both  to  be  bedded 
and  not  volcanic  rocks.* 

The  Chestnut,  Hill  fault. 

The  extension  of  the  Lafayette  serpentine  belt  eastward 
far  beyond  the  other  to  the  north  of  it  gives  the  key  to  the 
whole  structure  of  the  Philadelphia  belt  between  the 
Schuylkill  and  the  Delaware  at  Trenton. 

All  three  sub-divisions  are  sliced  off  diagonally  by  a 
fault. 

The  Chestnut  Hill  group,  whether  synclinal  or  monoclinal, 
ends  in  a  point  at  Jenkintown,  8  miles  east  of  the  Schuyl- 
kill. The  Manayunk  group  fines  away  to  nothing  between 
the  Pennypack  and  Pequessing  creeks,  seven  or  eight  miles 
east  of  Jenkintown.  The  Philadelphia  group  narrows  more 
and  more,  but  reaches  the  Delaware  at  Easton. 

In  fact  there  is  not  a  more  remarkable  feature  of  the 
geology  of  Pennsylvania  than  the  thirty  mile  Jong  per- 
fectly straight  line  of  the  Itacolumite  (Eurite}  vertical  beds 
which  extends  from  the  Wissahickon  to  the  Delaware,  and 
against  which  the  various  members  of  the  Philadelphia, 
Manayunk  and  Chestnut  Hill  schists  one  after  the  other  ef- 
face themselves.  If  this  be  riot  a  great  diagonal  fault, 
then  all  common  proofs  of  such  a  fault  may  well  be  set 
aside. t  But  it  becomes  of  still  greater  importance  when 
taken  in  connection  with  the  jifty-mile  long  straight  line 
of  vertical  uplift  of  the  South  Valley  hill  between  the 
Schuylkill  and  the  middle  of  Lancaster  county.  Straight' 
geological  lines  are  a  great  rarity.  Curves  are  the  rule.  A 
straight  line  eighty  miles  long  must  mean  something  great. 
It  deals  with  huge  thicknesses  of  formations,  and  with  im- 

*The  steatite  is  probably  an  altered  schist  bed,  for  specimens  can  be  found 
showing  stages  of  the  alteration,  and  the  hanging  wall  rock  contains  crys- 
tals of  staurolite  altered  into  serpentine. 

fM.  Renevier's  recent  protest  against  such  faults  and  advocacy  of  trans- 
verse deposition  in  the  rocks  of  Canton  Valais,  however  well  sustained  at 
La  Tini6re,  can  have  no  force  here. 


126  GEOLOGICAL   SURVEY    OF   PENNSYLVANIA. 

mense  depths  beneath  the  surface.  In  the  azoic  rocks  they 
mean  dislocations,  down  or  upthrow  faults.  In  the  palaeo- 
zoic rocks  they  mean  anticlinal  and  synclinal  folds  of  a 
massive  amplitude  that  take  away  the  breath  of  the  spec- 
tator.* 

Look  at  the  folds  in  a  lady's  thin  silk  dress,  then  at  the 
folds  in  a  heavy  cotton  shirt,  then  at  the  folds  in  a  woolen 
winter  cloak.  See  how  the  system  of  innumerable  delicate, 
short  and  irregular  crimples  of  the  first  passes  into  a 
system  of  long,  straight  solemn  lines  in  the  last.  The  sedi- 
ments of  time  are  the  dresses  of  the  planet,  and  their  com- 
plications imitate  the  draperies  of  statuary.  Therefore,  the 
strikes  of  the  rocks  are  sure  indications  of  both  quality 
and  quantity  of  formations.  If  we  had  no  other  proof  of 
the  immense  thickness  of  the  Philadelphia  gneiss  and  mica 
scbist  system,  this  vertically  erect  and  perfectly  straight 
long  itacolumite  outcrop  would  be~alone  sufficient ;  just  as 
the  forty-mile  straight  line  of  the  Bald  Eagle  mountain  in 
Lycoming,  Centre  and  Clinton  counties  is  sufficient  proof 
that  the  great  fold  of  Nittany  valley  deals  with  40,000  feet  of 
sediments  as  an  integral  mass,  one  and  entire. 

*For  example,  the  synclinal  of  Pottsville  and  the  anticlinal  of  the  Orwigs- 
burg  valley  in  Schuylkill  county. 


THE   PHILADELPHIA   BELT   WESTWARD.  127 


CHAPTER  XII. 

The  Philadelphia  rocks  in  Chester,  Lancaster  and  York 
counties. 

The  structural  obscurity  of  the  azoic  rocks  of  the  region 
bordering  the  state  line  between  the  Schuylkill  and  the  Sus- 
quehanna  cannot  be  exaggerated.  If  the  colored  state  map 
published  by  H.  D.  Rogers  in  1858  be  compared  with  C.  E. 
Hall's  colored  county  map  of  Delaware  (1884),  andFrazer's 
maps  of  Lancaster  and  Chester  (1878,  1881),  it  will  be  seen 
how  unsatisfactory  is  our  knowledge  of  a  district  on  which 
three  independent  geologists  of  great  experience  lavished 
years  of  patient  field  work,  only  to  arrive  at  contradictory 
conclusions  respecting  the  relationships  of  some  of  its 
large  formations  to  one  another,  while  they  agree  singularly 
well  in  their  special  observations  of  local  facts,  which,  after 
all,  are  the  only  things  of  value  to  the  public. 

It  is  a  region  of  excessive-pressure  disturbance.  Thou- 
sands of  smaller  rolls,  and  some  great  waves,  traverse  it 
from  east  to  west.  Its  outcrops  of  gneiss,  mica  schist, 
hornblende  schist,  argillite,  quartzite,  serpentine  and  lime- 
stone dip  at  all  angles  and  in  both  directions.  The  crump- 
ling is  complete.  The  alternations  are  infinite.  Crystalli- 
zation and  metamorphosis  have  not  only  destroyed  every 
trace  of  fossil  life  forms  (if  any  there  were  originally),  but 
changed  the  characteristic  qualities  of  the  rock  itself.  Sec- 
ondary minerals  have  been  produced  abundantly.  Groups 
of  strata  are  inverted,  the  older  upon  the  newer.  Faults  in- 
terrupt the  run  of  the  outcrops. 

All  this  has  been  brought  about  by  the  general  earth 
movement  northwestward  which  produced  the  huge  anti- 
clinal and  synclinal  rock- waves  of  middle  Pennsylvania. 
Measured  by 'straightening  out  these  waves  the  thrust  from 
the  southeast  has  shoved  the  country  at  least  forty  miles 


128  GEOLOGICAL   SURVEY   OF    PENNSYLVANIA. 

towards  the  Allegheny  mountain,  crumpling  its  stratifica- 
tion into  this  labyrinth  of  confusion  and  altering  its  lithol- 
ogy  so  as  to  deprive  the  observer  of  a  clew  through  it. 

If  the  distinction  between  the  Older  and  the  Newer  Gneiss 
be  a  valid  one,  the  Older  gneiss  seems  to  disappear  from 
the  surface  going  west  from  the  Schuylkill  into  Chester 
county,  and  the  Newer  gneiss  seems  to  occupy  the  whole 
field  south  of  the  belt  of  South  Valley  Hill  hydro-mica 
slate*  in  Chester,  and  south  of  the  great  limestone  plain  of 
Lancaster  county.  Dr.  Frazer  assumes  that  it  occupies  his 
broad  Tocquan  belt  in  York  county.  His  sections  along 
the  Susquehanna  river  are  therefore  of  the  greatest  import- 
ance for  comparison  with  the  Schuylkill  river  section.  It 
can  hardly  be  doubted  that  the  grey  gneisses,  mica  schists, 
etc.  of  southern  York  are  the  same  as  those  of  Philadel- 
phia, Manayunk  and  Chestnut  Hill,  although  no  such  sub- 
division as  Hall's  has  been  made  of  them.f 

I  will  therefore  summarize  Dr.  Frazer' s  descriptions  of 
the  azoic  formations  in  York  county  before  attempting  any 
concordance  of  them  with  the  Philadelphia  rocks,  or  any 
identification  of  them  across  the  intervening  counties. 

The  Newer  Gneiss  in  York  county. 

The  belt  of  azoic  schists  across  which  the  Susquehanna 
river  flows,  between  Lancaster  and  York  coilnties,  is  about 
15  miles  wide  at  the  river,  which  enters  the  belt  at  Turkey 
Hill  and  leaves  it  at  Muddy  creek.  Low  hillsides  along  the 
river,  with  natural  outcrops  and  railroad  cuttings,  show  the 
structure  of  the  belt  to  be  that  of  a  broad  fiat  anticlinal  arch, 
its  axis  crossing  the  river  at  the  mouth  of  Tocquan  creek 
(McCall's  ferry).-  There  the  lowest  strata  appear,  the 
highest  being  of  course  at  the  north  and  south  edges  of  the 
belt, 

*Nothing  has  as  yet  been  said  in  this  summary  report  about  the  hydro- 
mica  slate  belt,  although  it  appears  on  the  Schuylkill  river  opposite  Con- 
shohocken  and  ranges  through  Chester  into  Lancaster  county,  because  it 
can  best  be  studied  on  the  Susquehanna  and  in  York  county,  and  in  Mary- 
land. 

fMr.  Hall,  in  coloring  his  Delaware  county  map,  abandoned  the  attempt 
to  represent  the  distinction  between  the  Philadelphia  and  Manayunk 
grc  ups. 


THE   NEWER   GXEISS   IN   YORK   COUNTY.  129 

Dr.  Frazer's  sections  along  both  banks  of  the  river,  show- 
ing north  dips  up  river  and  south  dips  down  river,  gave  him 
a  closely-estimated  total  exposed  thickness  of  more  than 
fourteen  thousand  (14,400)  feet.*  How  much  more  should 
be  added  for  the  oldest  members  of  the  formation  concealed 
beneath  the  surface  cannot  be  known,  f 

In  York  county  the  arch  is  not  symmetrical,  Tocqnan 
axis  being  10  miles  from  the  northern  and  only  five  miles 
from  the  southern  border  of  the  belt.  But  in  Lancaster 
county  the  belt  is  only  about  10  miles  wide  and  the  Tocquan 
axis  is  nearly  central. 

The  Tocquan  arch  seems  to  sink  southwestward  through 
York  county  into  Maryland,  and  rise  eastward  through 
Lancaster  into  northern  Chester,  where  the  Laurentian 
gneiss  comes  up  to  and  occupies  the  present  surface. 

The  lower  strata  along  the  Tocquan  anticlinal  are  thor- 
oughly and  coarsely  crystallized.  Those  above  them,  to- 
wards the  north  and  south  borders  of  the  belt,  are  less  per- 
fectly crystallized,  or  in  much  smaller  masses. 

The  lower  strata  are  distinguished  moreover  by  larger 
amounts  and  larger  specimens  of  muscovite,  and  more  pot- 
ash micas  generally.  The  rocks  are  of  lighter  color,  and 
there  is  often  enough  feldspar  to  make  true  gneiss ;  and 
this  is  the  case  more  and  more  approaching  the  Tocquan 
axis.  Toward  the  edges  of  the  belt,  that  is,  ascending  in 
the  series,  the  strata  become  more  magnesian,  softer  and 
darker,  usually  greenish  or  yellowish  green ;  containing 
large  quantities  of  chloritic  minerals,  and  cut  by  an  extra- 
ordinary number  of  white  quartz  dykes.:}: 

*The  sections  are  given  in  the  Atlas  to  his  Report  of  Progress  CCC.  This 
belt  of  ancient  rocks  has  suffered  from  all  the  earth  movements  of  all  sub- 
sequent ages,  and  its  originally  regular  stratification  has  been  so  warped  and 
fractured,  compressed  and  bent,  that  scarcely  two  exposed  plates  of  rock 
agree  in  presenting  the  same  dip  or  strike.  Accurate  measurements  of 
thickness  are  therefore  impossible.  But  on  the  whole,  the  estimate  given 
in  the  text  may  be  accepted  with  considerable  confidence. 

fDr.  Frazer  could  find  no  rock  strata  on  the  Susquehanna  to  which  he 
thought  the  term  Laurentian  (either  Upper,  or  Lower)  would  properly 
apply  ;  in  other  words,  none  of  the  Chester  and  Delaware  county  gneisses 
which  have  been  called  Laurentian. 

JP.  Frazer,  Gen.  Notes  Geol.  York  Co.,  Proc.  Am.  Phil.  Soc.,  Phila.,  Dec. 
4,  1885,  p.  395. 
9 


130  GEOLOGICAL   SURVEY    OF   PENNSYLVANIA. 

The  whole  belt  seems  destitute  of  metallic  ore  veins  of  any 
kind,  even  iron.  And  what  is  equally  remarkable,  only 
two  very  small  local  trap  dykes  have  been  noticed  in  it  in 
York  county;  one,  near  its  northwestern  border,  on  the 
Maryland  line,  two  miles  east  of  Black  Rock  P.  O.,  and  the 
other,  on  the  Susquehanna  river,  three  miles  north  of  York 
Furnace.  It  is  needless  to  say  that  no  trace  of  fossil  life, 
animal  or  vegetable,  has  been  as  yet  detected  in  these  crys- 
talline schists.  The  country  is  one  of  low  hills,  well 
watered  and  fertile. 

A  better  understanding  of  this  important  belt  of  azoic 
rocks  will  be  got  by  comparing  a  description  of  them 
lately  published  by  one  of  the  geologists  of  the  United 
States  Geological  survey. 

The  Newer  Gneiss  in  Maryland. 

The  Azoic  crystalline  (Tiolocrystailine,  or  completely  crys- 
tallized) belt  of  York  county,  passes  into  Maryland  and  is 
joined  by  the  great  crystalline  belt  of  Chester  and  Dela- 
ware counties,  the  two  belts  encircling  and  holding  in  a  syn- 
clinal the  southwest  end  of  the  Peach  Bottom  phyllite  belt. 

These  Maryland  crystallines  have  been  studied  by  C.  B. 
Keyesof  the  U.  S.  G.  Survey,*  and  described  as  thoroughly 
metamorphosed  highly  feldspathic  sediments,  penetrated 
by  vast  quantities  of  eruptive  materials  often  of  the  same 
composition  as  the  strata  through  which  they  break  ;  in 
other  words,  eruptive  granites  cutting  sedimentary  gneisses  ; 
all  together  foliated  by  pressure,  so  that  in  parts  of  the  area 
they  can  hardly  be  distinguished. 

The  gneisses  which  can  be  certainly  regarded  as  crystal- 
lized sedimentary  beds  are  thus  designated  : 

a.  Typical  Motite  and  biotite  muscomte  (mica)  gneiss, 
highly  feldspathic,  and  in  thin  parallel  layers,  as  in  the 
quarries  on  Jones'  and  Gwynn's  falls  at  Baltimore,  cut  by 
biotite  pegmatite  dykes,  and  full  of  eyes,  lenses,  or  chunks 
of  quartz.     At  Washington  they  hold  well-characterized 
conglomerate  beds. 

b.  Muscomte  (mica)  gneiss,  with  but  little  feldspar,  but 

*See  paper  in  Bull.  G.  Soc.  Amer.,  1891,  Vol.  2,  p.  309. 


THE   NEWER   GNEISS   IN   MARYLAND.  131 

full  of  garnet,  staurolite,  cyanite,  fibrolite,  rutile,  etc.,  and 
cut  with  innumerable  white  quartzite  veins. 

c.  Mica  schist,  without  feldspar,  but  with  garnets,  etc., 
full  of  white  quartz  veins  ;  apparently  a  local  variety  of  b. 

These  are  evidently  the  gneisses,  mica  schists,  garnet 
schists,  and  contorted  and  veined  schists  of  Philadelphia. 

There  are  other  rocks  which  show  little  or  no  signs  of  any 
original  sedimentary  disposition,  such  as: 

d.  Setter's  ridge  quartz-schist,  or  quartzite,  extensively 
quarried  north  of  Baltimore,  and  affording  at  many  other 
places  a  definite  geological  horizon  ;  always  perfectly  foli- 
ated by  parallel  muscovite  mica  layers,  at  variable  distances 
from  each  other  ;  with  plenty  of  stretched  and  broken  tour- 
maline crystals  in  the  foliation  planes. 

e.  Orbicular  quartzite,  compact,  fine-grained,  with  radi- 
ating quartz  crystals  ;  as  at  the  Poor  House  quarry  (along 
the  western  edge  of  the  Texas  augengneiss  area)  and  in  the 
Brooklandville  marble. 

/.  Deer  creek  white  conglomerate  quartzite,  in  the  center 
of  Hartford  county,  four  miles  long  and  less  than  half  a  mile 
wide,  marking  a  sharp,  narrow  300-feet  high  ridge.  Under 
the  microscope  it  is  seen  to  be  completely  re-crystallized, 
but  showing  to  some  extent  the  original  pebbles,  with  a 
secondary  growth  of  wavy  membranes  of  muscovite,  large 
radiating  tufts  of  blue  cyanite,  chlorite,  magnetite,  tourma- 
line, garnet,  rutile.  When  better  studied  this  may  turn 
out  to  be  a  basal  conglomerate  of  the  Peach  Bottom  phyl- 
lite  series,  for  its  outcrop  is  just  along  the  line  which  sepa- 
rates the  phyllite  and  gneissic  areas. 

g.  Marble  (highly  crystallized  magnesia-limestone,  dolo- 
mite) beds  occur  among  these  rocks,  in  irregular,  sharply- 
folded  patches  at  Cockeysville  and  Texas  in  Maryland,  as 
in  Chester  and  Delaware  counties  on  the  Brandy  wine.  Its 
poarse-grained  variety  is  called  "Alum  stone."  It  con  tains 
crystals  of  phlogopite,  tremolite,  white  pyroxene,  tourma- 
line, scapolite,  rutile. 

h.  The  eruptive  rocks  are  :  (1)  With  a  surplus  of  silica  : 
granite,  granitite,  hornblende  granite,  granite  porphyry, 
augengranite  gneiss,  quartz  porphyry  (felsite),  graphic 


132  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

granite  (pegmatite) ;  (2)  With  sufficient  silica :  gabbros  (of 
three  varieties),  norite,  diorite,  hornblendite  and  horn- 
blende-biotite-quartz  diorite;  (3)  With  too  little  silica: 
pyroxenite,  cherzolite,  cortlandite,  and  the  resulting  ser- 
pentine. 

The  certain  or  probable  eruptive  rOcks  cover  half  the 
present  surface  area  of  this  great  belt,  (Keyes,  p.  310,  311.) 
It  is  open  to  doubt,  therefore,  whether  the  large  areas  in 
Delaware  county  colored  on  the  map  accompanying  Report 
C5  as  Laurentian  may  not,  when  well  studied,  come  to  be 
recognized  as  parts  of  the  same  eruptive  system.  For  the 
belt  of  gneisses,  mica  schists,  garnet  schists,  with  steatite 
and  serpentine  and  marble  beds,  which  are  so  finely  exposed 
along  the  Schuylkill,  Crum  creek,  Chester  creek  and  the 
Brandy  wine,  is  evidently  continuous  through  Bucks,  Mont- 
gomery, Philadelphia,  Delaware,  Chester  and  Lancaster 
counties  into  Harford  county,  Maryland,  and  so  south  into 
Virginia. 


THE   AZOIC   HYDRO-MICA   SLATE  FORMATION.  133 


CHAPTER  XIII. 

The  azoic  hydro-mica  slate  formation ;  phyllite  belts  of 
York  and  Lancaster  counties;  South  Valley  Hill  slate 
of  Chester  county. 

The  age  of  the  South  Valley  Hill  formation  has  been  in 
controversy.  Studied  at  the  Schuylkill  and  along  the  south 
side  of  the  Chester  limestone  valley,  where  its  beds  stand 
nearly  vertical,  Dr.  Frazer  saw  it  descending  beneath  the 
limestone  to  rise  again  in  the  North  Valley  Hill  toward  the 
Lancaster  county  line.  Mr.  Hall,  on  the  contrary,  saw  it 
overlying  the  limestone,  in  two  separate  and  distinct  syncli- 
nal basins,  one  of  which  he  represents  upon  his  atlas  map 
(sheet  3)  crossing  the  Schuylkill  and  terminating  at  Marble 
Hall  and  Barren  Hill  in  Montgomery  county.* 

In  Dr.  Frazer' s  cross  sections  from  Quarry ville  to  the 
Pequea,  and  from  Marticsville  to  Neffsville,  i.  e.,  across 
middle  Lancaster  county,  a  thin  hydro-mica  formation  is 
drawn  rising  and  falling  in  many  waves  under  the  great 
limestone  formation  (which  includes  clay  slate  or  argillite 
beds) ;  and  beneath  it  the  great  floor  of  gneiss.  Sometimes 
the  gneiss  is  at  the  surface  ;  generally  the  limestone  ;  occa- 
sional outcrops  ofhydro-mica  slate. 

At  Quarryville  the  Chester  County  Valley  ends,  not  in  a 
point,  but  by  swinging  sharply  round  to  the  north  and  ef- 
fecting a  narrow  neck  connection  with  the  most  southern 
point  of  the  great  limestone  plain  of  Lancaster.  The 
structure  is  not  quite  comprehensible  ;  but  the  valley  lime- 

*The  broad  rounded  end  of  this  streak  of  slate  between  two  streaks  of 
limestone  is  very  suggestive  of  a  spoon-shaped  synclinal.  At  Gulf  Mills, 
west  of  the  Schuylkill,  dips  of  80°  N.  and  85°  and  65°  S.  show  a  synclinal- 
Here  also  in  the  short  nose  are  dips  of  85°  N.  and  75°  S.  showing  a  syn- 
clinal. But  it  is  dangerous  to  construct  curves  out  of  such  high  dips;  and 
Dr.  Frazer  insists  on  reading  the  dips  so  as  to  convert  the  two  synclinals 
into  two  anticlinals.  If  Mr.  Hall's  reading  is  correct,  then  these  slates  must 
be  Hudson  River  No.  Ill,  as  he  makes  them. 


134  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

stone  seems  to  end  as  a  synclinal,  in  a  trough  of  South  Val- 
ley Hill  hydro-mica  slate. 

But  the  phyllite  belts  of  York  county  are  a  long  way  off, 
the  northern  one  stopping  (on  the  map)  in  the  triangle  made 
by  the  Susquehanna  and  Conestoga  above  Safe  Harbor  ;  the 
southern  one  ending  (on  the  map)  eight  miles  south  of 
Quarry  ville.  There  seems  to  be  a  probability  that  the  South 
Valley  Hill  slates  are  geologically  connected  with  the  York 
county  phyllites  as  one  and  the  same  formation  underlying 
the  great  limestone.  In  fact,  as  the  South  Valley  Hill 
slates  are  apparently  several  thousand  feet  thick,  and  as  the 
York  county  phyllites  seem  to  be  of  equal  thickness,  we 
should  look  for  a  great  show  of  them  in  so  complicated  a 
country  were  they  geographically  connected  across  Lancas- 
ter county  between  Quarryville  and  Safe  Harbor,  or  be- 
tween Quarryville  and  Peach  Bottom  ;  certainly  all  around 
the  edges  of  the  great  limestone  plain  of  Lancaster ;  whereas 
that  plain  is  edged  with  quartzite  and  gneiss.  But  not  to 
puzzle  over  this  and  other  collateral  conundrnms  here,  the 
following  description  of  the  phyllites  will  suffice : 

The  main  York  county  phyllite  belt.  * 

As  describe^  by  Dr.  Frazer,  this  extends  from  the  Susque- 
hanna river  below  Wrightsville  (Columbia)  to  the  south- 
west corner  of  York  county,  in  a  gently  undulating  way 
upon  the  map,  and  with  a  breadth  of  three  or  four  miles. 
The  land  is  lower  than  the  crystalline  country  to  the  south- 
east of  it,  and  the  rocks  are  so  decomposed  that  very  few 
outcrops  are  seen,  which  makes  the  geology  obscure.  Dal- 
lastown,  Loganville,  Hetricks  and  West  Manheim  villages 
are  in  this  belt,  and  Glen  Rock  on  the  Northern  Central 
railroad  is  at  its  southeast  edge  where  the  southern  branch 
of  Codorus  creek  issues  from  the  gneissic  belt  of  .the  Toc- 
quaii  anticlinal. 

This  southeastern  edge  (the  northwestern  edge  of  the 
Tocquan  belt)  is  drawn  on  Dr.  Frazer' s  map,  he  says,  not 
in  a  precise  manner,  but  as  an  approximation  to  the  truth  ; 

*Creedner's  term  in  general  use  in  Europe  for  finely-leaved  argillaceous, 
or  clay  slate  strata,  of  which  roofing  slates  are  a  variety. 


THE   MAIN   YORK   COUNTY   PHYLLITE   BELT.  136 

because  the  phyllite  strata  do  not  differ  from  the  Tocquan 
strata  along  the  line  as  if  there  was  an  abrupt  change  from 
a  lower  to  a  higher  series,  but  as  if  both  belonged  to  one 
great  series  becoming  more  slaty  or  schistose  upward.  The 
dividing  line  upon  the  ground  is  therefore  less  definite  than 
it  had  to  be  made  on  a  colored  map.  It  commences  at  the 
river  opposite  Turkey  Hill  in  Lancaster  county,  passes  a 
mile  north  of  Windsor  P.  O.  and  a  mile  south  of  Dallas- 
town  to  Glen  Rock  and  Black  Rock. 

The  strata  are  much  folded  and  distorted  as  they  descend 
northward  beneath  the  clay  slate,  quartzite,  hydro-mica 
slate,  limestone  and  New  Red  strata,  and  rise  to  the  surface 
again,  twenty-five  miles  to  the  northwest,  at  the  foot  of  the 
South  mountain  near  Dillsburg  in  the  northwest  corner  of 
York  county,  where  again  they  seem  to  lie  on  the  older 
schists,  but  are  themselves  covered  by  broken  fragments  of 
quartzite  and  other  rock- wash. 

The  Loganville  trap  dyke,  four  miles  long,  prolonged 
north-northeastward  (after  the  break  of  a  mile)  eight  miles 
further,  crosses  the  phyllite  belt  and  penetrates  the  over- 
lying Silurian  rocks  beyond  it.  Patches  of  Hellam 
(CMques]  quartzite  of  Upper  Cambrian  age  occur,  suggest- 
ing that  it  once  covered  unconformably  and  perhaps  en- 
tirely the  phyllite  belt;  and  the  quartzite  occupies  a  strip  of 
land  along  the  northern  edge  of  the  belt,  west  of  the  river.* 

Some  limestone  beds  occur  in  this  phyllite  series  inter- 
stratified  with  the  slates,  as  at  Glen  Rockf 

*This  fact  by  itself  would  make  impossible  the  suggestion  that  the  phyl- 
lites,  schists  and  gneisses  are  nothing  but  metamorphosed  Silurian  or  De- 
vonian sediments. 

fSmall  thin  lenses  of  marble  occur  in  the  Sericite  belt  of  Maryland,  north 
of  the  B.  and  O.  R.  R.  The  marble  is  extremely  hard  and  of  a  fine,  even 
grain,  the  crystals  almost  requiring  a  lens  to  see  ;  at  the  Westminster  quai- 
ries,  snow-white  ;  more  often  streaked  with  black,  gray  or  red ;  in  contact 
with  the  copper  of  Liberty  and  New  London  and  the  lead  of  Union  Bridge. 
These  marbles  of  the  phyllite  (sericite)  belt  differ  both  from  the  uncrystal- 
line  blue  limestone  of  Frederick  valley  and  from  the  coarse  (loaf-sugar) 
crystalline  magnesian  limestones  (dolomite  marbles)  of  Baltimore  county. 
These  last  hold  crystallized  quartz-clay  impurities,  but  the  phyllite  marbles 
show  narrow  bands  of  sericite  or  chlorite  schist.  (Keyes,  p.  307.)  Fossil 
shells,  "well  characterized,"  are  reported  to  have  been  found  by  Prof.  P.  R. 
Uhler  in  slaty  bands  traversing  the  Westminster  quarries,  which  lie  very 


136  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

Iron  ore  deposits  also  occur  in  this  phyllite  belt,  the 
largest  of  which  are  the  Brillhart  and  Feigley  banks  a 
mile  or  two  east  of  Loganville,  which  Dr.  Frazer  is  disposed 
to  regard  not  as  really  belonging  to  the  phyllite  rocks,  bm 
as  washings  (segregations)  from  later  formations  which  once 
covered  the  phyllite  belt  but  have  been  removed  by  the 
general  rain  erosion  of  the  country. 

The  southern  or  Peacli  Bottom  phyllite  belt. 

This  borders  on  the  southeastern  side  of  the  Tocquan 
gneisses,  and  occupies  a  triangular  area  in  the  southeast 
corner  of  York  county  between  Muddy  creek  and  the  state 
line ;  and  in  it  appear  the  Peach  Bottom  roofing  slates. 
If  these  are  a  part  of  the  series,  it  is  remarkable  that  they 
do  not  appear  in  the  belt  of  phyllites  above  described  on 
the  northwest  side  of  the  Tocquan  gneiss.* 

It  is  quite  evident  that  this  phyllite  area  occupies  a  broad 
synclinal,  and  that  its  strata  are  superimposed  upon  the 
Tocquan  gneiss  series  ;  for  the  phyllite  ends  in  a  point  in 
Maryland  surrounded  by  the  gneiss, f  and  it  seems  to  end 
also  in  Lancaster  county.:}:  There  can  be  no  other  ex- 
planation of  the  geographical  relationships  of  the  phyllite 
and  gneiss  areas.  The  gneiss  area  entirely  surrounds  this 
phyllite  area  ;  therefore,  the  phyllites  must  either  rise  on  an 
anticlinal  or  sink  in  a  synclinal.  The  former  supposition  is 
precluded  by  the  anticlinal  structure  of  the  Tocquan  belt, 

near  the  eastern  border  of  the  phyllite  belt,  in  1880.  Sent  to  the  New  Or- 
leans exhibition,  they  were  lost  before  any  descriptions  or  identifications  of 
them  had  been  made.  (Keyes,  p.  307.) 

*There  is  a  roofing-slate  belt  in  the  heart  of  the  South  mountains;  the 
quarries  were  long  ago  abandoned  because  their  slate  could  not  compete  in 
the  market  with  the  Peach  Bottom  slate.  What  relation  in  geology  the  two 
bear  to  each  other  is  not  known. 

fSee  the  frontispiece  map  of  C.  R.  Keyes'  paper  in  Bulletin  Geol.  Soc- 
Amer.,  Vol.  2,  p.  301.  The  point  nearly  reaches  the  Northern  Central  R.  R, 
25  miles  from  the  Susquehanna  river. 

{See  map  of  Lancaster  county  in  P.  Frazer's  Report  C3,  Atlas,  where  the 
phyllite  area  is  seen  extending  to  five  miles  from  the  river  north  of  the 
Little  Britain,  Lyles  and  Pleasant  Grove  serpentine  belt.  It  does  not  come 
to  a  point,  as  in  Keyes'  map,  but  has  an  indefinitely  square  transverse  ter- 
mination ;  which  merely  indicates  the  fact  that  its  geographical  northeast 
extension  could  not  be  properly  mapped.  See  Chapter  XIX. 


THE   PEACH   BOTTOM   ROOFING   SLATES.  137 

and  the  descent  of  tjie  phyllites  to  form  another  belt  on  its 
north  border,  extending  across  the  Susquehanna  eastward, 
and  across  the  state  line  to  the  Potomac.* 

The  phyllite  belt  is  said  by  Keyes  to  "include  the  semi- 
crystalline  slates  and  finely  fissile  schists  which  compose  so 
large  a  portion  of  the  Piedmont  area  in  Maryland.  They 
are  capable  of  sub-division  into  a  great  number  of  varieties. 
They  are  beyond  doubt  argillaceous  sediments  which  have 
undergone  a  greater  or  less  amount  of  mechanical  (cleav- 
age) and  chemical  (crystallization)  metamorphism,  though 
they  do  not  lithologically  differ  from  beds  which- in  many 
other  localities  are  known  to  be  of  Devonian,  Silurian,  or 
Cambrian  age.  Their  most  important  mineralogical  compo- 
nent is  a  silky  white  mica  (sericite  or  Kaolin),  whose  indi- 
vidual scales  vary  greatly  in  size  in  different  specimens. 
This  is  sometimes  wholly  or  in  part  replaced  by  green 
chlorite,  with  inter-beds  of  chlorite  slate.  Quartz  grains 
are  common  \feldspar  very  rare  (perhaps  because  changed  to 
white  mica);  iron,  in  red  hexagonal  plates  (or  rounded  grains) 
common,  often  so  abundant  as  to  make  the  rock  an  ore ; 
minute  tourmaline  crystals  very  common ;  microscopic 
rut  He  needles  everywhere  abundant;  ottrelite  finely-de- 
veloped in  some  beds.  The  phyllite  cleavage  is  always  per- 
fect, and  of  a  satiny  lustre  increasing  in  proportion  to  the 
mica  present,  and  of  various  shades  of  pale  grey,  green, 
blue,  purple  and  black  (roofing  slates).  The  original  sedi- 
mentation is  attested  by  round  grains  and  small  pebbles  of 
various  composition.  Where  least  disturbed  the  slates  are 
jointed  and  cut  by  cross  seams  of  chlorite  or  quartz  ;  where 
more  disturbed  they  are  puckered  and  filled  with  veins  and 
eyes  of  quartz. 

The  Peach  Bottom  roofing  slates. 

As  described  by  Dr.  Frazer,+  this  narrow  belt  extends 
southwestward  from  Peters  creek  in  Lancaster  county, 

*This  settles  one  of  the  great  Azoic  questions,  and  Dr.  Frazer  should  have 
the  credit  ot  predicting  its  settlement  and  furnishing  the  evidences,  which 
Mr.  Keyes  confirms. 

fSecond  Geol.  Survey  Pa.,  Report  of  Progress  C3,  1877,  pages  179  to  190- 
Proc.  Am.  Inst.  Min.  Eng.,  Troy  meeting,  1883.  Proc.  Am.  Philos.  Soc. , 
Phila.,  Dec.  4,  1885,  page  398. 


138  GEOLOGICAL   SURVEY  OF   PENNSYLVANIA. 

across  the  Susquehanna  river  and  the  southeast  corner  of 
York  county  into  Maryland.  They  are  exposed  to  view  in  a 
line  of  quarries  in  both  the  adjoining  states  about  nine  miles 
long.  *  On  Peters  creek  the  black  slates,  150'  wide,  dip  64°  (S. 
40°  E.)  under  the  adjoining  crystalline  schists. f  Here  the 
old  slate  quarry  of  the  Browns,  after  being  operated  for  a 
century,  was  bought  by  Bonsall  &  Yard  and  was  in  full  play 
in  1876,  one-half  the  width  of  the  belt  being  rejected  as 
bony,  and  new  quarries  being  commenced  in  view  of  the 
unprofitable  depth"  of  the  old  one.  Masses  weighing  500  to 
1,000  pounds  are  blasted,  lifted  and  sawn  into  lengths. 
The  slates  are  not  as  smooth  and  black  as  the  best  from 
Slatington  &  Chapman  in  Lehigh  county.  They  have  a 
fine  grain,  but  are  liable  to  show  incipient  traces  of  flebby 
or  bubbly  texture  even  in  the  finest  parts  of  the  best 
varieties.  In  sunlight  they  have  a  purplish  lusier.  They 
are  so  smooth  and  soft  to  the  touch  and  so  tough  that  nails 
may  be  driven  through  them,  and  they  weather  well.  They 
are  split  into  roof  slates  with  BonsalFs  patent  knife. 
Mantles,  tables,  tombstones,  etc.  are  sawn  and  finished  on 
a  large  horizontal  wheel.  Much  of  the  quarry  rock  is  re- 
jected, but  part  of  the  great  refuse  piles  is  ground  into  flour 
for  paint,  cement  and  roof  slating4 

In  York  county  the  slate  ridge  is  well-marked  and  well- 
wooded,  but  neither  high  nor  steep,  with  a  rather  uniform 
outline,  its  summit  striking  southwest,!  the  village  of  Delta 

*See  C3,  p.  182,  plate  7,  view  of  Humphrey's  quarry,  near  Delta,  York 
county,  and  p.  184,  plate  8,  view  of  Jones  <fe  Co.'s  quarry,  in  Harford  county, 
Md.,  both  from  photographs. 

fC3,  p.  179. 

JThe  only  other  quarries  on  this  (east)  side  of  the  river,  owned  by  Oole- 
man  <fe  Co.,  were  not  operated  in  1880.  In  York  county  the  first  quarry  is 
2i  miles  from  the  river,  near  Slate  Hill  P.  O. 

§In  J.  Humphrey  <fe  Co.'s  northern  quarry  the  long  excavation  (of  best 
slate)  points  S.  55°  W.  The  neighboring  Old  Revolutionary  bank,  full  of 
water,  points  S.  40°  W.  In  Williams  &  Co.'s  quarry,  which  is  large  and 
deep,  but  nearly  full  of  water,  the  hanging  wall  strikes  S.  55°  to  60°  W.  In 
the  next  quarry  the  nearly  vertical  slates  strike  S.  40°  W.  (The  ridge  itself 
at  W.  Bangor  strikes  S.  45°  W.)  In  E.  Davis'  quarry  a  remarkable  cross 
dip  of  87°  (to  S.  40°  W.)  demands  special  notice.  At  the  west  end  of  W- 
E.  Williams'  quarry  the  slates  dip  88°  (X.  10°  W.)  with  a  strike  of  S.  80° 
W.  ;  but  in  the  main  they  are  vertical  and  strike  S.  40°  W.  In  W.  C.  Rob- 


THE   PEACH    BOTTOM   ROOFING-SLATES.  139 

being  built  on  its  northwest  slope,  and  most  of  the  quarries 
opened  on  its  southeast  slope  ;  with  dips  very  steep,  nearly 
vertical,  and  preponderatingly  to  the  N.  W.  on  the  quarry 
side. 

The  whole  ridge  is  by  no  means  good  quarry  ground,  as 
is  shown  by  the  great  number  of  abandoned  trial  shafts. 
Even  the  long-wrought  merchantable  strata  are  capricious 
and  change  quality  both  lengthwise  and  downward,  requir- 
ing very  judicious  mining.  While  the  whole  ridge,  half  a 
mile  wide,  is  of  slate  the  paying  belt  (as  at  John  Hum- 
phrey &  Co.'s  quarry)  averages  only  60  or  70  feet,  of  which 
total  only  40  or  50  feet  of  the  best  slates  are  got  from  a 
number  of  narrow  benches.  This  excavation  is  about  500' 
long,  50'  to  70'  wide,  and  175'  deep  at  its  deepest  place.  A 
gradual  change  of  quality  took  place  in  sinking  the  first 
40',  but  after  that  the  quality  remained  constant  to  the 
bottom,  and  no  doubt  would  be  found  the  same  to  an  indefi- 
nitely greater  depth. 

The  roofing  slate  belt  seems  to  belong  to  and  be  an  inte- 
gral part  of  the  great  "chlorite  slate"  formation.  Such  was 
the  impression  produced  upon  Dr.  Frazer  by  his  official 
study  of  it  in  1877.*  The  marketable  slate  beds  are  inter- 
leaved with  others  which  may  be  properly  named  chlorite 
schists.  On  the  railroad  at  the  river  bank  the  width  of  the 

erts'  quarry  the  jointage  planes  which  govern  the  excavation  dip  45°  (S.  40° 
to  50°  W.,)  but  in  one  of  the  best  exposures  the  slates  dip  only  20°  (N.  30° 
W.,)  making  the  strike  S.  60°  W.  In  J.  Humphrey  &  Co.'s  quarry  the  ver- 
tical slates  strike  S.  60°  W.,  and  a  jointage  plane  dips  30°  (S.  70°  W.)  T.  W. 
Jones  <fc  Co.'s  quarry  adjoins  the  last  In  J.  W.  Jones  <fe  Co.'s  quarry  the 
vertical  slates  strike  regularly  S.  40°  W.  One  jointage  plane  system  dips  30° 
(S.  40°  W.)  ;  the  other  80°  (S.  60°  W.)  In  Hugh  E.  Hughes'  quarry,  close 
to  the  last,  the  nearly  vertical  slates  (slightly  north  dip  at  one  end  and 
slightly  south  dip  at  the  other)  strike  about  S.  40U  W.  with  several  jointage 
systems,  one  of  them  dipping  50°  (S.  40°  W.,)  producing  an  extra  amount 
of  waste.  No  valuable  slates  have  been  found  further  on  in  Maryland. 

*Report  C3,  1880,  page  23,  where  he  proposes  the  theory  that  the  local  pro- 
duction of  roofing  slate  has  been  eftected  by  the  heat  of  a  trap  dyke,  eighteen 
miles  long,  which  traverses  the  schist  country  of  south  Lancaster,  passes 
near  the  northeast  end  of  the  roofing  slate  belt  and  follows  it  to  the  river. 
This  theory  could  be  more  easily  accepted  if  trap  appeared  along  the  whole 
range  of  the  slate  hill  in  York  county  and  Maryland  ;  if  other  belts  of  slate 
were  seen  along  the  course  of  the  dyke  further  north  ;  and  if  trap  was  not  un- 
known in  the  Lehigh  roofing  slate  region  and  in  Vermont. 


140  GEOLOGICAL   SUKVEY   OF   PENNSYLVANIA. 

slate  belt  is  about  400  feet ;  but  the  really  valuable  roofing 
slates  recur  through  this  distance  in  special  belts,  or  layers, 
each  only  a  few  yards  thick.  The  country  on  each  side  (up 
and  down  river)  is  sharply  plicated  ;  and  the  slate  rocks  ex- 
posed about  100  yards  north  of  the  slate  factory  (some 
dipping  58°,  S.  55°  E.,  others  62°,  S.  25°  E.)  "resemble  the 
genuine  marketable  slates  in  many  features,  but  are 
greener,  more  chloritic,  and  very  much  convoluted."  A 
close  examination  of  the(  texture  of  the  rocks  suggests  a 
growing  belief  in  "an  insensible  alteration  of  the  more 
chloritic  hydro-mica  schists  into  the  dark  purple-black 
Peach  Bottom  slates."* 

A  chemical  analysis  of  a  piece  of  Peach  Bottom  roofing 
slate  from  the  Humphrey  quarry,  made  by  Mr.  A.  S.  Mc- 
Creath,f  shows  that  it  is  an  almost  non-magnesian  clay- 
slate,  holding  9  per  cent,  of  ferrous  oxide  and  blackened  by 
2  per  cent,  of  carbon 4  If  this  be  a  fair  representation  of 
the  composition  of  the  mercantile  slate  layers  of  the  belt, 
no  theory  of  igne'ous  alteration  from  an  original  chlorite 
(magnesian)  sediment  can  be  accepted  ;  for  the  action  of  a 
trap-dyke  would  add,  not  abstract,  magnesia.  We  must 
therefore  regard  the  good  slate-plies  as  separate  and  con- 
secutive layers  or  beds  of  iron-clay,  foliated  by  pressure  ; 
like  the  roofing  slate  beds  of  Lehigh  county,  but  of  a  much 
earlier  age  ;  therefore  they  may  possibly  be  identical  with 
the  Lowest  Cambrian  slates  of  Georgia  county,  Vermont, 
which  hold  the  Olenellu* fauna  of  Walcott.§ 

No  animal  fossils,  no  trilobites,  have  been  noticed  in  these 
slates ;  but  on  the  surfaces  of  many  slabs  are  seen  shining 
ribbons,  crossing  each  other,  which  seem  to  be  fossil  plants, 

*C3,  page  133. — A  specimen  from  J.  Humphrey  &  Co.'s  quarry  shows  a 
fragment  or  unaltered  mica-schist  in  the  mass  of  fine  slate  (03,  p.  190).  In 
W.  E.  Williams'  quarry  a  seam  of  chlorite  slate  and  quartz,  mixed  with 
manganiferous  iron  oxide,  occurs  in  streaks  (C3,  p.  188). 

fReport  MM,  p.  370  (Copied  into  C3,  p.  270). 

jSilica,  50;  alumina,  22;  ferrous  oxide,  9;  carbon,  2;  water,  3.4;  potash, 
3.6;  magnesia,  1.5;  titanic  acid,  1.3;  manganous  oxide,  0.6;  soda,  0.5;  lime, 
0.2;  iron  disulphide  and  sulphuric  acid,  each  less  than  0.1;  and  a  trace  of 
cobalt. 

§See  Diet,  of  Fossils  Report  P.  4.  See  also  chapter  on  Cambrian  fossils 
further  on. 


THE   PEACH   BOTTOM    ROOFING-SLATES.  141 

probably  sea  weeds  allied  to  Buthotrephis,  but  of  uncer- 
tain species  and  even  genus,  and  lending  no  aid  to  the  de- 
termination of  the  age  of  the  formation.*  It  would  be 
unsafe  to  assign  it  to  the  Lower  Silurian  age  of  the  roofing 
slate  formation  of  Lehigh  county  on  the  strength  of  these 
fossil  plants.  There  is  no  good  evidence  in  favor  of  the 
Peach  Bottom  slate  ridge  being  an  isolated  distant  outlying 
basin  of  Hudson  river  slate  preserved  in  one  of  the  many 
folds  of  the  Chlorite  slate  country ;  nor  is  there  any  easy 
mode  of  explaining  the  presence  on  the  Maryland  line  of 
such  an  outlier  of  the  Lehigh  valley  slate  belt  either  by 
conformable  deposition  or  by  downthrow  faulting.  For  the 
present  we  must  be  content  to  be  guided  by  the  -lately  im- 
proved classification  of  the  Cambrian  slates  of  Canada, 
Vermont,  and  the  eastern  counties  of  New  York ;  and  to 
consider  the  Peach  Bottom  slates  as  part  of  that  early  sys- 
tem ;  at  all  events,  integral  members  of  the  chlorite  schist 
formation  in  which  they  lie.f 

*Peacb  Bottom  slates,  etc.,  Proc.  Amer.  Inst.  Mining  Engineers,  Troy 
meeting,  1883.  These  Peach  Bottom  tossils,  found  by  Rev.  I.  N.  Rendall, 
D.  D.,  President  of  Lincoln  University  in  Chester  county,  at  the  quarries 
near  Delta  in  York  county,  were  submitted  to  Prof  James  Hall,  of  Albany, 
who  thought  them  more  like  the  Buthotrephis  of  the  Hudson  river  slate 
(formation  No.  Ill)  than  anything  else. 

Prof.  J.  S.  Starr,  of  Franklin  and  Marshall  College,  exhibited  some  spec, 
imens  to  the  Linnean  Society  in  Lancaster,  some  of  which,  in  his  opinion, 
had  an  ill-defined  resemblance  to  "ferns."  See  a  report  of  the  paper  in  the 
"New  Era,"  of  Lancaster,  May  15, 1886. 

These  fossil  ribbons  do  not  stand  alone ;  for  in  certain  black  silicious  slates 
near  St.  John  occur  "black,  linear,  flat  objects  that  appear  to  be  of  the  nature 
of  sea-weeds  or  graptolites,  but  not  sufficiently  complete  to  give  a  satisfac. 
tory  indication  of  their  relationship."  (G.  F.  Matthew  on  "Eozoon  and 
other  low  organisms  in  Laurentian  rocks  at  St.  John,"  in  Bull.  No.  IX, 
Nat.  Hist.  Soc.  New  Brunswick,  read  Oct.  7,  18900  Jt  was  in  specimens 
from  a  neighboring  limestone  of  the  same  age  that  Sir  William  Dawson 
many  years  ago  detected  fragments  of  Eozoon  Canadense. 

fThere  is  nothing  to  astonish  us  in  the  belt  terminating  eastward  near  the 
river  and  not  running  on  through  Lancaster,  Chester  and  Delaware  counties 
to  the  Schuylkill,  more  than  in  the  Northampton  and  Lehigh  roofing  slate 
belt  terminating  westward  near  the  Berks  county  line,  instead  of  running 
continuously  across  the  Susquehanna  and  Potomac  rivers  far  into  Virginia. 
In  both  cases  the  mechanical  agency  for  foliating  the  formation  into  roofing 
slate  operated  generally,  but  the  particular  kind  of  clay  formation  capable 
of  being  foliated  was  of  limited  extent. 


142  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 


CHAPTER  XIV. 

Geology  of  the  South  Mountains. 

The  South  mountains,  separating  the  Cumberland  valley 
from  the  lower  country  of  York  and  Adams  county,  are  the 
northernmost  end  of  the  Blue  ridge  range  of  Virginia,  The 
highest  summit  rises  only  to  2,100'  A.  T.  There  are  no 
rocky  peaks,  and  very  few  cliffs.  The  slopes  are  all  mod- 
erate and  the  surface  everywhere  rounded  on  a  grand  scale. 
The  long,  straight,  sharp,  rocky  crests  and  boldly- terraced 
steep  slopes  of  middle  Pennsylvania  are  almost  unknown 
to  this  mass  of  irregularly-arranged  groups  of  rounded 
knobs  and  shallow  valleys,  for  the  most  part  bare,  uncul- 
tivated, or  covered  with  a  low  second  growth  of  forest  re- 
served for  abandoned  iron  works  of  the  old  style.* 

The  whole  measures  upon  the  map  ten  miles  in  breadth 
by  fifty  in  length,  upon  a  curve  extending  from  the  Mary- 
land line  to  its  northeastern  end  fifteen  miles  west  of  Har- 
risburg.  It  ends  like  the  human  hand  in  four  blunt  fingers 
and  a  very  short,  small  thumb  on  the  Cumberland  valley 
side.  These  five  terminals  slope  with  considerable  beauty 
down  to  the  plain  country  of  northern  York  county  com- 
posed of  Trias  rocks,  and  of  eastern  Cumberland  composed 
of  Lower  Silurian  limestone,  the  two  parts  of  the  plain  being 
separated  by  the  lower  reach  of  Yellow  Breeches  creek, 
which  in  the  greater  part  of  its  course  flows  close  at  the 
northern  foot  of  the  mountain  mass. 

Many  brooks  descend  from  the  mountain  through  short 
and  rather  steep  ravines  to  Yellow  Breeches  creek  at  its 
foot.  At  one  place  only  in  Cumberland  county  is  the 
mountain  mass  breached  to  let  out  the  rainfall  of  its  in- 
terior surfaces.  This  is  at  Papertown,  called  Mt.  Holly 

*See  description  of  conglomerate  ridges  on  p.  148. 


GEOLOGY   OF   THE   SOUTH   MOUNTAINS.  143 

Springs,  opposite  Carlisle,  where  Mountain  creek,  after 
flowing  east  in  a  valley  twenty  miles  long,  turns  north  and 
issues  through  a  fine  gorge  to  join  the  Yellow  Breeches. 

Mountain  creek  heads  in  the  corner  of  Adams  county  at 
a  summit-divide  from  which  Conococheague  creek  flows 
southwestward  on  the  same  line  with  Mountain  creek  but 
in  the  opposite  direction  (that  is,  along  a  valley  common 
to  both)  to  the  Gettysburg-Chambersburg  turnpike  at 
Greenwood  Furnace  in  Franklin  county,  where  it  turns 
northwest  and  breaks  out  of  the  mountain  opposite  Cham- 
bersburg,  exposing  another  rock  section  analogous  to  that 
at  Mt.  Holly  Springs. 

Here,  at  the  pike,  the  Mt.  Holly  mountain  range,  which 
is  the  highest  and  most  regular  part  of  the  South  mountain 
mass,  virtually  ends,  sinking  southwestward  into  the  Cum- 
berland valley.-  The  lower  interior  ridges  however  run  on 
past  Greenwood  and  Mont  Alto  to  sink  beneath  the  lime- 
stone cove  of  the  Little  Antietam  East  Branch  creek,  oppo- 
site Waynesburg,  near  the  Maryland  line. 

Thus  the  northwest  face  of  the  South  mountain  mass  is 
set  back  from  the  Cumberland  valley,  once  opposite  Cham- 
bersburg  for  four  miles,  and  again  opposite  Greensburg  for 
nearly  five  miles.  It  is  this  that  produces  the  curve  of  the 
mass  upon  the  map.  But  these  backsets  would  narrow  the 
mass  to  a  point  on  the  Maryland  line  were  it  not  for  corres- 
ponding outsets  of  its  eastern  face  in  Adams  county,  one 
at  the  pike  near  Coxtown,  and  another  further  south. 

It  is  evident  that  the  curve  of  the  mass  is  not  produced 
by  a  curving  of  the  ridges  which  compose  it,  but  by  an 
eschelon  arrangement  of  its  ridges  running  past  each  other, 
like  the  synclinal  spurs  of  the  Broad  mountain  in  Schuyl- 
kill  county,  or  the  anticlinal  spurs  of  the  Buffalo  mountains 
in  Union  and  Snyder  counties. 

This  geographical  eschelon  arrangement  of  the  South 
mountains  is  a  good  indication  of  their  geological  structure. 
It  renders  it  probable  that  the  strata,  whatever  may  be  their 
age,  have  been  thrown  into  a  series  of  anticlinal  and  syn- 
clinal waves  entirely  analogous  to  those  with  which  the 
Palaeozoic  country  of  middle  Pennsylvania  have  made  us  so 


144  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

well  acquainted.  It  explains  also  the  finger  arrangement  of 
the  eastern  end  of  the  mass  in  the  Susquehanna  river 
country  ;  and  leads  us  to  suppose  that  the  South  mountain 
series  descends  beneath  Lancaster,  Dauphin  and  Lebanon 
counties,  and  is  in  some  unexplained  way  connected  with 
the  Highlands  of  Berks,  Lehigh  and  Northampton  counties, 
New  Jersey  and  New  York.  But  it  does  not  in  the  least 
help  us  in  solving  the  problem  why  the  South  mountain 
rocks  seem  to  be  absent  from  that  Highland  country. 

The  South  mountain  rocks  are  mostly  quartzites  and 
quartz  slates  ;  those  Highland  rocks  are  mostly  hornblendic 
and  quartz  gneisses,  merely  veneered  with  quart zite  patches. 
If  the  Htironian  (or  Cambrian)  quartzites  are  in  such  force 
in  the  South  mountains,  why  do  they  make  so  accidental 
and  superficial  an  element  in  the  Highlands  \  On  the  other 
hand,  why  are  none  of  the  Highland  gneisses,  especially  the 
hornblendic  schists,  seen  in  the  South  mountains?  The 
underground  interval  is  but  sixty  miles. 

Two  groups  of  rock  compose  the  South  mountain  mass, 
as  shown  in  Dr.  Frazer's  cross-sections.*  The  northwestern 
(Mt.  Holly)  ridge  is  made  by  several  thousand  feet  of  the 
the  lower  quartzite  and  quartz  conglomerate  beds.  The 
southeastern  (Adams  county)  ridges  are  made  by  several 
thousand  feet  of  an  overlying  feldspathic,  micaceous  and 
chloride  series,  intersected  by  veins  of  milky  quartz ;  the 
felsites  varying  in  character  "from  a  sandy  and  earthy  slate 
in  which  the  crystals  of  orthoclase  feldspar  are  very  much 
decomposed,  indeed  are  almost  clay,f — through  a  jasper- 
like  variety — to  a  massive  and  coarsely  porphyritic  struc- 
ture in  which  it  is  suited  to  be  used  as  an  ornamental  build- 
ing stone." 

These  two  series,  or  great  sub- divisions,  seem  at  some 
places  to  graduate  into  each  other,  as  if  they  were  the 
earlier  and  later  deposits  of  one  age.  In  other  places  (as  in 
the  Greenwood  section  No.  10.)  they  seem  distinct;  the 
passage  from  the  lower  quartzite  series  to  the  higher  por- 

*Especially  well  shown  by  his  Section  No.  8,  Report  CC,  page  285. 
fCompare   Fontaine's  "Kaolin   slate"  beds  in   the  Virginia   Blue  Ridge 
section  at  Balcony  Falls,  on  James  river. 


GEOLOGY  OF  THE  SOUTH  MOUNTAIN.        145 

phyritic  (orthofelsite)  series  being  abrupt ;  with  even  an 
apparent  difference  of  strike  in  some  of  the  outcrops  along 
the  line  of  section. 

The  lower,  or  quartzlte  and  conglomerate  slate  series,  is 
certainly  immensely  thick.  Its  beds  very  generally  dip 
southeastward  at  angles  varying  from  20°  to  60°.  Occasion- 
ally they  dip  steeply  the  other  way  (northwest)  implying 
anticlinal  and  synclinal  rolls  ;  but  on  the  whole  they  are 
elevated  towards  the  Cumberland  valley,  as  if  they  once 
passed  in  the  air  over  the  Silurians  of  that  valley,  which  is 
a  clear  impossibility. 

A  master  fault  must  therefore  run  along  the  northwest 
foot  of  the  mountains,  along  the  low  drift-filled  valley  of 
Yellow  Breeches  creek,  in  which  nowhere  can  any  rock  be 
seen  in  place,  but  only  a  series  of  brown  hematite  (limonite) 
iron  ore  deposits,  some  of  them  of  great  size  and  once  ex- 
tensively mined  in  open  quarry  work.  The  northwest  face 
of  the  mountain  mass  is  therefore  in  fact  the  eroded  basset 
edge  of  the  quartzite  series  dipping  away  from  the  fault.* 

The  thickness  of  the  quartzite  and  conglomerate  series 
may  be  imagined  from  cross-section  No.  10,  laid  2^  miles 
north  of  Greenwood,  along  which  for  five  miles  quartzite 
beds  on  a  prevailing  southeast  dip  are  either  seen  or  indi- 
cated, suggesting  a  total  thickness  of  fourteen  thousand 
feet  (14,000').  Other  sections  across  the  mountains  towards 
Mount  Holly  Springs  (even  on  a  rolling  construction  to  sat- 
isfy every  observed  abnormal  dip)  exhibit  a  certain  mini- 
mum thickness  of  5,000',  and  possible  maximum  thickness 
of  10,000'  and  12,000'  of  the  quartzite  series  f  And  if  a 

*Mr.  Lehman's  topographical  map  shows  southeast  dips  all  along  the 
summits  on  the  northwest  edge  of  the  mountain  mass  ;  and  they  are  dips  so 
low  that  they  cannot  bespeak  an  overturn.  They  continue  to  the  Cono- 
cocheague  backset;  here,  however,  they  swing  round  and  become  southwest 
dips  ;  the  quartzites  sinking  beneath  the  limestones  instead  of  being  thrust 
up  over  them,  as  along  the  fault. 

|A  rather  wild  theory  has  been  recently  advanced  by  geologists  studying 
this  range  on  .the  Potomac  at  Harper's  Ferry,  that  the  quartzites  of  the 
west  side  of  the  South  mountain  mass  are  the  same  as  the  Medina  sandstone 
beds  of  the  North  mountain  on  the  west  side  of  the  Cumberland  (Shen- 
andoah)  valley.  They  claim  that  the  structure  along  the  river  makes  this 
evident.  But  if  so.  then  the  same  should  be  the  case  in  Pennsylvania.  But 
10 


146  GEOLOGICAL   SURVEY    OF   PENNSYLVANIA. 

master  fault  really  exists,  as  it  must,  along  the  foot  of  the 
mountain  slope,  there  is  no  knowing  how  much  more  at  the 
bottom  is  buried  against  the  fault  One  single,  perfectly 
regular  and  continuous  outcrop  of  these  southeast  dipping 
strata  was  measured  by  Mr.  Lehman,  at  my  request,  near 
Mt.  Holly  hotel,  giving  a  thickness  of  1,200'.  In  Section 
No.  11.  near  the  Gettysburg-Chambersburg  turnpike,  there 
appear  to  be  3,200'  of  quartzite  and  6,400'  of  "schistose  con- 
glomerate," Dr.  Frazer'  s  Mountain  Creek  Rock  sub  -series.* 
The  thickness  of  the  overlying  felspathic  felsite  series, 

it  is  only  necessary  to  compare  the  thickness  of  the  Medina  with  the  figures 
in  the  text  above  to  show  that  the  theory  is  a  mere  conjecture.  The  Medina, 
opposite  Mt.  Holly  Springs,  is  only  a  few  hundred  feet  thick,  and  increases 
in  thickness  to  2,000'  in  the  direction  of  the  Allegheny  mountain.  See  the 
Perry  Co.  Report,  F2,  and  the  Blair,  Bedford,  Huntingdon  (T,  T2,  T3)  and 
other  reports  of  middle  Pennsylvahia.  It  also  increases  greatly  in  thick- 
ness towards  the  Delaware  river;  but  to  and  beyond  the  Potomac  it  de- 
creases in  thickness  until  it  is  only  forty  (40)  feet  thick  in  E.  Tennessee 
west  of  Knoxville.  Those  who  wish  to  see  the  grounds  on  which  Messrs. 
Geiger  and  Keith  rest  their  identification  of  the  Massannuttan  (Medina 
No.  TV)  sandstone  with  the  quartzite  of  the  Blue  Ridge  at  Harper's  Ferry  ( 
will  consult  their  sketch  map  and  sections  published  in  the  Bulletin  of  the 
Geol.  Soc.  America,  Vol.  2,  p.  158,  where  the  crests  are  represented  as 
synclinals  of  IV,  supported  by  shale  of  III,  overlying  the  limestones  of  II, 
unconformably  resting  on  epidote  schists  and  granite.  The  parallel  syncli- 
nals are  represented  as  compressed  and  overthrown  westward. 

It  has  been  long  known  that  the  Silurians  rode  over  the  Blue  ridge  and 
South  mountain  rocks.  This  is  evident  in  the  case  of  the  Highlands  ot 
Northampton  county  ;  evident  in  Lancaster  and  York  counties  ;  evident  in 
the  James  river  country  ;  therefore  there  is  no  objection  whatever  to  lime- 
stone synclinals  capped  by  shale  and  sandstone  (III,  IV)  on  the  Blue 
Ridge.  Mr.  Keyes'  section  (Bull.  Geol.  Soc.  Amer.,  Vol.  2,  page 320)  shows 
the  Chazy  and  Trenton  with  tneir  characteristic  fossils  on  theeastsideofthe 
range  (between  Cotocton  mountain  and  Sugar  Loaf,  in  Maryland).  Cotocton 
mountain  sandstone  may  possibly  be  Hellarn  (Chiques)  quartzite  No.  I,  and 
Sugar  Loaf  certainly  is  ;  but  nothing  can  suffice  to  identify  the  Medina  with 
the  vast  quartzite  masses  of  our  Mt.  Holly  range. 

But  the  greatest  obstacle  to  finding  the  Medina  in  or  on  the  range  is  the 
vast  thickness  of  the  limestones  of  II  and  slates  of  III  on  which  the  Medina 
lies.  Any  outlying  crest  of  Medina  would  be  supported  by  at  least  5,000  feet 
of  these  limestones  and  slates,  and  if  preserved  by  erosion  in  the  body  of  the 
Blue  Ridge  range  of  Maryland  and  Pennsylvania,  could  only  be  so  pre- 
served at  an  elevation  of  5, 000  feet  above  tide.  This  topographical  necessity 
js  fatal  to  the  hypothesis,  even  if  profound  downthrow  faults  be  substituted 
conjecturally  for  synclinals.  It  is  remarkable  that  Messrs.  Geiger  and  Keyes 
do  not  explain  the  absence  of  the  limestone  from  their  map. 

*CC,  p.  295,  and  Section  No.  II. 


GEOLOGY    OF  THE   SOUTH   MOUNTAIN.  147 

along  the  Mt.  Holly  cross-section,  No.  8,  exceeds  6,000',  as 
shown  in  the  broad  synclinal  with  opposite  dips  of  from 
30°  to  50°  at  the  southern  end  of  the  section.  The  highest 
b^ds  left  in  the  center  of  this  basin  are  green  crystalline 
schists  and  orthofelsites.  How  many  still  higher  beds  have 
been  removed  by  erosion  cannot  be  known.  In  Section  No. 
11,  near  the  G.  and  C.  turnpike,  a  small  synclinal  holds 
700'  or  800'  of  hydro-mica  slates,  and  over  these  a  continu- 
ous monoclinal  exhibition  of  orthofelsite  a  mile  and  a  half 
long,  ''representing  (if  there  be  no  unknown  reverse  dips) 
nearly  5,000  feet  of  strata"  (CC,  p.  295). 

The  Mountain  Creek  Rock  sub-division  of  the  Lower 
series  is  characterized  by  scattered  pebbles  and  by  occa- 
sional solid  beds  of  conglomerate.  Dr.  Frazer  gives  it  various 
names  descriptive  of  its  varieties:  "Schist  conglome- 
rate," "chlorite  schist  conglomerate,"  "quartz  conglomerate 
schist."  "green  schist  with  quartz  pebbles,"  "hydro-mica 
schist  with  pebbles"  (some  of  them  of  transparent  quartz, 
others  of  amethyst-colored  quartz),  these  last  two  varieties 
of  conglomerate  marking  a  transition  to  the  Upper  series. 
It  is  evident  that  the  great  Lower  series,  if  indeed  it  be  sep- 
arable from  the  Upper,  has  a  lowest  set  of  beds  which  are 
almost  wholly  of  metamorphosed  sand,  quartzite.  Then 
higher  sets  of  clay,  sand  and  pebble  beds,  metamorphosed 
into  quartzoze  slates,  shales,  schists  and  pebble  rock. 

The  still  higher  and  more  or  less  magnesian  slates, 
hard  shales,  crystalline  schists  with  scattered  pebbles, 
conglomerate  beds,  and  porpyhritic  beds,  make  an  indefi- 
nite but  recognizable  Upper  system,  in  which  also  occur  true 
quartzite  beds,  like-those  at  the  bottom  of  the  Lower  series. 
Occasional  fragments  of  diorite  trap  appear  on  the  surface, 
which  may  indicate  interbedded  volcanic  rocks,  or  possibly 
very  small  dikes.  The  whole  may  have  been  capped  by 
the  Hellam  (Chiques  rock)  quartzite,  fragments  of  which 
are  so  abundant  on  the  lower  southeast  slope  of  the  South 
mountain  mass. 

It  is  hard  to  avoid  the  inference  that  our  South  mountain 
rocks  represent  the  Huronian  section  of  Murray  and  Logan. 

It  is  impossible  not  to  compare  them  also  with  the  great 


148  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

quartzite  masses,  the  roofing  slates,  etc.,  of  Wolcott's 
upper,  middle  and  lower  Cambrian  system.* 

The  conglomerate  beds  sometimes  make  bold  features  in 
the  scene.  North  of  the  pike  at  Greenwood  a  narrow  valley, 
one  or  two  hundred  feet  in  depth,  is  shut  in  by  a  straight 
sharp-crested  little  ridge  produced  by  a  few  beds  of  coarse 
conglomerate,  in  all  not  more  than  fifty  feet  thick,  whose 
fragments  are  piled  along  the  narrow  top,  strew  the  steep 
northwestern  basset  slope  and  choke  up  two  wild  little 
ravine  gaps  through  which  the  drainage  of  the  back-valley 
relieves  itself.  One  is  appropriately  called  Dark  Hollow. 
The  dip  of  the  conglomerate  beds,  and  of  all  the  strata  on 
both  sides  of  the  ridge,  is  uniformly  about  45°  S.  E.  On 
the  S.  E.  slope  of  the  ridge,  and  therefore  about  a  hundred 
feet  geologically  above  the  conglomerates,  is  the  outcrop  of 
a  five  or  six-foot  bed  of  iron  ore,  tunneled  to  and  mined  by 
Thad.  Stevens  for  the  use  of  his  Caledonia  furnace  at  the 
pike.  I  was  not  able  to  trace  the  conglomerate  to  the  pike; 
but  the  ridge  is  represented  topographically  that  far ;  and 
what  seems  to  be  the  same  iron  ore  bed,  or  one  at  about  the 
same  horizon,  was  opened  and  mined  a  little  at  the  foot  of 
the  steep  S.  E.  dipping  rocky  cliffs  on  the  north  bank  of 
the  creek,  the  turnpike  following  the  south  bank.f 

Another  conglomerate  several  thousand  feet  higher  in 
the  series  than  the  last,  and  composed  of  a  few  rather 
massive  layers,  only  20  or  80  feet  thick  in  all,  makes  a  very 
curious  triangular  plate  leaning  against  the  face  of  the  hill 

*But  where  have  we  the  Huronian  and  Cambrian  limestone  intercala- 
tions? Possibly  in  the  Pine  Grove  Furnace  limestone  on  Mountain  creek; 
which,  however,  Pennsylvania  geologists  have  always  referred  to  the  great 
limestone  formation  of  the  Cumberland  valley;  considering  it  a  synclinal 
outlier,  like  the  Saucon,  Oley  and  Downingtown  limestone  outliers  in 
Northampton,  Berks  and  Chester  counties.  If  the  Pine  Grove  limestone  be- 
longs to  the  South  mountain  mass,  it  is  certainly  a  very  extraordinar\-  fact 
that  it  does  not  crop  out  anywhere  else  in  the  South  mountains  except  just 
there  along  Mountain  creek  ;  and  that  it  is  there  accompanied  with  the  same 
decomposed  damourite  limeslates  and  brown  hematite  iron  ores  which 
range  with  the  Cumberland  valley  limestones  from  the  Delaware  to  the 
Potomac  and  far  into  the  Southern  States. 

f  These  were  some  of  the  local  facts  which  persuaded  me  that  the  mount- 
ain backset  at  the  pike  and  creek  had  been  made  by  a  great  cross-fault,  with 
a  throw  of  four  miles. 


GEOLOGY  OF  THE  SOUTH  MOUNTAIN.        149 

on  the  northwest  side  of  the  Conococheague,  four  miles 
north  of  the  turnpike.  The  base  of  the  triangle  is  in  the 
bed  of  the  creek  ;  its  apex  makes  a  little  platform  project- 
ing from  the  side  of  the  wagon  road,  here  more  than  a 
hundred  feet  above  the  creek.  The  outcrop  slopes  slanting 
both  ways  down  to  the  creek,  and  reappears  again  in  low 
bluffs  at  the  mouth  of  a  branch  further  on,  whence  it  can 
be  traced  a  mile  or  two  further  northeast,  ascending  to  the 
higher  land.* 

These  two  instances  prove  the  general  fact  that  these  con- 
glomerate beds  are  not  mere  local  bunchings  of  gravel,  but 
are  widely  extended  gravel  deposits  at  fixed  horizons  in  the 
series,  and  may  therefore  be  used  as  key-rocks  for  working 
out  the  geology  and  perhaps  for  breaking  up  the  series 
into  sub-divisions  which  may  at  some  future  time  receive 
distinctive  names.  But  they  lend  no  help  to  the  notion 
that  they  are  of  Medina  age,  because  they  areinterstratified 
with  a  great  thickness  of  other  beds. 

A  conglomerate  of  coarse  character  and  some  thickness 
makes  a  ridge  with  a  bold  south-facing  cliff  end  in  the 
ravine  issuing  at  Mont  Alto.  The  dips  here  are  vertical, 
and  the  place  of  the  beds  in  the  series  is  undetermined. 
The  locality  is  ten  miles  south  of  the  pike  at  Greenwood  ; 
a  north  and  south  road  connects  the  two,  and  along  this 
road  the  ridge  is  faced  with  jaspery  grey  and  purple  slates, 
quarried  for  road  metal,  f 

*Standing  on  the  apex  of  the  triangle  and  looking  eastward  across  the 
valley  of  the  Conococheague,  one  sees  opposite,  about  half  a  mile  away  and 
at  the  same  height,  the  apex  of  a  similar  triangular  outcrop  of  the  same  con- 
glomerate* beds  dipping  northwest  about  20°.  The  creek  here  flows  in  a 
shallow  synclinal  fold,  as  represented  on  Dr.  Frazer's  Section  No.  11.  The 
exhibition  ol  erosion  is  unusual  and  very  interesting.  The  conglomerate 
soon  turns  over  to  a  southeast  dip,  sinks  into  the  broad  highland  of  S.  E. 
dipping  conglomerate  schists  at  least  5,000'  thick,  past  another  small  syn- 
clinal roll,  to  the  70°  S.  E.  dipping  green  hydro-mica  schists  and  micaceous 
slates  which  introduce  the  orthofelsite  country  from  Newman's  (on  the 
pike)  to  Cashtown  at  the  northwest  edge  of  the  Triasic  plain. 

These  features  of  topography — the  straight  sharp  conglomerate  ridges 
and  gaps,  the  triangular  outcrops  and  iron  mines,  are  exhibited  on  my  map 
of  the  Caledonia  Furnace  lands  (surveyed  by  me  in  1873)  in  the  Atlas  ac- 
companying this  Report 

fSuch  purplish  red  slates  are  an  uncommon  element  in  the  South  mount- 
ain mass,  but  they  have  been  occasionally  observed.  There  is  no  general  ex- 


150  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

The  number  of  these  conglomerate  beds  may  be  exagge- 
rated on  account  of  the  rolling  (anticlinal  and  synclinal) 
structure  of  the  mountain  mass  as  a  whole.  It  is  evident 
that  the  rolls  must  be  more  numerous  than  the  outcrops 
show,  the  surface  being  smoothly  eroded  and  covered  with 
sand.  The  whole  mass  descends  from  northwest  to  south- 
east, but  it  descends  in  a  series  of  rolls,  some  of  which  are 
very  distinct,  but  most  of  them  are  mere  crimples.  It  has 
just  been  said  that  the  Conococheague  north  of  the  pike 
flows  in  a  synclinal  (see  foot-note  on  last  page). 

Section  8  shows  that  Mountain  creek,  at  Pinegrove  Fur- 
nace, flows  in  this  same  synclinal,  of  the  same  shape  and 
size  ;  and  that  the  rocks  turn  over  in  the  same  way  south- 
eastward. Several  other  small  synclinals  occur  on  that  sec- 
tion (if  the  surface  dips  be  properly  correlated),  one  of 
them  tightly  compressed  and  thrown  over  to  the  west. 
There  is  a  rather  grand  synclinal  at  the  eastern  end  of  that 
section. 

Section  9  was  made  along  the  Gettysburg-Shippensburg 
road  over  the  highest  part  of  the  mountain.  It  starts  at  the 
summit  of  the  Mt.  Holly  quartzite  range,  2,100'  above  tide, 
and  runs  S.  E.  nearly  five  miles  to  the  Conewago  creek  4 
miles  from  Arendtsville.  A  mile  from  the  summit,  ap- 
proaching Beamer's  mill  on  Mountain  creek,  the  following 
opposite-dipping  outcrops  of  quartzite  are  encountered  in 
rapid  succession  :  S.  45°  E.,  60°  (two) ;  N.  W.  ? ;  S.  45°  E.. 
50°;  N.  40°  W.  40°;  S.  35°  E.  70°;  N.  35°  W.  55°,  70° 
(two).  How  many  more  such  crimples  are  concealed  under 
the  sand  which  covers  the  mountain  is  not  known*  Then 
follows  a  gap  of  6,575',  the  surface  being  strewn  with  frag- 
ments of  conglomerate  schist  and  quartzite,  but  nothing  ex- 
posed. In  the  last  half  mile  the  schist  becomes  more  and 
more  composed  of  small  quartz  fragments  until  the  rock 
turns  into  a  nearly  perfect  quartzite.  Then  appear  quartzose 
conglomerate  schist  dipping  S.  35°  E.,  45°,  50°  (two  out- 
crops) ;  N.  60°  W.  20°.  A  mile  further  orthofelsite  and 

hibition  of  them  as  in  the  Cambrian  country  of  Vermont  and  eastern  New 
York.  Pink  quartzites  occupy  the  west  end  of  Section  No.  11,  on  the  higli 
ridge  1|  miles  west  of  the  Conococheague  and  2|  miles  N.  20°  E.  of  Cale- 
donia furnace.  (Report  CC,  p.  293. ) 


GEOLOGY   OF   THE    SOUTH    MOUNTAIN.  151 

schist  are  exposed,  dipping  S.  15°  E.  85°  ;  S.  40°  E.  55°. 
These  two  dips  are  evidently  on  the  crest  of  a  sharp  anti- 
clinal roll  of  unknown  quantity. 

The  relationship  ol  the  South  mountain  rocks  to  the  rest 
of  the  Azoic  rocks  of  the  state,  to  the  Highlands,  to  the  Phil- 
adelphia belt,  to  the  York  and  Lancaster  county  gneisses 
and  hydromica  slates,  or  phyllites,  is  certainly  obscure. 
But  their  relationship  to  the  great  Huronian  formations  of 
Canada  and  the  northwestern  states  is  also  an  interestingly 
doubtful  problem,  for  the  discussion  of  which  a  description 
of  the  Huronian  in  its  typical  locality  is  necessary  and  will 
be  given  in  the  next  chapter  for  the  use  of  Pennsylvania 
geologists.  How  the  Huronian  and  Cambrian  are  related 
I  do  not  pretend  to  discuss. 


152  GEOLOGICAL   SURVEY    OF   PENNSYLVANIA. 


CHAPTER  XV. 

The  Huronian  system. 

The  Huronian  system  is  a  vast  series  of  beds  of  gravel 
sand  and  mud  (altered  to  quartzites,  greywackes*  and 
slates),  with  some  beds  of  limestone  and  chert,  and  some 
beds  of  volcanic  ashes  (or  lava  ?  greenstone  trap),  the  whole 
being  traversed  by  trap  dykes,  exhibited  on  the  northern 
shore  of  Lake  Huron  in  upper  Canada. 

Logan's  section  of  1863  f  gives  the  relative  proportions  of 
the  kinds  of  rock,  thus  :  Quartzites.  10,820' ;  Graywackes 
(slate  conglomerates)  4,280';  Chlorite  slates,  epidote  slates, 
and  trap-like  beds,  2,000';  Limestone  and  schist  beds,  900'. 
Total  of  undulating  strata  visible  along  the  north  shore  of 
Lake  Huron,  18,000'. 

But  the  proportion  of  Quartzites  is  even  greater  than  this 
and  amounts  to  at  least  two-thirds  of  the  whole  ;  one-sixth 
consists  of  Graywackes  (slate  conglomerates) ;  one-ninth  of 
Chlorite,  epidote  and  trap  beds ;  one-eighteenth  of  Lime- 
stone and  schist  beds.  In  other  words,  12  :  3 :  2 :  14 

*This  term,  r/raywacke,  greywacke,  grauwacke,  has  almost  disappeared 
from  geological  literature,  but  is  common  in  the  older  books.  Lyell  ex- 
plains it  in  his  Manual  of  Elementary  Geology  ( N.  Y.  reprint  1853,  p.  350)  as 
a  German  miner's  name  for  brecciated  sand  rocks  of  the  Silurian  system, 
composed  of  small  fragments  of  quartz,  flintslate  (Lydian  stone)  and  clay- 
slate  in  a  clay  cement.  Similar  grits  are  found  in  Devonian,  Carboniferous, 
Cretaceous  and  Eocene  ages ;  and  they  are  common  among  Huronian  rocks, 
where  the  cement  is  more  siliceous  and  the  feldspar  fragments  are  in  an  al- 
tered condition  (Irving).  They  are  the  Huronian  "conglomerates"  of  the 
later  literature. 

fGeol.  Canada,  1863,  p.  55,  Atlas  Plate  3.  This  section  has  recently  been 
verified  by  Irving  ;  U.  S.  Geol.  Sur.  5,  Report  4,  1885,  p.  188. 

JMurray  described  the  series  in  his  report  to  Logan  (G.  S.  Can.,  1847-8,  p. 
189)  as  "a  set  of  regularly  stratified  ....  quartz  rocks  (or  altered  sand- 
stones), conglomerates,  slates  and  limestones,  interstratified  with  beds  of 
greenstone."  Under  the  term  slates  he  included  "thinly-laminated,  dark- 
green,  blackish  and  reddish  rocks,  some  ...  very  chloritic  (magnesian) 
and  some  containing  epidote."  Hunt  makes  the  smaller  items  of  the  list 


THE   HURONIAN    SYSTEM.  153 

Thin  sections  under  the  microscope  show  the  quartzites, 
graywackes  and  slates  to  he  sediments  hardened  into  rock 
chiefly  by  the  infiltration  of  siliceous  waters,  the  silica 
being  deposited  so  slowly  between  the  grains  as  to  crystal- 
lize around  them,  so  that  the  shape  of  the  grain  remains 
visible  in  the  interior  of  the  enveloping  crystal  of  quartz.* 

The  chloritic  and  epidotic  slates  which  make  up  so  small 
a  part  of  the  column  have  been  made  by  Dr.  Hunt  the 
basis  of  an  immense  generalization  extending  over  Europe 
and  America.  From  the  typical  locality  of  these  slates, 
just  east  of  Thessalon  Point,  Irving' s  specimens  under 
the  microscope  showed  themselves  to  be  "merely  eruptive 
diabasic  greenstones  in  various  degrees  of  alteration."  The 
false  idea  that  the  Huronian  series  on  Lake  Huron  is  char- 
acteristically chloritic  has  been  partly  generated  by  the  oc- 
currence of  greenish  chloritic  graywackes  in  the  slate  con- 
glomerates, f 

The  alteration  of  the  rocks  on  Lake  Huron  is  not  dif- 
ferent from,  but  only  more  universal  than,  that  of  ac- 
knowledged sedimentary  and  fossiliferous  sandrocks  etc. 

The  basic  traps  are  augitic  in  various  stages  of  alteration, 

too  important  when  he  quotes  Murray's  rocks  as  "a  great  series  of  chloritic 
slates  and  conglomerates,  with  interstratified  greenstones,  quartzites  and 
limestones."  (Azoic  Rocks,  Report  N,  Geol  Sur.  of  Perm.,  p.  70.)  This  puts 
a  false  face  upon  the  whole  formation,  and  raises  great  difficulties  in  the  way 
of  identifying  it  in  other  regions.  Irving  adds  that  a  large  proportion  ol  the 
so-called  slate  conglomerates  is  quartzite,  the  balance  being  gray  wacke  slates 
and  graywacke  conglomerates,  which  he  describes  in  extenso  in  subsequent 
pages  of  his  report  to  the  U.  S.  Geol.  Survey,  5th  Rept.,  1885.  Logan  in- 
cludes various  greenstone  trap  beds  in  his  measured  groups. 

*Irving,  1885,  p.  188.  Also  his  chapter  on  enlargements  of  mineral  frag- 
ments in  certain  detrital  rocks,  in  same  report,  pp.  218,  to  242  with  figures, 
plates  30,  31,  and  wood-cuts  on  pp.  238,  239,  showing  how  the  planes  of  crys- 
tallization in  the  embedded  fragment  are  continued  outwardly  through  the 
encrusting  quartz  crystal  envelope.  He  has  pursued  bis  investigation  with 
tine  results  through  quartzites  of  Potsdam  and  Medina  age,  and  furnished  a 
sufficient  explanation  of  the  process  by  which  the  loose  sand  and  mud  de- 
posits have  been  more  or  less  completely  converted  into  hard,  brittle  sand- 
rocks  and  slates. 

(•Irving's  foot-note  to  page  188.  Irving,  Van  Hise  and  Merriam  made 
their  study  of  the  coast  line  from  Sault  St  Marie  eastward  to  Serpent  river 
bay,  with  Logan's  map,  in  1884,  and  far  enough  inland  to  get  the  whole  of 
Logan's  series,  occupying  the  area  between  St.  Mary's  and  Blind  rivers. 


154  GEOLOGICAL   SURVEY    OF   PENNSYLVANIA. 

hornblende  being  a  secondary  product.  The  bedded  trap 
does  not  differ  from  the  dyke  trap. 

The  strata  are  so  little  inclined,  so  gently  folded,  so  im- 
perfectly metamorphosed,  and  so  different  in  looks  from 
crystalline  schists,  that  the  total  absence  of  fossils  argues 
an  age  without  life;  seeing  that  fossils  are  constantly 
found  in  rocks  no  more  altered  than  these.* 

The  absence  of  red  hematite  ore  beds  from  the  section  of 
typical  Huronian  strata  is  remarkable.  In  spite  of  this 
fact,  however,  it  is  generally  agreed  that  the  great  series  of 
highly-folded  fragmental  slates  and  quartzites,  chert  schists, 
magnetite  schists,  iron  ore  beds,  limestones,  dolomites, 
clayslates,  micaslates  and  greenstone  of  the  Marquette  and 
Menomonee  region  south  of  Lake  Superior  is  merely  the 
geographical  extension  of  those  on  the  north  shore  of  Lake 
Huron. f  The  greenish  schists  at  the  base  of  the  Marquette 
series  may  perhaps  belong  to  the  underlying  system  of 
Laurentian  gneiss. :(:  Beds  of  strange-looking  rocks  may  be 
explained  by  secondary  alteration  of  basic  eruptives,  e.  g., 
hornblende  schists  and  actinolite  schists,  the  graduation  of 
which  into  greenstone  has  been  both  affirmed  and  denied 
and  given  rise  to  the  two  opposite  views,  that  either  both 
nre  sedimentary,  or  both  eruptive.  But  setting  aside  these 
doubtful  elements  of  the  whole  section,  its  main  features 
are  those  of  the  typical  quartzite  Huronian.  § 

*Irving,  p.  189.  A  curious  and  very  different  explanation  of  the  absence 
of  fossils  from  Huronian  rocks  has  been  offered  by  Dr.  Morris  in  the  pro- 
ceedings of  the  Acad.  Nat.  ScL,  Phila.,  April  7,  1885.  Alter  drawing  atten- 
tion to  the  fact  that  the  oldest  known  animals  have  defensive  armour,  but 
no  offensive  weapons,  and  suggesting  that  they  were  descendants  of  un- 
armoured  ancestors,  in  whom  the  appearance  of  predatory  foes  had  devel- 
oped modes  of  self-defense,  i.  e.,  the  secretion  of  shell  structure,  which 
compelled  them  to  exchange  a  free  swimming  life  for  rest  at  the  sea  bottom, 
j  ust  as  afterwards  the  secretion  of  the  internal  skeleton  was  acquired,  he 
assumes  that  the  unarmoured  ancestry  could  leave  no  traces  of  their  exist- 
ence, i.  e.,  no  fossils  in  the  Huronian.  But  no  one  will  dispute  that  life 
commenced  at  some  date  or  other.  Why  not  then  in  post  Huronian  times? 
.  fSee  the  Reports  of  Brooks,  Rominger  and  others,  who  differ  widely  in 
their  arrangement  of  the  series. 

Jlrving,  p.  190. 

§Irving,  pp.  190,  191.  Some  of  the  greenstones  are  evidently  contempo- 
raneous lava  beds  now  regularly  interstratified ;  others  are  as  evidently 
later  lava  dykes.  As  for  the  Marquette  jaspery  iron  ores,  the  earlier  geol- 


THE   HURONIAN   SYSTEM,  155 

Sir  W.  E.  Logan's  description  of  the  Huronian  section 
from  the  survey  of  Mr.  Murray  in  1847,  '48  and  '49,  is  as 
follows  :* 

The  group  consists  of  siliceous  slates  and  slate  con- 
glomerates, holding  pebbles  of  syenite ;  sandstones  some- 
times showing  ripple-marks,  some  of  the  sandstones  pale- 
red  green ;  and  quartzose  conglomerates,  in  which  blood- 
red  jasper  pebbles  become  largely  mingled  with  those  of 
white  quartzite,  and  in  great  mountain  masses  predominate 
over  them  ;  the  series  intersected  and  interstratified  with 
greenstone  trap,  and  computed  to  be  about  10,000  feet 
thick ;  a  copper-bearing  formation,  etc.  To  this  must  be 
added  from  other  descriptions  of  it  its  distinctive  features  : 
Chloritic  schists,  crystalline  limestones  andsulpher-copper 
ores  ;  its  sandstones  all  in  the  condition  of  quartzize,  and  a 
total  absence  of  fossil  forms. 

ogists  saw  in  them  eruptive  outbursts  with  a  flow-lamination  ;  a  view  lately 
revived  by  Whitney  and  Wadsworth.  Most  subsequent  geologists  have 
looked  upon  them  as  iron-silica  sediments.  They  differ  from  all  known 
lavas  in  being  so  nearly  a  pure  silica  ;  and  it  seems  impossible  to  imagine  a 
molten  flow  of  free  silica  in  presence  of  free  oxide  of  iron.  If  they  be  sedi- 
iments,  the  question  arises  whether  they  were  chemical  or  mechanical  sed- 
iments. The  latter  view  finds  its  support  in  the  loose  magnetic  sand  deposits 
on  the  shore  of  the  lower  St.  Lawrence,  of  the  Pacific  coast  and  elsewhere, 
and  in  the  constitution  of  the  magnetite  ore  beds  of  New  Jersey.  (See  also 
J alien's  "Genesis,  etc.,  in  Eng.  and  Min.  Jour.  N.  Y.,  Feb.  2,  1884.)  Irving 
c-annot  accept  the  eruptive  origin  of  the  Marquette  jaspery  ores  because  they 
graduate  from  pure  sediments  into  highly  contorted  and  confused  masses ; 
but  chiefly  because  magnetite  sediments  have  been  discovered  in  the 
Huronian  quartzite  series  in  Wisconsin  and  along  the  northwest  coast  of 
Lake  Superior.  Here  the  Animikie  series  (Huronian)  are  quite  undis- 
turbed and  undoubtedly  sedimentary.  He  agrees  with  N.  H.  Winchell 
that  some  of  the  Animikie  magnetic  ores  occur  in  eruptive  gabbro  lavas, 
in  isolated  masses,  and  also  disseminated  ;  but  they  bear  no  resemblance  to 
the  Huronian  jaspery  ores.  (See  10th  An.  Rt  G.  Sur.  Minnesota,  pp.  88,  83.) 
The  silica  of  much  of  the  jasper  ore  is  purely  crystalline  quartz;  but  much 
of  it  is  amorphous  (chalcedony).  Many  of  the  great  belts  of  ore-bearing 
rocks  of  the  Menomonee  seem  mainly  composed  of  chalcedony,  which 
Irving  thinks  is  an  original  formation,  but  Wadsworth  eruptive.  But  the  oc- 
currence of  huge  angular  jaspery  and  chalcedonic  fragments  in  the  con- 
glomerate beds  overlying  the  Vermillion  Lake  iron  belt  shows  that  the 
jasper  and  chalcedony  beds  existed  in  that  form  before  the  deposits  of  the 
quartzites  overlying  them.  They  may  represent  the  "chert  beds"  in  Logan's 
original  section.  Irving,  p.  193. ) 

*Proc.  Am.  Ass.  Adv.  Science,  Aug.,  1857. 


150  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

Another  description  of  it*  is  more  precise  and  elab- 
orate. By  this  it  would  appear  that  the  beds  first  depos- 
ited were  white  sand,  500  feet  in  thickness  ;  then,  mag- 
nesian  mud,  2,000  feet;  then,  white  sand,  1,000';  gravel, 
sand  and  mud,  1,280';  limestone,  300';  gravel,  sand  and 
mud,  3,000';  red  sand  and  gravel,  2.300';  red  jasper  gravel, 
2,150';  white  sand,  2,970';  limestone,  sand  and  sinter,  400'; 
white  sand,  1,500;  limestone,  200',  and  over  all,  white 
sand  again,  400',  the  whole  amounting  to  18,000  ;  but  this 
includes  a  great  thickness  of  interst ratified  greenstone  trap. 

What  first  attracts  attention  is  the  vast  quantity  of  stuff 
deposited  in  this  ancient  Huronian  lake  or  sea  or  arm  of  the 
ocean,  whatever  it  was ;  18,000  feet  in  all.  a  thickness  of 
strata  equal  to  three  miles  of  vertical  depth.  Secondly,  the 
great  preponderance  in  quantity  of  sand  and  gravel,  15,000 
feet  in  all,  over  the  quantity  of  finer  muds,  2,000  feet,  of 
limestone,  900  feet ;  indicating  the  force  of  the  rivers  which 
brought  the  materials  to  the  shore.  Thirdly,  the  alterna- 
tion of  coarse  and  fine  deposits,  representing,  as  is  sup- 
posed, alternate  risings  and  fallings  of  the  sea  level,  and 
consequent  retreatings  and  advancings  of  the  shore  line ; 
for  gravel  is  reckoned  a  shore  deposit,  sand  and  mud  an  off- 
shore deposit,  and  limestone  a  deep-sea  deposit.  But  we 
have  still  much  to  learn  on  this  subject.  In  any  case,  such 
alternations  bear  witness  to  repeated  and  considerable 
changes  in  geography  during  the  deposit  of  these  18, 000  feet 
of  strata  ;  and  it  behooves  us  to  get  some  probable  explan- 
ation of  the  cause  of  such  changes,  and  some  conception, 
however  imperfect,  of  their  geographical  extent, 

It  is  notable  that  at  least  one-fourth  of  the  whole  18,- 
000  feet  of  strata  is  reputed  to  be  made  up  of  volcanic 
materials.  If  so,  it  is  plain  to  see  that  the  land  and  sea  and 
air  were  greatly  disturbed  -by  fiery  phenomena  on  a  grand 
scale,  producing  frequent  changes  in  the  sea  bottom,  coast 
line  and  drainage  system  of  that  district. 

Probably  then  other  districts  were  subjected  to  similar 
vicissitudes  of  land  and  sea,  each  district  attending  to  its 

*Crystalline  Rocks  of  the  Northwest,   N.  H.   Winchell,  Address  before 
Section  E,  Amer.  Ass.  Ad.  Sci.,  Sept.  4,  1884. 


THE   HURONIAN   SYSTEM.  157 

own  local  and  peculiar  geological  business,  of  a  kind  per- 
haps very  different  from  that  of  the  Huronian  rock  section 
cited  above,  and  yet  contemporaneous. 

It  would  also  follow  that  there  must  have  been  a  uni- 
versal, irregular,  changing  floor  upon  which,  in  many  parts 
of  the  earth's  surface  at  the  same  time,  sediments  local  in 
their  origin,  local  in  their  destination,  and  special  in  their 
nature  were  dumped  into  standing  water,  in  variable  quan- 
tities, at  variable  rates,  under  varying  conditions  and  in  a 
variable  order.  We  know  of  no  such  floor  if  it  be  not  rep- 
resented at  the  present  surface  here  and  there  by  the  areas 
of  hornblendic  granite  and  gneiss  rocks  ;  whether  these  be 
considered  as  the  cooled  and  crystallized  original  crust- 
matter  of  the  globe,  or  whether  they  be  looked  upon  as  most 
ancient  sediments  metamorphosed  or  recrystallized.  Now, 
any  sediments  deposited  upon  the  floor  anywhere  would 
necessarily  lie  unconformably  upon  the  older  gneisses;  and 
therefore  the  first  of  the  three  questions  proposed  above — 
was  there  a  historic  break  between  the  end  of  the  Laurentian 
age  and  the  beginning  of  the  Huronian  age  ? — would  seem 
to  be  answered  in  the  affirmative.  But  the  answer  is 
purely  theoretical  and  does  not  help  us  a  whit,  unless  we 
can  convict  the  lowest  bed  which  shows  itself  in  the  Lake 
Huron  country  of  being  really  and  truly  the  first  and 
bottom  bed  deposited  upon  that  part  of  the  granite  floor. 
Of  this  fact  there  is  up  to  the  present  time  no  proof  ;  nor  is 
it  known  with  an  approach  to  certainty  how  the  Huronian 
strata  lie  upon  the  Laurentian  rocks  ;  nor  whether  the  so- 
called  upper  Laurentian  series,  with  its  limestones,  be  not 
a  continuation  downwards,  or  even  sideways,  of  the  Huron- 
ian strata. 

In  the  midst  of  such  uncertainties  the  term  Huronian 
must  be  used  simply  as  a  proper  and  private  name  for  a 
series  of  rocks  exposed  along  that  part  of  the  northern 
boundary  of  the  United  States.  Should  a  similar  series  ap- 
pear in  some  other  region  and  be  called  Huronian  on  ac- 
count of  the  resemblance,  the  name  would  have  no  time- 
nalue  whatever ;  unless  we  should  imagine  that  in  a  so- 
called  Huronian  age  the  whole  surface  of  the  planet  was 


158  GEOLOGICAL   SURVEY    OF   PENNSYLVANIA. 

stuccoed  with  a  certain  formation  ;  and  received  successive 
coats  of  other  kinds  of  rock  in  after  ages.  And  in  fact  this 
is  a  popular  view,  but  absolutely  false.  For,  ocean  sedi- 
ments depend  for  their  character  upon  the  kind  of  country 
rocks  through  which  the  rivers  flow  which  bring  the  sedi- 
ments down  to  the  sea  coasts.  It  is  impossible  for  the  sed- 
iments of  two  water  basins  to  be  of  the  same  character 
unless  the  geology  of  them  both  should  be  the  same  ;  and 
if  two  such  similarly-situated  water  basins  are  filled  suc- 
cessively, one  after  the  other,  then  the  similarity  of  their 
deposits  cannot  make  them  of  the  same  age. 

In  like  manner  the  most  dissimilar  series  of  formations 
are  known  to  be  of  the  same  age  ;  because  brought  by  dif- 
ferent rivers  or  groups  of  rivers  from  back  countries  of 
quite  different  characters.  What  is  happening  to-day  has 
happened  in  all  ages.  Nothing  could  be  more  unlike  than 
the  deposits  now  forming  along  the  various  ocean  shores, 
and  in  different  lakes  and  inland  seas  ;  yet  they  are  all  of 
one  age.  Even  the  deposits  making  in  one  and  the  same 
basin  radically  differ  ;  as,  for  example,  along  the  northern 
and  the  southern  sides  of  Lake  Ontario ;  and  along  the 
eastern  and  western  sides  of  Lake  Champlain.  It  would 
therefore  seem  a  useless  task  to  seek  for  the  Huronian 
rocks  far  from  their  native  range.  And  in  point  of  fact  the 
task  whenever  attempted  has  been  unsuccessful.  If  Huron- 
ian strata  existed  elsewhere,  it  would  be  around  the  Lau- 
rentian  mass  of  the  Adirondack  mountains  in  northern 
New  York.  But  they  are  not  to  be  found  there.  To  say 
that  they  once  covered  the  granite  and  the  gneiss  of  that 
country,  but  have  been  removed,  would  be  to  beg  the 
question.  It  is  not  to  be  imagined  that  18,000  or  even 
10,000  feet  of  such  rocks  could  be  removed  without  leaving 
a  trace  behind.  The  small  exhibition  of  specular  iron  ore 
and  slate  in  St.  Lawrence  county  cannot  be  accepted  as  an 
equivalent  of  the  Huronian  system  merely  because  it 
underlies  the  Potsdam  sandstone  and  suggests  the  Mar- 
quette  ores;  especially  in  the  'face  of  the  fact  that  Mar- 
quette  iron  ores  are  not  represented  in  the  section  along 
Lake  Huron  ;  nor  do  they  immediately  underlie  the  Pots- 
dam sandstone  on  Lake  Superior. 


THE   HURONIAN   SYSTEM.  lf)9 

Another  region  where  we  should  expect  the  Huronian 
series  to  appear  is  the  region  of  the  Highlands  in  southern 
New  York,  northern  New  Jersey  and  eastern  Pennsyl- 
vania ;  but  they  are  nowhere  to  be  seen  in  their  supposed 
intermediate  position  between  the  Old  gneiss  rocks  arid  the 
overlying  fossiliferous  sediments. 

On  the  eastern  side  of  the  extension  of  this  Highland 
range  through  Massachusetts  and  Vermont  into  Canada 
there  is  a  narrow  belt  of  so-called  Huronian  rocks,  running 
along  through  Halifax,  Marlboro',  Townsend,  Andover, 
Plymouth  and  Stockbridge  counties  in  Vermont,  gradually 
widening  towards  the  Canada  line  and  appearing  on  both 
sides  of  the  central  belt  of  gneiss.*  Another  belt  further 
east  commences  in  Norwich  county  on  the  west  bank  of  the 
Connecticut  river,  widening  and  crossing  to  the  eastern  side 
of  the  river  before  reaching  Canada.  But  there  is  nothing 
to  show  that  these  formations  have  anything  to  do  in  ori- 
gin, time  or  character  with  those  of  Lake  Huron.  "The 
name  Huronian  is  used,"  says  Prof.  Hitchcock,  "-as  a  mat- 
ter of  convenience  to  designate  all  the  various  schists  of 
chlorite  and  argillite  aspect  overlying  the  gneisses,  and  in- 
ferior to  the  Cambrian,  so  far  as  known."  ''In  southern 
New  Hampshire  the  argillite,  quartzose  and  micaceous  di- 
visions predominate  nearly  to  the  exclusion  of  thechloritic 
schists,  which,  with  the  characteristic  dolomite,  is  seen  in 
Raymond  and  Derry.  Steatite  occurs  in  it  at  Francestown 
in  the  ferruginous  slates,  and  in  the  mica  schists  of  Derry." 

The  Green  mountain  Highland  crystalline  rock  range  of 
Vermont  is  extended  into  Canada  under  the  name  of  the 
Mountains  of  Notre  Dame  for  150  miles,  being  30  miles 
wide  at  the  Vermont  line,  12  where  the  St.  Frances  river 
breaks  through  it,  and  12  on  the  river  Chaudiere  ;  rising  to 
heights  of  3,000  feet  above  tide,  and  sinking  south  of  the 
Isle  d' Orleans  beneath  the  sedimentary  strata,  to  rise  again 
250  miles  further  on  as  the  Shickshonk  mountain  range,  60 
miles  long  and  3,000  feet  high,  ending  eastward  at  the  river 

*See  description  of  XIII  sections  crossing  N.  H.  and  Vermont,  by  Prof.  C. 
H.  Hitchcock,  Concord,  N.  H.,  1884,  and  on  page  14. 


1'60  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

St.  Anne  in  the  river  Gaspe  peninsula.*  The  range  is  de- 
scribed asf  made  up  of  clayslates,  micaceous,  talcose  and 
chloritic  schists  (often  with  much  epidote);  interstratified 
iron-bearing  magnesiau  limestones,  soapstones  and  serpen- 
tines ;  quartzites  ;  and  massive  diallagic,  hornblendic,  py- 
roxenic  and  feldspathic  rocks;  with  beds  of  magnetic,  specu- 
lar, titanic  and  chromic  iron  ore,  beds  of  sulphuret  of  cop- 
per and  native  gold. 

Now,  are  these  exceedingly  various  kinds  of  azoic  rocks 
arranged  in  any  constant  order  of  superposition  to  one  an- 
other, and  does  the  order  as  seen  in  Canada  correspond  to 
their  order  in  Vermont,  in  New  York,  in  New  Jersey,  in 
Pennsylvania?  Such  a  fact,  so  essential  to  the  proper 
writing  of  a  history  of  events  in  the  Azoic  age,  has  never 
been  made  out  by  any  geologist.  The  catalogue  of  rocks 
mentioned  above  includes  all  the  principal  kinds  of  pure 
and  mixed  sands,  pure  and  mixed  clays,  pure  and  mixed 
lime-mads,  argillaceous,  siliceous,  calcareous,  magnesian, 
sulphurous,  ferruginous,  cupriferous,  which  might  be  ex- 
pected from  the  drainage  of  any  primeval  region  of  the 
fundamental  earth-crust,  anywhere,  at  any  time,  in  any 
water  basin,  large  or  small ;  subsequently  more  or  less  al- 
tered by  the  influence  of  heat  and  pressure  through  an  in- 
definitely protracted  length  of  time.  For,  it  must  be  kept 
in  mind,  that  these  sediments  lay  originally  miles  beneath 
their  present  level  as  respects  the  present  sea  level,  and 
were  covered  with*a  world  of  later  sedimentary  strata, 
fragments  of  which  remain  to  tell  the  tale  ;  for  example,  a 
piece  of  the  Mohawk  formation  on  the  top  of  Mt.  Eolus  in 
Vermont,  and  some  Niagara  and  Helderburg  strata  in  Bar- 
nardston  on  the  Connecticut  river.  No  structural  geologist 
can  persuade  himself  that  the  Catskill  formation  stopped  at 
the  Hudson  river,  or  that  the  Coal  measures  of  the  Schuylkill 
and  Lehigh  were  not  originally  continuous  with  those  of 
Rhode  Island.  All  the  formations  of  middle  Pennsylvania 
were  therefore  at  one  time  piled  upon  New  England,  which 
involves  the  statement  just  made  that  the  Green  mountain 

*See  Report  E,  page  83. 
fldem,  p.  85. 


THE   HUEONIAN   SYSTEM.  161 

rocks  were  miles  below  their  present  surface,  and  subject  to 
a  constant  temperature  twice  as  great  as  that  of  boiling 
water,  and  a  constant  pressure  of  40,000  pounds  to  the 
square  inch,  a  pressure  growing  lighter  of  course  as  the 
superincumbent  mass  was  gradually  removed  in  course  of 
time  ;  leaving  them  in  their  present  crystalline  condition  ; 
a  condition  therefore  not  to  be  explained  wholly  by  refer- 
ence to  their  creation  in  any  particular  age,  Huronian  or 
otherwise.* 

The  opportunity  for  the  removal  of  the  superimposed 
strata,  and  for  the  erosion  of  a  part  of  the  crystalline  rocks 
themselves,  was  afforded  by  an  upthrust  along  the  whole 
range  from  Reading  in  Pennsylvania  to  the  shore  of  the 
St.  Lawrence,  irregular  in  its  details,  of  unknown  cause 
and  of  unknown  date  ;  producing  a  long  and  narrow  arch, 
the  sides  of  which  were  so  compressed  as  to  complicate  the 
crown  of  the  arch  with  minor  folds,  as  seen  in  the  Durham 
hills  upon  the  Delaware,  in  the  Highlands  of  New  Jersey 
and  New  York  upon  the  Hudson,  and  the  sections  made 
across  Vermont.  The  body  of  the  arch  is  underground  ;  its 
crown,  appearing  at  the  present  surface,  consists  of  the  so- 
called  Older  Gneiss.  On  its  two  flanks  should  appear  the 
upper  members  of  the  crystalline  series.  But  in  point  of 
fact,  along  its  northwestern  side  much  later  strata  lean 
against  the  arch  ;  and  the  various  crystalline  schists  and 
slates,  micaceous  and  magnesian,  the  serpentines  and 
soapstones,  the  talcs  and  chlorites,  the  chrome  and  gold  and 
copper-bearing  rocks,  which  are  called  the  upper  members 
of  the  series,  seem  to  be  confined  to  its  southeastern  flank 
and  are  spread  abroad  through  the  regions  which  lie  in  that 
direction.  With  all  our  efforts  we  cannot  comprehend  it ; 
for  the  true  nature  of  that  first  great  movement  has  been 
almost  entirely  concealed  from  our  inspection,  and  masked 
by  the  consequences  of  other  more  or  less  similar  subse- 
quent derangements  of  the  ancient  state  of  things  along 
the  Atlantic  seaboard.  The  confusion  and  obscurity  which 

*lt  remains  to  be  explained  however  why  the  lowest  Palaeozoic  strata  are 
not  more  and  more  generally  crystalline,  although  subjected  to  part  of  the 
same  load. 
11 


162  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

characterize  the  literature  of  the  geology  of  all  New  Eng- 
land, the  several  states  of  which  have  been  studied  by  emi- 
nent geologists  for  half  a  century,  the  conflict  kept  up 
between  the  advocates  of  the  sedimentary  stratification  and 
the  advocates  of  the  volcanic  or  plutonic  outflow  of  the 
granitic  and  gneissic  rocks,  and  the  irreconcilable  differ- 
ences of  arrangement  of  its  rock  masses  and  rock  belts  as 
well- characterized  formations  in  sequence  of  time,  prove 
how  little  is  yet  known  of  the  geological  history  of  the 
Azoic  age  or  ages  in  America. 

It  cannot  be  wondered  at  then  that  the  difficulties  en- 
countered in  New  England  should  be  felt  with  equal  force 
in  studying  the  azoic  areas  of  New  Jersey  and  Pennsyl- 
vania, and  that  the  geologists  of  these  states  should  refuse 
to  use  the  names  applied  to  New  England  and  Canadian 
rocks  until  their  validity  be  better  shown.  The  application 
of  local  names  to  distant  regions  under  such  circum- 
stances can  only  be  a  delusion  and  a  snare.  In  the  case  of 
unaltered  well-stratified  and  fossil-bearing  deposits  a  name 
can  safely  be  allowed  to  follow  a  geographical  outcrop  to 
any  distance ;  but  even  then,  as  will  be  shown  further  on, 
the  difference  of  character  and  thickness  which  one  and  the 
same  continuous  formation  exhibits  when  traced  for  hun- 
dreds of  miles  makes  the  use  of  the  name  first  given  to  it 
in  one  locality  of  delicate  and  doubtful  propriety  else- 
where, especially  when  the  name  is  intended  to  indicate  the 
special  geological  age  in  which  the  sediment  was  deposited. 

The  supposed  English  equivalents. 

In  1879,  Hicks  read  his  paper  on  a  new  group  of  Pre- 
Cambrian  Rocks  (the  Arvonian)  in  Pembrokeshire,  before 
the  Feb.  5  meeting  of  the  Geological  Society  of  London.* 
This  paper  gave  rise  to  a  controversy  which  has  thus  far 
shown  no  abatement ;  but  on  the  contrary  has  drawn  into 
its  vortex  most  of  the  geologists  on  both  sides  of  the  At- 
lantic ;  so  that  the  peninsular  of  St.  Davids  has  been  the 
typical  battle-ground  between  those  who  multiply  pre-Cam- 

*  Q.  J.  G.  S.  XXXV,  ii,  p.  285-294,  with  a  little  map. 


THE   SUPPOSED   ENGLISH   EQUIVALENTS.  163 

brian  formations  and  those  who  refuse  to  classify  them  on 
account  of  their  obscurity. 

The  Arvon/an  of  Hicks  are  supposed  to  underlie  the 
Pebidian,  which  underlie  the  Cambrian.  They  are  sup- 
posed to  rest  upon  the  Dimetian  (Laurentian)  gneiss ; 
and  therefore  to  be  the  equivalents  of  the  Huronian  in 
America,  and  of  the  HaUeflinta  series  in  Scandinavia  ;  sed- 
imentary beds  ;  the  rock  being  a  "micro- crystalline  mass  of 
quartz  grains  with  some  intersticial  light-gray  substance 
having  but  little  action  on  polarized  light ;  but  the  chief 
peculiarity  consists  in  the  manner  in  which  the  quartz  is 
separated  away  into  nests,  so  as  to  give  that  curious  por- 
phyritic  appearance ;  the  grains  so  compressed  to- 
gether (and  yet  distinctly  fragmentary)  that  all  other 
material  is  removed  and  nests  of  pure  quartz  grains  only 

are  seen  having  a  very  crystalline  appearance ; 

the  darker  material  is  brought  together  and  made  to  fold 
round  the  nests,  so  that  a  banded  or  imperfect  flow- 
structure  is  given  to  the  rock  ....  as  if  an  incipient 
gneiss  was  being  formed,"  etc.  Fragments  of  these  halle- 
flinta  beds  are  said  to  be  found  in  the  Pebidian  measures, 
which  are  therefore  accounted  of  later  age  and  seem  to  rest 
against  the  Arvonian  everywhere  unconformably.*  The 
different  characters  of  the  three  formations  are  thus  stated  : 

Pebidian ;  (a)  micaceous,  talcose  and  chloritic  schists, 
with  slaty  and  massive  green  bands  containing  epidote, 
serpentine,  etc.;f  (b)  tuffs,  indurated  ashy  shales,  breccias, 
silvery  schists,  porcellanites,  conglomerates  and  agglom- 
erates. 

Arvonian;  breccias,  halleflintas  and  quartz-felsites4 

Dimetian;  quartzose  rocks,  granitoid  gneiss,  and  com- 
pact granitoid  rocks  with  bands  of  crystalline  limestone 
(LaurentianT). 

Dr.  Hicks  read  at  the  same  meeting  another  paper  on  the 
pre  Cambrian  (Dimetian,  Arvonian  and  Pebidian)  rocks 

*See  Hicks'  previous  paper  in  the  Q.  J.  G.  S.  XXXIV,  p.  153. 

f  These  correspond  somewhat  to  our  South  Valley  Hill  rocks. 

t  These  are  supposed  by  Hunt  (T.  S.)  to  correspond  to  our  South  mount- 
ain rocks,  in  Adams  county,  soutn  of  the  Chambersburg-Gettysburg  turn- 
pike. See  his  Report  of  Progress  E. 


164  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

in  Caernarvonshire  and  Anglesea  as  a  sequel  to  his  paper 
of  December,  1877,  Q.  J.  G.  S.,  XXXIV,  p.  147)  in  which  he 
describes  his  re-examination  of  the  district  in  company  of 
Prof.  Torrell  of  Stockholm,  Mr.  Tawney  and  Prof.  Hughes 
of  Cambridge,  and  Dr.  T.  Sterry  Hunt  of  Montreal,  and  the 
evidences  they  obtained  of  the  reality  of  the  distinction  and 
order  of  time  ascribed  to  the  three  great  formations.  The 
paper  contains  a  map  of  the  country  from  Holyhead  to  Port- 
madoc,  and  Prof.  T.  G.  Bonney's  description  of  micro- 
scopic rock  sections.* 

Prof.  Bonney,  however,  read  at  the  same  meeting  a  paper 
on  the  Quartz-felsites  of  Caernarvonshire,  in  which  he  de- 
cidedly rejected  on  microscopic  grounds  the  views  of  Dr. 
Hicks  and  Prof.  Hughes  about  their  sedimentary  and  met- 
amorphic  origin,  and  affirmed  that  they  have  the  character- 
istic features  of  fluid  igneous  rocks  (rhyolites],  lavas  of 
Cambrian  age  ;  of  which  he  gives  six  remarkable  pictures 
(pi.  13,  p.  320)  showing  the  internal  flow-structure,  mag- 
nified 50  diameters ;  also  a  cross-section  (with  one  great 
anticlinal  and  one  great  synclinal)  of  (5)  Pebidian  rocks ; 
purple  slates  resting  on  (4)  green  slaty  grits;  on  (3)  grits 
and  conglomerate  beds ;  on  (2)  lower  conglomerates  inter- 
banded  with  green  slates  ;  on  (1)  green  slates  not  less  than 
3,000'  thick,  cut  off  from  the  (supposed  older)  quartz-felsite 
group  by  a  greenstone  dyke. 

*  Q.  J.  G.  S.,  XXXV,  p.  295-308. 


NO.   I.  CHIQUES   SANDSTONE.  165 


CHAPTER  XVI. 

Formation  No.  1 ;  Chiques  sandstone ;  Hellam  quartzite 
of  York  county ;  North  Valley  Hill  sandstone  of  Ches- 
ter county  ;  White  Spot  sandstone  at  Reading  ;  "  P<  ts- 
dam  sandstone"  of  the  Reports  of  Progress;  Upper 
Cambrian  quartzite  of  Walcott ;  Sugarloaf  sandstone  of 
Maryland. 

It  is  best  to  get  rid  of  the  old  name  "Potsdam  sand 
stone"  at  the  outset  of  a  description  of  this  the  long  con- 
sidered oldest  of  our  fossiliferous  formations ;  for  there 
seems  to  be  no  satisfactory  evidence  that  the  proper  Pots- 
dam sandstone  of  the  Canada  Line  and  Lake  Champlain 
extended  as  far  south  as  southern  Pennsylvania  ;  although 
it  seems  to  be  traceable  into  the  northwestern  states.*  It 
is  possible  however  that  the  friable  sandstone  beds  of 
Sand -Ridge  in  Nittany  Valley,  east  of  Bellfonte,  Centre 
county,  may  represent  the  New  York  Potsdam.  They  un- 
derlie the  Chazy  and  Trenton,  as  the  fossils  show  ;  but  they 
have  limestones  beneath  them,  as  the  South  Ore  Mine  bo- 
rings show.f 

Chiques  sandstone  is  not  only  the  oldest  name  for  our 
formation  No.  I,  but  expresses  the  locality  of  its  finest  ex- 
posure, the  great  rock  mass  which  towers  above  the  east 
bank  of  the  Susquehanna,  for  a  mile  above  Columbia,  and 
ends  abruptly  at  the  Haldeman  mansion  and  iron  furnaces, 

*The  identification  was  based  upon  two  facts,  first  that  it  lay  almost  im- 
mediately underneath  the  great  lime&tone  formations  (Calciferous,  Chazy, 
Trenton);  second,  that  it  contained  worm  burrows  (Scolit/ius).  But  curi- 
ously enough  diligent  search  for  Scolithus  at  the  Potsdam  village  outcrops 
have  failed  to  find  it;  whereas  Scolithus  is  very  abundant  in  the  Cambrian 
quartzites,  at  different  horizons,  in  eastern  New  York,  and  in  various  places 
in  Pennsylvania. 

t  E.  V.  d'Invillier's  Report  of  Centre  Co.,  T4,  p.  31.— See  also  Report  T3, 
p.  152,  where  M.  Sanders'  measurements  on  the  Little  Juniata  make  5,400'  of 
upper  limestone  beds,  about  40'  of  sandstone,  and  1,160'  of  lower  limestones, 
bottom  not  reached. 


166  GEOLOGICAL    SURVEY   OF  PENNSYLVANIA. 

where  Chiquesalunga  (Chikiswalunga,  as  Haldem an  spelled 
it)  creek  enters  the  river.* 

Hellam  quartzite  is  a  name  adopted  by  Frazer  in  his"  York 
county  report,  C2,  because  of  the  extensive  spread  of  the 
formation  over  Hellam  township,  where  several  large  quar- 
ries work  it  out,  and  its  characteristic  Scolithus  fossils  are 
exceedingly  abundant  and  admirably  exhibited  in  place. f 

North  Valley  Hill  rock  is  the  popular  name  for  the  for- 
mation in  its  long  outcrop  through  Chester  and  Montgom- 
ery counties,  where  it  edges  the  Welsh  Mountain  region 
and  looks  down  upon  the  narrow  limestone  valley  of  Coates- 
ville,  Downingtown,  Conshohocken  and  Willow  Grove. 

At  the  White  Spot  on  the  mountain  behind  Reading  it 
has  been  famous  since  the  early  settlement  of  the  Great 
Valley.  But  so  far  from  being  an  unique  occurrence,  we 
now  known  from  the  long  and  minute  geological  surveys  of 
Prime  and  d'Invilliers  that  the  formation  spreads  over  the 
whole  range  of  the  Highlands  of  Berks,  Lehigh  and  North - 
hampton  in  discontinuous  outcrops  and  isolated  irregular 
patches,  between  which  the  older  gneisses  show.  It  very 
generally  forms  the  north  slopes  of  the  range,  facing  the 
Great  Valley  :  and  rises  also  in  more  than  one  place  through 
the  limestones  of  the  valley  itself 4 

Primal  sandstone  is  the  name  of  it  always  used  by 
Prof.  Rogers  in  his  Geology  of  Pennsylvania,  1858.  And  it 
would  be  a  good  name  but  for  the  fact  that  it  is  not  an  ordi- 
nary sandstone  but  a  quartzite  ;  and  for  another  fact,  that 
it  seems  to  take  its  place  as  the  last  not  the  first  of  the 
great  quartzites,  being  probably  in  what  Walcott  calls  his 
Upper  or  Potsdam  subdivision  of  the  Cambrian  system. 
There  is  reason  for  believing  that  it  overlies  in  York  and 
Adams  the  upper  strata  of  the  South  Mountain  and  has 

*See  description  and  section  by  H.  D.  Rogers,  in  Geol.  Pa.  1858,  page  193. 
Also  Dr.  Frazer's  Report  03,  plate  4,  page  108,  and  plate  5,  page  112,  from 
photographs  of  the  cliffs. 

fSee  the  figures  in  Prof.  Wanner's  contribution  to  the  Annual  Report  for 
1876,  part . 

|  See  the  Index  sheet  of  the  great  topographical  map  of  the  region  by 
Prime  and  d'Invilliers,  and  the  county  maps  accompanying  Reports  D,  D2 
D3. 


NO.  I.  CHIQUES   SANDSTONE.  167 

nothing  to  do  with  the  great  quartzites  of  the  Mount  Holly 
range  on  the  Cumberland  and  Fayette  side,  except  as  be- 
longing to  the  same  Cambrian  (or  Huronian?)  system.* 

Prof.  Rogers'  lower  primal  slates  are  evidently  Dr. 
Frazer's  phyllites.f 

*In  England  the  "Stiper  Stones"  of  eastern  Wales  represents  our  Chiques 
sandstone;  a  rocky  formation  1,000'  thick,  vitrified  by  trap  eruptions; 
standing  in  picturesque  pillars  and  castle-like  masses  of  white  crystalline 
quartzite  intersected  by  quartz  veins ;  passing  geographically  into  coarse 
grits  and  siliceous  sandstone ;  good  road  metal ;  flagstones  from  a  few  inches 
to  3'  thick,  separated  by  "way-boards"  of  sandy  shale,  or  greenish  white 
unctuous  clay ;  ripple  marked;  showing  casts  of  sea  weeds  (?)  i.  e.  Cruzi- 
ema,  or  Bilobites;  also  vertical  worm-burrows  (Scolithusa  linearis)  some- 
times syphon-shaped  at  the  bottom,  and  with  trumpet-shaped  mouths,  (see 
good  picture  of  a  slab  on  p.  41  of  Murchison's  Siluria,  London,  1859);  also 
the  characteristic  shell  lingula,  in,  over  and  beneath  the  Stiper  Stone  mass. 
The  Stiper  Stone  graduates  downward  into  and  in  fact  forms  the  upper  part 
of  the  Lingula  flag  formation.  (See  columnar  section  on  p.  156  of  Siluria.) 
It  graduates  upward  into  the  Llandeilo  grey  flags,  slightly  micaceous, 
weathering  brown  (alternating  with  schistose  darker  beds)  at  least  3,000' 
thick,  and  quite  conformably  overlying  the  Stiper  Stones  (Siluria,  p.  48,  49). 
The  underlying  Lingula  flag  formation  {Upper  Cambrian  of  Lyell)  is 
roughly  divisible  into  upper,  middle  and  lower ;  the  upper  and  lower  full 
of  fossils,  the  middle  almost  destitute.  (See  Phillips'  Manual,  London, 
1885,  p.  45.)  The  upper  and  middle  together  are  Sedgwick's  Ffestiniog 
group ;  the  lower  is  Salter  and  Hicks'  Menevian  group. 

f  Dr.  Frazer  says  (General  Notes,  etc.,  Proc.  Amer.  Philos.  Soc.,  Dec. 
4,  1885,  page  398)  :  "There  are  no  good  exposures  of  the  Hellam  quartzite 
with  the  slate  below  it  at  any  place  in  York  county  which  I  recall.  On  the 
flank  of  the  South  mountain  the  quartzite  is  very  much  rent  and  crushed 
into  fragments,  while  of  the  small  patch  on  the  map  about  two  miles  west  of 
Case's  ore  bank  (No.  8  on  the  map)  no  accurate  dip  was  recorded.  The 
quartzite,  of  which  a  part  composes  the  "Chikis  mountain,"  exhibits  in- 
deed in  its  numerous  foldings  the  rock  called  by  Rogers  "talcose  slate"  be- 
tween its  two  principal  beds  of  quartzite,  but  not  appreciably  lower  than 
the  latter." 

The  quartzite  mass  seemed  to  Prof.  Rogers  to  be  double  where  it  makes 
the  river  cliffs  a  mile  below  the  mouth  of  the  Codorus.  Here  an  upper 
quartzite  mass  of  beds  "are  underlaid  by  a  tolerably  thick  belt  of  striped 
slates;  this  again  by  a  succession  of  thick  sandstone  (quartzite)  and  slate, 
the  latter  predominating  until  we  reach  the  limestone  at  New  Holland. 
Sometimes  the  slates  clip  slightly  north  from  the  axis  and  sometimes  they 
are  inverted  or  dip  towards  it.  Haifa  mile  above  the  furnace  on  Codorus 
creek  the  compact  white  sandstone  dips  N,  60°."  (Geol.  Pa.,  Vol.  1,  p.  193.) 
But  from  the  above  description  it  is  evident  that  the  "sandstones  and  slates, 
are  not  beneath,  but  above,  the  quartzites,  as  Dr.  Frazer's  map  shows. 


168  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

No.  I  on  the  Susquehanna. 

The  Chiques  quartzite  is  a  very  hard  rock;  of  white  or 
grey  color,  often  pinkish,  brownish  or  blueish ;  almost  al- 
ways crystalline ;  and  so  brittle  that  the  disturbed  strata 
have  a  smashed  and  confused  appearance,  sometimes  leav- 
ing the  spectator  in  doubt  which  way  the  beds  really  strike 
or  dip  at  the  special  point  of  observation,  although  the  run 
of  the  outcrop  as  a  whole  is  marked  by  a  ridge  of  ground 
more  or  less  bold. 

Prof.  Rogers'  description  of  the  Chikis  rock  section  from 
Columbia  up  to  Chikiswalung  creek,-  although  not  quite 
comprehensible  at  one  or  two  points,  will  serve  to  explain 
the  relationship  of  the  exposed  formations.  SeeGeol.  Pa., 
Vol.  2,  page  193. 

From  the  old  railroad  engine  house  in  Columbia  to  the 
furnace  (1,100')  appear  (1)  for  250',  magnesian  limestone 
crystalline,  mottled,  dipping  50°,  S.  S.  E.,  beds  obscured  by 
cleavages  ;  (2)  for  250',  ferruginous  olive  slate  baked  hard, 
cleft  with  oblique  steep  joints  ;  (3)  for  400',  magnesian  lime- 
stone, more  sandy,  crystalline,  cleft,  white  and  mottled. 
These  are  the  lowest  beds  of  the  great  Lower  Silurian  (Or- 
dovician)  limestone  formation  No.  II,  forming  the  valley  of 
York  and  the  plain  of  Lancaster. 

From  the  furnace  to  a  little  north  of  the  second  ravine, 
2,500',  is  a  fine  natural  section  of  "Upper  Primal  Slates." 
apparently  dipping  all  southward  at  say  an  average  of  4o°, 
but  there  is  a  small  compressed  double  fold  at  the  tunnel  ; 
total  thickness  possibly  1,800  feet,  but  probably  much  less, 
judging  by  their  thickness  "in  the  North  Valley  Hill  of 
Lancaster  and  Chester." 

Chiques  Rock  is  the  square  west  end  of  Chestnut  Ridge, 
which  runs  due  east  4|  miles  to  Hempfield  P.  O.  A  fine 
section  of  the  formation  has  been  made  by  the  river,  and  a 
beautiful  anticlinal  arch  is  plainly  seen  at  the  foot  of  din's 
by  the  side  of  the  road.*  But  it  is  not  so  easy  to  make  out 

*Here  a  cave  of  erosion,  of  no  great  depth,  was  inhabited  by  men,  aban- 
doned, filled  up,  and  re-excavated  by  Prof.  S.  S.  Haldeman,  who  was  re- 
warded by  finding  a  multitue  of  human  implements,  etc.  See  his  paper  in 
the  Trans.  Amer.  Philos.  Soc.,  Phila.,  with  many  plates  and  figures. 


NO.    I   ON   THE   SUSQUEHANNA.  169 

the  true  structure  at  the  north  end  where  another  and  col- 
lapsed and  overthrown  anticlinal  was  seen  by  Prof.  Rog- 
ers, *and  only  the  south  half  of  one  by  Dr.  Frazer,  the  north 
leg  being  lost  in  a  fault,  f 

These  primal  slates  are  greatly  altered,  hard,  olive  green 
inside,  weathering  dingy  brown,  excessively  cleft,  dips  de- 
creasing from  80°  to  65°  at  the  contact  with  the  underlying 
quartzite  at  the  second  ravine.:}: 

Here  a  low,  oblique,  irregular  arch  of  quartzite  (500' 
across)  lifts  the  slates ;  with  two  gentle  waves  on  its  south- 
ern side ;  and  its  northern  side  completely  inverted,  so  that 
the  beds  all  dip  southward,  the  arch  being  tightly  com- 
pressed. In  and  under  the  arch  of  quartzite  appears  an 
arch  of  slates.  The  quartzite  beds  only  measure  in  all 
about  25',  the  underlying  slates  say  300'. 

From  the  arch  to  Chikis  creek  is  3,000',  with  three  quartz- 
ite exposures ;  in  the  first  one  the  quartzite,  27'  thick, 
rises  at  60°  (S.) ;  then  the  slates,  300'  thick,  rise  at  50°  (S.); 
then  the  lower  or  main  body  of  quartzite  rises  at  50°  (S.), 
turns  over  sharply  and  descends  again  vertical,  only  20  feet 
of  the  top  beds  of  this  lower  quartzite  appearing  in  the 
arch,  white,  without  joint  or  fracture  or  trace  of  cleavage, 

*See  Geol.  Pa.,  1858,  Vol.  1,  page  193. 

fSee  Report  C3,  1880,  page  108. 

fThe  metamorphistn  of  the  slates  and  quartzites  which  Prof.  Rogers  de- 
scribes falls  far  short  of  that  of  the  newer  and  older  gneisses;  and  this  is  of 
itself  a  guarantee  of  inferior  age.  It  is  however  an  additional  proof,  if  any 
were  required,  that  50,000  feet  of  the  Palaeozoic  formations,  Ordovician,  Silu- 
rian, Devonian,  Carboniferous  and  Permian,  have  been  removed  by  erosion 
from  the  York  and  Lancaster  county  region.  The  center  line  of  the  Dau- 
phin county  coal  basin  is  only  thirty  miles  distant  (N.)  from  Cbickis  Rock. 
The  forward  thrust  of  the  whole  country  shifted  all  the  geological  localities 
out  of  Maryland  into  Pennsylvania.  The  movement  took  place  upon  the 
floor  of  the  gneiss,  after  the  gneiss  floor  had  lost  more  or  less  of  its  own 
mass  by  previous  erosion.  Consequently  it  must  have  already  suffered  some 
metainorphism  by  heat  and  pressure  before  the  quartzite  and  primal  slate 
were  deposited.  The  added  palaeozoic  time,  heat  and  pressure  increased 
the  gneiss  metainorphism. 

The  pressure  and  heat  to  which  Chikis  rock  was  subjected  at  the  close  of 
the  Permian  age  amounted  to  say  50,000  tons  to  the  square  yard  (90,000  Ibs. 
to  the  square  inch),  at  a  temperature  of  more  than  1,000°  Fahrentheit;  600° 
being  the  melting  point  of  lead,  and  4,000°  of  iron.  The  metamorphic  pro- 
cess was  consequently  one  of  slow  baking,  under  enormous  pressure,  in- 
creasing through  all  the  palaeozoic  ages,  reaching  its  maximum  at  the  end. 


170  GEOLOGICAL   SURVEY    OF   PENNSYLVANIA. 

the  bedding  barely  discernable,  but  showing  how  plastic 
it  must  have  been  to  submit  to  such  a  lap  while  retaining 
its  solidity.  The  arch  of  overlying  slates  up  the  hill  sides 
is  pressed  into  a  sharp  crest,  and  is  full  of  cleavage. 

A  third  "grand  waving"  arcli  at  the  north  end  of  the 
rocks  brings  up  the  lower  main  body  of  quartzite,  making 
the  fine  cliffs  back  of  the  Haldeman  mansion.  The  arch 
at  the  road  is  1,000'  across.  Its  top  shows  two  synclinal 
waves.  Its  south  beds  dip  30°  and  then  45°  (S.).  Its  north 
beds  plunge  vertical,  and  probably  bend  back  underground, 
and  rest  their  broken  ends  on  the  sides  of  the  south  dip- 
ping limestones  of  the  valley,  as  seen  just  across  the  creek. 
Here  the  cleavage  plains  dip  steeply  N".  Everywhere  else 
steeply  S.  about  80° 

The  lower  quartzite  (with  intercalated  slate  bands)  can- 
not be  closely  measured,  but  seems  to  be  about  300'. 

Some  of  the  middle  and  lower  quartzite  beds  are  crowded 
with  Scolilhus  Unearis,  which  are  all  nearly  straight,  and 
sometimes  furnished  with  a  little  knob  at  one  end.  This 
knob  is  the  cast  of  the  funnel-shaped  mouth  of  the  worm's 
burrow  ;  the  best  illustration  of  which  is  given  by  Walcott 
on  plate  LXIII  of  his  Monograph  on  the  Olenellus  Fauna 
of  the  Lower  Cambrian,  published  by  the  U.  S.  Geological 
Survey,  in  1891. 

Dr.  Frazer's  general  description  of  it  as  it  exhibits  itself 
two  miles  north  of  Wrightsville ;  in  fragments  on  the  sum- 
mits of  the  range  of  hills  from  York  to  the  Susquehanna  ; 
on  Shunk's  hill  just  south  of  York ;  on  the  Pigeon  hills 
(line  of  York  and  Adams);  in  the  outcrop  three  miles  north 
of  Hanover  Junction  ;  and  on  the  south  flank  of  the  South 
mountains,  especially  in  Adams  county  ;  is  as  follows  :  "a 
very  fine  grained  and  compact  rock,  exhibiting  generally 
heavy  bedding  and  joints  of  cleavage,  the  latter  frequently 
rendering  its  structure  difficult  to  represent,  awing  to  the 
confusion  arising  from  the  surface  planes.  Its  prevailing 
color  is  flesh  red  or  wine  yellow,  but  it  is  sometimes  beau- 
tifully white."  (02,  page  108.) 

An  analysis  of  Chikis  rock,  by  Mr.  McCreath,  shows : 


THE   CHIQUES    RIDGE   FAULT.  171 

silicic  oxide,  97.100;  ferric  oxide,  1.250;  alumina,  1,390; 
lime,  0.179  ;  magnesia,  0.129;  total,  100.148.* 

The  Chiques  Ridge  fault. 

Along  the  north  side  of  the  Chiques  Ridge  runs  the 
south  edge  of  the  great  limestone  formation  (Calciferols 
Ila]  of  the  Lebanon  Valley.  Along  its  south  slope  runs 
a  belt  of  hydromica  slate  3  miles  long;  south  of  which 
again  runs  a  belt  of  the  limestone  under  Columbia  and 
Mountville ;  then  a  belt  of  the  slate  from  Washington 
Manor,  east  northeast,  3  miles ;  then  a  belt  of  limestone ; 
then  the  phyllite  area ;  then  the  gneiss.  The  two  lime- 
stone belts  widen  out  into  the  great  Lancaster  limestone 
plain.  It  is  logical  to  consider  them  synclinal  belts,  sup- 
ported on  the  hydromicas  ;  these  supported  by  the  Chiques 
quartzite ;  this  by  the  phyllite  formation ;  this  by  the 
gneiss  of  the  Tocquan  anticlinal. 

If  then  the  hydromica  belt  first  mentioned  ends  in  a 
point  (east)  against  the  south  side  of  the  quartzite,  and 
does  not  encircle  the  east  end,  nor  appear  on  the  north  side 
of  the  quartzite  belt  (see  Frazer1  s  Lancaster  Co.  map),  the 
natural  explanation  (although  a  very  unsatisfactory  one) 
must  be  got  by  supposing  faults. 

A  fault,  however,  undoubtedly  ranges  along  the  north- 
ern foot  of  the  Chiques  ridge,  between  the  limestone  and 
the  quartzite,  whether  the  quartzite  beds  simply  are  thrown 
steeply  upward  (north)  against  the  fault,  or  are  doubled 
over  and  crowded  back  downward  into  the  fault.  In  the 
former  case  we  have  an  ancient  basset  edge  wall  of  quartz- 

*I  well  remember  my  astonishment,  many  years  ago,  when  my  dear  old 
friend  John  F.  Frazer,  Professor  of  Chemistry  in  the  University  of  Penn- 
sylvania, told  me  that  he  had  just  analyzed  a  specimen  of  Chikis  rock  sent 
to  him  by  our  common  friend,  S.  S.  Haldeman,  and  found  that  it  was  not  at 
all  a  quartzite,  but  a  silicate  of  lime.  I  never  got  an  explanation  of  this  cu- 
rious adventure.  Probably  the  specimen  had  been  changed,  and  was  not 
from  Chikis  rock.  Possibly  there  may  be  beds  in  the  mass  of  the  compo- 
sition of  which  we  are  ignorant.  Dr.  Frazer  adds  that  a  quartzite  from  Geo. 
Keller's  farm,  through  which  magnetite  crystals  are  disseminated,  is  so 
compact  that  its  grains  cannot  be  distinctly  separated  under  a  high  power 
lens;  but  that  small  irregular  patches  of  limonite  intersect  the  mass;  while 
in  polarized  light  separate  systems  of  concentric  colored  rings  mark  each 
original  quartz  fragment.  (02,  page  108.) 


172    .          GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

ite  (facing  north)  now  represented  by  the  long  line  of  fine 
cliffs  against  which  the  river  impinges  at  the  mouth  of  the 
Codorus,  is  deflected  east  along  its  base,  five  miles,  to  the 
mouth  of  the  Chiquesalunga,  and  then  breaks  through  it  to 
Columbia.  The  line  of  the  river  proves  the  fault ;  the  rock 
cliffs  over  the  Haldeman  mansion  exhibit  it. 

Now,  the  slates  along  the  south  flank  of  the  quartzite 
ridge  cross  the  river  just  above  Wrightsville,  edge  the 
south  side  of  the  triangular  quartzite  area  in  Hellam  town- 
ship, turn  the  west  point  of  the  triangle,  and  make  its 
northwest  border  back  to  the  river,  down  the  Codorus  to 
its  mouth. 

The  geographical  proof  that  the  slates  overlie  the  quartz- 
ite is  complete ;  and  establishes  the  correctness  of  Prof. 
Rogers'  upper  primal  slate  formation. 

The  geological  evidence  is  equally  conclusive ;  for  the 
general  dip  in  the  Chiques  rocks  is  southward,  under  the 
slates  ;  and  of  the  slates  southward  under  the  limestone. 

It  is  possible  that  the  slates  do  actually  crop  out  along 
the  north  foot  of  Chiques  rock  ;  for  there  is  a  concealed  in- 
terval of  half  a  mile  between  the  limestone  and  the  quartzite 
along  the  railroad,  although  in  the  bed  of  the  river,  at  very 
low  water,  Dr.  Frazer  says  the  two  can  bejseen  only  say  100 
yards  apart.  But  as  the  dips  are  nearly  vertical,  this  in- 
terval may  mean  nearly  300  feet  of  slate,  even  supposing 
none  of  the  slates  are  swallowed  by  the  fault.* 

There  can  be  no  doubt  about  the  anticlinal  structure  of 
Chiques  ridge  ;  for,  after  running  a  straight  east  course  for 
eight  miles,  and  losing  itself  beneath  the  Lancaster  lime- 

*C3,  page  108.  The  first  quartzite  beds  are  seen  dipping  a  little  E.  of  S., 
nearly  vertical,  for  a  distance  of  about  1,400  feet  down  from  the  creek. 
About  300  feet  further  south  dips  of  44°  (southward)  begin  and  continue200 
feet.  The  next  500  feet  is  a  synclinal  trough  holding  chloritic  and  hydro- 
mica  schists  ( Upper  Primal  slate) ;  the  basin  being  collapsed  and  over- 
thrown, showing  south  dips  of  48°,  34°,  and  then  south  dips  of  70°,  65°. 
The  next  1.600  feet  is  occupied  by  a  broad  anticlinal  (broken  in  on  the  crown) 
with  one  plain  S.  35°  E.  dip  of  50°  (at  700'),  another  N.  65°  W.  dip  of  78° 
(at  1,000'),  another  S.  35°  E,  dip  of  74°  (1,250'),  and  another  S.  30°  E.  dip  of 
76°  (at  1,450.)  Then  descend  the  same  hydro-mica  schists  with  dips  of  S. 
70°  E.  (!)  21°,  S.  23°  E.  60°,  and  S.  35°  E.  50°  (for  200'  to  Henry  Clay  fur- 
nace=U5' of  slates).  Here  an  intercalated  quartzite  of  peculiar  aspect,  S. 
24°  E.  24°.  Then  come  more  hydro-mica  for  800',  and  so  on  down  the  river. 


NO.    I   EAST   OF  THE   LANCASTER   PLAIN.  173 

stone  plain,  it  reappears  seventeen  miles  further  on,  upon 
the  same  due-east  course,  at  Laurel  Hill,  and  begins  to 
spread  around  the  Welsh  mountain  gneiss  region  into 
Chester  and  Berks  counties. 

That  it  underlies  the  Lancaster  limestone  plain  goes  with- 
out saying  ;  but  we  have  visible  testimony  to  the  fact  in  the 
shape  of  two  outcrops  near  Manheim,  4  miles  north  of  Lan- 
caster, of  oval  form,  each  a  ring  of  quartzite  and  slate 
around  a  core  of  gneiss,  and  probably  marking  an  elevated 
point  or  hump  high  enough  to  reach  the  present  surface 
on  the  crest  of  one  of  those  sharp  collapsed  or  overturned 
anticlinal  rolls  which  pervade  the  whole  underground  of  the 
Lancaster  plain. 

No.  I  east  of  the  Lancaster  plain. 

From  Laurel  Hill  one  belt  of  it  extends  along  the  north 
flank  of  the  Welsh  mountains  E.  N.  E.  12  miles  to  the  ex- 
treme east  point  of  the  county,  and  thence  along  the  Berks- 
Chester  county  line,  partly  in  Berks,  partly  in  Chester,  10 
miles  further,  and  is  then,  before  it  reaches  the  Schuylkill, 
covered  by  the  Trias. 

The  other  belt  passes  south  of  the  Welsh  mountain,  and 
occupies  in  Chester  county  much  of  the  surface  of  West 
Cain  and  Sadsbury  townships  ;  with  three  outlying  smaller 
areas  in  West  and  East  Brandywine  and  Wallace.  From 
Sadsbury  a  continuous  belt  of  it  runs  east  northeast  for  25 
miles,  through  Valley,  Cain,  East  Cain,  Uwychlan,  West 
and  East  Whiteland,  Charlestown  and  Tredyffrin  town- 
ships to  the  Schuylkill  river  at  Valley  Forge,  where  it  is 
covered  by  the  Trias. 

This  is  the  well-known  North  Valley  Hill,  bordering  the 
Chester  or  (Downingtown)  limestone  valley  on  the  north. 

In  all  these  outcrops  of  Lancaster  and  Chester  counties 
(except  the  three  outlines  above  mentioned)  the  belt  of 
quartzite  and  slate  runs  between  the  gneiss  and  the  lime- 
stone, overlying  the  gneiss  and  underlying  the  limestone. 
The  reason  of  tlie  exceptional  cases  is  evident ;  erosion  has 
removed  the  limestone  from  the  quartzite  patches,  which 


174  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

are  themselves  only  remnants  of  a  once  universal  outspread 
of  cjuartzite  over  the  gneiss.* 

In  Montgomery  county,  the  North  Valley  Hill  belt  of 
quartzite  undoubtedly  continues  beneath  the  Schuylkill 
valley,  on  the  same  nearly  east  course,  nearly  to  the  Bucks 
county  line  ;  for  we  see  it  issuing  from  beneath  the  south 
edge  of  the  Trias  in  a  series  of  four  anticlinal  spurs,  or  very 
low  hills,  which  sink  diagonally  (E.  S.  E.)  beneath  the 
limestone  of  the  valley,  f  Beyond  the  last  spur  the  belt 
itself  issues  from  beneath  the  Trias  at  Fort  Washington, 
on  the  North  Penn  RR.,  and  runs  on  six  miles  into  More- 
land  township.  Here  it  ends,  spooning  to  a  point  and  then 
sweeping  round  the  east  spoon-point  of  the  limestone  (2  m. 
E.  of  Pinetown)  it  returns  westward  as  the  south  border  of 
the  limestone  to  the  Schuylkill  at  Conshohocken4 

*  Even  in  the  case  of  the  two  uplifts  of  quartzite  at  Manheim,  above-men- 
tioned, they  have  the  shape  of  rings  around  a  nucleus  of  gneiss.  And  in 
one  place,  near  Green  Bank  P.  O.,  4  miles  east  of  Laurel  Hill,  Lancaster 
county,  the  area  of  quartzite  is  broken  through  by  a  surface  patch  of  gneiss. 

f  This  system  of  diagonal  quartzite  anticlinals  separated  by  limestone  syn- 
clinals is  a  most  curious  phenomenon.  Dr.  Frazer  has  shown  that  it  con- 
tinues in  force  along  the  quartzite  belt  of  Chester  county.  It  proves  a 
widespread  pressure  movement  in  a  N.  N.  E.  direction  ;  and  the  movement 
must  be  of  a  late  date  if  we  are  to  explain  by  it  the  astonishing  anticlinal 
and  synclinal  structure  of  the  Trias  country  of  Bucks  "and  Montgomery  dis- 
covered by  Mr.  B.  S.  Lyman  and  exhibited  on  his  forthcoming  geological 
map  of  those  countiea  (Aug.,  1871.) 

J  Here  the  South  Valley  Hill  begins  and  runs  west  into  Lancaster  county. 
We  should  of  course  suppose  that  this  southern  barrier  of  the  synclinal 
limestone  valley  would  be  made  by  the  quartzite.  But  it  is  made  of  hydro- 
mica  slate..  Repeated  reports  have  been  made  during  the  last  fifty  years  of 
the  discovery  of  the  quartzite  ("Potsdam  sandstone")  at  various  points 
along  the  South  Valley  Hill ;  and  no  doubt  specimens  of  quartzite  have  been 
picked  up,  and  even  thin  outcrops  of  thin  quartzite  beds  among  the  slates 
have  been  seen.  But  these  amount  to  nothing.  They  cannot  be  accepted  as 
expressing  with  any  certainty  the  reappearance  of  the  North  Valley  Hill 
belt  on  the  South  Valley  Hill  side  of  the  limestone.  It  looks  as  if  the  North 
Valley  Hill  rocks  descend  against  a  great  fault,  running  along  the  foot  of 
the  South  Valley  Hill  and  are  there  entirely  cut  off  by  it,  probably  thrown  by 
it  (in  company  with  the  lower  limestone  beds)  high  into  the  air  on  the  Del- 
aware side  of  the  fault 

Now  it  is  just  at  Conshohocken  that  the  Schuylkill  river  breaks  out  of  the 
Chester  county  limestone  valley  to  find  its  way  to  the  sea,  viz.,  in  the  short 
interval  between  the  east  end  of  the  hydro-mica  belt  of  the  South  Valley 
Hill  coming  from  the  west,  and  the  west  end  of  the  southern  quartzite  out- 
crop coming  from  the  east.  What  does  this  mean  ?  Surely  it  is  an  added 


NO.    I.  IN   THE   CHESTER  VALLEY.  175 

In  a  previous  chapter  has  been  given  Mr.  C.  E.  Hall's  de- 
scription of  a  belt  of  vertical  quartzites  running  along  the 
south  edge  of  Bear  Ridge  (older  gneiss)  from  near  Jenkin- 
town,  in  Montgomery,  to  near  Morrisville,  in  Bucks,  in  a 
straight  E.  N.  E.  line  about  16  miles  long,  with  adjoining 
outcrops  of  vertical  limestone  beds  (in  Huntingdon  valley). 
Here  the  quartzite  (called  60  years  ago  eurite)  is  a  sort  of 
itacolumite,  although  it  scarcely  at  all  exhibits  the  peculiar 
flexibility  of  the  well-known  Brazilian  stone.  Perhaps  the 
true  relationship  of  these  beds  'to  the  Chiques  qnartzite  of 
the  North  Valley  Hill  will  never  be  quite  satisfactorily 
made  out. 

Rogers'"  Primal  in  the  Chester  Valley. 

Prof.  H.  D.  Rogers  studied  his  "Primal  Series"  very 
carefully,  and  devoted  many  pages  of  his  Final  Report  of 
1858  to  its  description.  He  divided  it  into  three  formations : 
a  middle  sandstone,  with  slates  below  and  slates  above  ; 
but  warns  his  readers  at  the  outset  that  all  three  divisions 
are  not  always  present,  and  that  "in  the  more  southeast- 
ern zones  especially,  the  Primal  Upper  Slate,  and  in  some 
localities  the  Primal  White  Sandstone  would  seem  not  to 
have  been  originally  developed,  or  to  have  been  deposited 
interruptedly.  Even  where  present  the  recognition  of  the 
slates  is  rendered  in  many  cases  very  difficult  from  their 
close  approximation  in  aspect  and  composition  to  the  more 
ancient  metamorphic  schists."  * 

In  the  Willow  Grove-Barren  Hill  outcrop,  east  of  the 
Schuylkill,  it  is  most  metamorphosed,  resembling  a  regu- 
larly bedded  quartzose  felspathic  gneiss,  decidedly  crystal- 
line, but  the  felspar  crystals  not  so  completely  separated 
from  the  quartz  crystals  as  they  are  in  gneiss  or  granite, 
the  silica  being  diifused  through  the  felspathic  mass  with- 
out much  influencing  its  crystallization,  "very  much  as  the 
sand  occurs  in  the  Fontainbleu  carbonate  of  lime."  So 

proof  of  a  great  fault ;  and  of  the  total  difference  of  the  two  formations  ;  and 
of  the  futility  of  all  endeavors  to  discover  a  southerly  synclinal  rise  of  the 
quartzite  along  the  South  Valley  Hill. 

*Geol.  Pa.,  Vol.  I,  page  149. 


176  GEOLOGICAL   SURVEY    OF   PENNSYLVANIA. 

gneissoid  is  the  rock,  however,  that  it  has  been  regarded  as 
a  variety  of  eurite.  It  is  traversed  by  innumerable  joints, 
dividing  it  into  small  rhombs.  Along  this  whole  Barren 
hill  outcrop  this  thin-bedded  altered  sandstone  has  in  its 
upper  part  much  altered  slate  of  a  felspathic  and  talcose 
character.*  But  there  are  no  purely  siliceous  massive*  beds 
to  be  seen,  as  on  the  Susquehanna,  and  therefore  no  real 
quartzite.  The  disappearance  of  the  sandstone  west  of  the 
Schuylkill,  along  the  South  Valley  Hill,  he  ascribes  to  an 
actual  thinning  out.f 

On  the  northern  Montgomery  Co.  outcrop,  between  the 
Pennypack  and  Wissahickon  creeks,  the  principal  mass  is 
an  alternation  of  thin  bluish-grey  sandstone  beds  and  still 
thinner  brownish  sandy  slate  layers  (much  like  the  "older 
primal  slates"  on  the  Susquehanna  above  Columbia)  some- 
times showing  an  incipient  talcose  crystallization  (Gfeol.  Pa., 
p.  154). 

In  the  North  Valley  Hill  west  of  the  Schuylkill  the 
sandstone  beds  and  upper  slates  run  its  whole  length  ;  the 

*  Wherever  talc  is  noted  by  Rogers,  it  is  well  to  read  either  pholerite  or 
damourite;  for  analyses  have  cast  doubt  upon  the  magnesian  character  of 
the  mineral.  This  induced  Dr.  Frazer  to  adopt  Dana's  name  "hydromiea 
slate"  for  these  apparently  talcose  beds. 

f  On  this  southern  Montgomery  Co.  outcrop,  between  the  Schuylkill  and 
Wissahickon,  Prof.  Rogers  divides  the  formation  into  three,  but  places  the 
'  sandstone  on  top,  thus :  The  lowest  or  semiporphyroidal  group,  of  altered 
sandy  slate,  regularly  laminated  (bedded)  alternately  dark  and  light,  so 
thin  as  to  have  many  in  an  inch,  white  earthy  imperfectly  developed  felspar, 
and  dark  earthy  perfectly  developed  hornblende,  with  scattered  concretions 
of  felspar  from  the  size  of  a  pin  to  a  bullet.  Maximum  thickness  at  the 
Schuylkill  300'  (visible  at  Spring  Mill  100').  Next,  imperfect  talcose  and 
micaceous  slate,  wavy,  garnetiferous,  as  at  the  mouth  of  Aramink  creek  op- 
posite Conshohocken.  When  less  altered,  an  impure  sandstone,  holding  im  - 
perfect  mica  and  talc.  Weathers  to  a  greasy  clay  mottled  deep  red  and  bue, 
evidently  the  source  of  the  brown  hematiteore  deposits  of  the  Valley.  Large 
segregated  chunks  of  cherty  quartz  strew  the  ground.  Thickness  about  200'. 
Upper  member,  the  white  sandstone  of  the  Barren  Hill  anticlinal,  thin-bed- 
ded, yellowish  white,  very  compact,  with  imperfect  felspar  crystals  tend- 
ing to  rhombs ;  the  more  solid  layers  seldom  over  two  inches  thick  ;  schis- 
tose bands  of  felspar-quartz,  with  minute  partings  of  mica  and  talc,  holding 
innumerable  specks  of  pure  black  schorl  (tourmaline).  Thickness  35'  to  40'  ; 
toward  Willow  Grove,  100' ;  further  east  at  least  300'  (Geol.  Pa.,  p.  155). 

It  is  hard  to  believe  that  this  represents  the  series  on  the  north  side  of  the 
valley,  which  lies  just  as  close  to  the  northern  area  of  gneiss  as  this  does  to 
the  southern. 


NO.    I   IN  THE   CHESTER   VALLEY.  177 

sandstone  lying  directly  on  the  gneiss ;  the  lower  slates 
wholly  absent ;  the  sandstone  holding  a  certain  quantity 
of  purely  siliceous  beds,  altered  to  quartzite  ;  some  of  the 
beds  showing  needles  of  hornblende  and  a  little  crystal- 
lized talc ;  general  dip  about  70°  to  the  south  conforming 
to  the  dip  of  the  overlying  limestone. 

The  white  sandstone  exhibits  a  remarkable  constancy  of 
character  from  the  Schuylkill  to  the  Susquehanna  ;  some- 
times more  vitrified  with  imperfect  felspar  specks,  partings 
coated  with  talc,  surfaces  embedding  minute  crystals  of 
schorl ;  sometimes  less  vitrified  or  cemented,  more  porous, 
soft,  crumbling,  less  flaggy,  but  still  showing  some  talc  and 
schorl  (tourmaline),  (Geol.  Pa.,  p.  156). 

In  the  North  Valley  Hill  the  gaps  of  the  East  and  West 
Brandy  wine,  and  at  Gap  station,  show  the  beds  to  be  about 
100'  thick,  and  the  overlying  slates  a  little  more  than  100'. 
But  in  the  South  Valley  Hill  no  continuous  outcrop  of  it 
appears,  although  it  rises  vertically  next  the  limestone  at 
the  foot  of  the  hill  near  and  west  of  Coatsville,  projecting 
conspicuously  a  rugged  outcrop  of  beds  in  all  about  30'  or 
40'  thick,  and  of  the  usual  character.* 

The  most  easterly  appearance  of  the  Chiques  sandstone 
in  the  North  Valley  Hill  of  Chester  county  is  a  mile  east 
of  Valley  Forge  at  the  east  point  of  Mount  Sorrow,  where 
it  emerges  ffom  under  the  Trias,  and  where  its  lower  altered 
slates  are  half  a  mile  wide.  The  sandstone  increases  going 
west,  along  Mount  Joy,  to  the  west  point  of  Tredyffrin 
township  (Ayre's  store).  At  the  Diamond  Rock,  where  its 
crevices  hold  fine  rock  crystals,  the  lower  slates  are  seen  on 
its  north  flank  Several  anticlinal  rolls,  closely  folded, 
make  the  summit  and  south  slope  a  broad  outcrop  of  quartz- 
ite beds.  Here  it  is  set  back  northward,  and  a  new  set  of 
waves  begin.  Most  of  it,  however,  has  been  eroded  from 

*  About  \\  miles  east  of  Downingtown  it  was  exposed  in  the  road  gutter 
and  in  a  well,  and  much  decomposed  and  talcose.  Opposite  Spread  Eagle 
and  Paoli,  it  was  struck  in  T.  Biddle's  well,  and  its  fragments  lie  in  the  soil 
at  the  foot  of  the  hill.  (Geol.  Pa.,  p.  166.)  Mr.  Rand  reports  other  such 
exhibitions.  But  it  is  still  a  question  how  far  any  of  them  warrant  their 
identification  with  the  North  Valley  Hill  rock,  as  they  may  be  sandstone 
intercalations  in  the  South  Valley  Hill  slates. 
12 


178  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

the  gneiss,  leaving  only  a  south  dipping  outcrop  going 
down  under  the  limestone.  Between  this  and  Lancaster 
county  its  outcrop  fluctuates  in  breadth,  owing  to  local 
waves,  which,  as  Dr.  Frazer  shows,  run  obliquely  and  pro- 
duce a  toothed  line  of  junction  with  the  gneiss.  Two  or 
three  such  anticlinal  waves  may  be  seen  in  the  Brandywine 
gaps,  although  their  close  compression  makes  all  the  dips 
steep  southeast,  as  shown  in  Prof.  Rogers'  cross  sections.* 

In  the  gap  north  of  Downingtown  the  lower  slate  can 
hardly  be  found  ;  and  the  quartzite  is  so  complicated  as  to 
seem  a  formation  a  thousand  feet  or  more  thick  ;  whereas 
there  are  only  about  100  feet  of  beds.f  Here  the  first  out- 
crop against  the  limestone  shows  perfectly  regular  c[uartz- 
ose  layers  with  thin  partings  of  white  talc  ;  and  in  the  rock 
many  needles  of  schorl,  always  broken  by  the  plastic 
movement  of  the  matrix.:}:  On  the  outcrops  nearer  the 
gneiss  the  rock  becomes  more  altered,  a  granular  quartzite 
holding  specks  of  felspar  and  mica,  a  good  deal  like  a  fine- 
grained white  granite  ;  but  the  schorl  identifies  it.§ 

*Geol.  Pa.,  1858,  page  175.  Fig.  21,  section  from  Diamond  rock  across  the 
Valley  south  of  Paoli.  Fig.  22,  section  north  of  Coatesville,  showing  two 
fine  arches,  one  double  crested.  Fig.  23,  section  north  of  Parkesburg,  show- 
ing one  sharp  roll,  and  north  of  it  a  deep  synclinal  with  its  south  side  beds  ver- 
tical. Thus  the  belt  varies  in  width  from  400  to  1,200  yards.  Sharp  saddles 
of  the  underlying  gneiss  also  present  themselves  at  the  surface,  splitting  the 
belt  lengthwise ;  and  with  the  gneiss  these  saddles  bring  up  the  slates  which 
lie  upon  it  (and  beneath  the  quartzite  beds)  and  so  altered,  crystalline  and 
gneissoid  as  hardly  to  be  distinguished  from  the  gneiss  itself.  East  of  the 
East  Branch  Brandywine  the  upper  and  lower  slates  seem  very  thin;  but 
they  thicken  rapidly  and  steadily  approaching  the  West  Branch  (Coates- 
ville); which  may  help  us  to  understand  how  the  quartzite  of  the  North 
Hill  (50'  thick  at  Diamond  Rock)  is  almost  wanting  in  the  South  Hill, 
while  the  lower  slates,  so  thin  on  the  North  Hill  side  of  the  Valley,  are  so 
very  thick  on  the  South  Hill  side.  Prof.  Rogers  ascribes  this  to  irregular 
deposition  ;  but  I  think  it  must  be  due  to  some  sort  of  pressure  faulting  ;  if 
in  fact  the  formations  be  identical. 

It  is  almost  unnecessary  to  add  that  the  limestone  of  the  Valley  is  crum- 
pled in  the  same  manner  as  the  quartzite  and  slate ;  nor  to  urge  the  import- 
ance of  keeping  in  view  all  this  movement  as  a  wholesome  check  to  any 
theory  of  irregular,  local,  exceptional  deposits. 

f  As  described  by  Keyes  in  his  paper  on  the  Piedmont  country  of  Mary- 
land, quoted  already. 

§  Geology  Pa.,  page  177.  Prof.  Rogers  always  uses  this  old-fashioned 
name  for  black  tourmaline. 


NO.    I   IN   BUCKS   COUNTY.  179 

No.  I  in  Bucks  county. 

That  the  quartzite  of  the  North  Valley  Hill,  and  of  its 
diagonal  comb-teeth  spurs  in  the  valley  east  of  Norristown, 
passes  broadly  beneath  the  great  Trias  formation  of  Bucks 
and  Montgomery,  making  its  descending  floor,  is  proved  by 
its  sudden  re-appearance  at  the  surface  in  Buckingham  town- 
ship, a  few  miles  east  of  Doylestown.  Here  its  outcrop 
makes  a  bold  low  ridge  nearly  4  miles  long,  running  about 
N.  40°  E.  with  a  belt  of  limestone  on  its  northwest  edge. 
The  limestone  belt  extends  10  miles  to  the  Delaware  river 
at  Centre  bridge.  Both  formations  are  brought  to  the  sur- 
face together  by  a  great  fault,  which  will  be  described  here- 
after. As  there  are  at  least  15,000  feet  of  Trias  south  of  the 
fault,  we  are  justified  in  saying  that  the  quartzite  floor, 
which  disappears  beneath  the  Trias  at  Fort  Washington, 
must  slope  down  northward  at  the  rate  of  at  least  1,000  feet 
per  mile,  i.  e.,  on  a  gradient  at  least  10°.  But  as  the  average 
dip  of  the  Trias  beds  hardly  exceeds  5°  (although  very  varia- 
ble, and  hard  to  calculate  by  average)  it  would  follow  that 
a  very  considerable  amount  of  limestone  overlies  the  quartz- 
ite floor  underneath  the  Trias  region.  Mr.  Lyman's  con- 
structive sections  however  will  make  this  interesting  sub- 
ject clearer. 

No.  I  in  the  Highland  range. 

The  quartzite  floor  emerges  from  beneath  the  north  border 
of  the  Trias  in  Springfield  township,  Berks  county,  where 
the  North  Penn  R.  R.  crosses  the  Lehigh  county  line.  It 
rises  upon  the  south  flank  of  the  Highland  gneiss,  and  runs 
thus,  eastward,  for  13  miles  to  the  Delaware  river  at  the 
county  corner,  between  the  gneiss  and  the  synclinal  lime- 
stone belt  across  which  the  river  cuts  at  Durham  furnace. 
The  limestone  belt  spoons  out,  westward,  at  Pleasant  Valley 
P.  O.,  and  the  quartzite  (forking)  surrounds  its  west  end,  and 
puts  another  belt  south  of  the  limestone,  and  between  it  and 
the  gneiss  of  the  Durham  hill. 

In  Northampton  county  the  quartzite  formation  must  be 
very  thin,  for  although  it  undoubtedly  forms  floor  of  the 


180  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

the  numerous  limestone  valleys  between  and  among  the 
Highland  gneiss  hills,  it  makes  little  show  around  their 
edges,  where  it  lifts  its  outcrops  against  the  gneiss.* 

In  Lehigh  county  the  quartzite  crops  out  from  beneath 
the  limestone  and  against  the  gneiss  all  along  the  foot  slope 
from  Saucon  creek  westward  past  and  around  S.  Bethlehem, 
and  along  the  south  bank  of  the  Lehigh  to  the  west  point 
of  the  mountain  two  miles  south  of  Allentown.  f 

In  fact  the  Lehigh  river,  after  passing  Allentown,  turns 
at  a  right  angle  into  a  narrow  synclinal  trough  of  limestone, 
floored  with  quartzite  lying  on  gneiss.  It  is  a  curious 
gateway  between  the  Lehigh  mountain  (gneiss)  on  the  south 
bank,  and  the  low  gneiss  hill  on  the  north  bank. 

Five  miles  southwest  of  this  right  angle  bend  of  the  Le- 
high, and  in  a  line  with  the  Lehigh  mountain,  there  rises  a 
low  hill  of  gneiss  flanked  with  quartzite.  a  fine  section 
through  which  is  made  by  the  Little  Lehigh  creek. 

Another  outcrop  of  quartzite  runs  along  the  foot  of  the 
mountain  past  Emaus  (opposite  the  low  hill  aforesaid, 
and  two  miles  from  it,  with  limestone  between)  for  about 
five  miles.  .  , 

Another  very  short  one  is  noticeable  at  the  foot  of  the 
mountain,  three  miles  E.  S.  E.  of  Alburtis,  and  another  a 
mile  west  of  Alburtis  near  the  county  line.  With  these 
exceptions  little  or  no  quartzite  has  been  reported  in  Le- 
high county. 

But  in  Berks  county  the  quartzite  makes  a  great  show.;}: 

A  continuous  outcrop  of  it  faces  the  range  of  mountains 
overlooking  the  East  Penn  RR.  all  the  way  from  Alburtis 
to  Reading,  25  miles,  ascending  the  vales  between  the 

*For  instance,  at  the  river  bank  3  miles  below  Eastern;  on  the  slopes  4 
miles  east  of  S.  Bethlehem ;  on  the  slopes  2  miles  south  of  Hellertown ;  at 
the  west  end  of  Chestnut  ridge  3  miles  west  of  Easton ;  at  the  west  end  of 
the  strip  of  gneiss  3  miles  northwest  of  Bethlehem  ;  and  around  the  gneiss 
hills  in  the  bend  of  the  river  between  Allentown  and  Bethlehem. 

t  At  one  place  along  this  line  there  is  a  fine  exposure  of  it,  but  only  25  feet 
thick,  dipping  about  30'  N.  and  laying  directly  and  conformably  upon  the 
gneiss.  It  is  an  exhibition  well  worthy  of  serious  attention. 

fThe  mapping  of  Northampton  and  Lehigh  was  done  by  Prof.  Prime,  and 
a  subsequent  revision  of  the  mineralogy  by  Mr.  C.  E.  Hall.  The  mapping 
of  Berks  was  done  by  Mr.  E.  V.  d'Invilliers.  This  may  account  for  the  ap- 
parent greater  show  of  quartzite  in  Berks. 


NO.    I   IN    SOUTHERN   CHESTER   COUNTY.  181 

ridges  and  spreading  over  the  highest  summits.  A  south- 
ern belt  crosses  the  Schuylkill  a  mile  below  Reading,  and 
encircles  the  whole  of  the  Oley  limestone  valley.  Another 
surrounds  the  isolated  little  Dale  Forge  limestone  valley. 
Another  borders  the  limestone  of  Seisholtzville,  on  the  Le- 
high  county  line.  Three  others  border  the  limestone  ex- 
posures at  Treichlersville,  Churchville,  Bechtelsville  and 
New  Berlin,  where  it  emerges  from  the  north  border  of  the 
Trias.  It  is  made  perfectly  certain  by  all  this  that  the 
Chikis  quartzite  formation  once  covered  the  whole  High- 
lands, and  that  it  underlies  now  the  whole  Trias  region 
east  of  the  Schuylkill.  That  it  underlies  the  Trias  west  of 
the  Schuylkill,  in  Berks  and  Lancaster  county,  is  demon- 
monstrated  in  the  same  way  by  a  long  outcrop  of  it,  be- 
ginning 3  miles  southwest  of  Beading,  and  running  west  6 
miles  to  the  Reading  and  Columbia  RR.  at  Fritztown, 
curving  northwest  and  west  around  the  north  flank  of  Mul- 
baugh  hill  (gneiss),  six  miles  further  to  the  Lebanon  line, 
and  so  round  south  to  pass  out  of  sight  under  the  Trias 
south  of  Mulbaugh  hill.  But  it  is  equally  evident  that  the 
quartzite  is  otherwise  entirely  covered  by  the  limestone 
under  the  whole  Lancaster,  Lebanon  and  Dauphin  Trias 
belt. 

Before  going  west  from  Hellam  township,  York  county,  let 
us  see  what  evidence  we  have  that  the  Chikis  quartzite 
once  extended  from  the  line  of  the  Chester  county  valley 
southward  toward  the  Atlantic. 

No.  I  in  southern  Chester  county. 

In  Delaware  county  no  rocks  assignable  to  the  Chikis 
quartzite  have  been  noticed  by  Mr.  Hall;  nor  any  in  south- 
ern Lancaster  by  Dr.  Frazer.  But  in  southern  Chester  Dr. 
Frazer  (certainly  the  best  authority  on  the  subject)  has 
mapped  a  considerable  area  of  the  quartzite  between  two 
belts  of  limestone,  and  between  two  areas  of  gneiss,  extend- 
ing from  the  Pennsylvania  and  Delaware  RR.  south  of  Doe 
Run  P.  O.  eastward,  for  8  miles,  to  a  little  beyond  Red 
Lion — an  area  four  miles  wide  between  the  limestone  belts, 
and  running  out  east  in  a  long  straight  line  along  the  long 


182  GEOLOGICAL   SURVEY   OF  PENNSYLVANIA. 

straight  line  of  the  southern  limestone  belt.  Upland  and 
London  Grove  are  in  the  middle  of  this  area. 

Another  short  narrow  belt  of  quartzite  runs  from  Kennet 
Square  along  the  Baltimore  Central  RR.  west,  along  the 
north  side  of  another  limestone  belt.  A  similar  outcrop 
borders  the  limestone  from  West  Grove  station,  westward, 
for  3  miles.  Another  small  triangular  patch  in  Kennet 
township  has  its  south  point  within  a  mile  of  the  Delaware 
State  line.  Another  more  important  outcrop  surrounds  the 
limestone  on  Broad  Creek  in  London  and  Britain  townships, 
and  passes  over  into  the  State  of  Delaware. 

It  is  evident,  then,  that  if  the  rock  of  these  outliers  be 
rightly  identified,  the  Chickis  quartzite  had  an  unknown 
extension  southward,  as  it  plainly  had  eastward. 

No.  I  in  southern  York  county. 

In  York  county  its  former  southward  extension  is  guar- 
anteed, but  for  a  comparatively  small  distance,  by  one  long 
outcrop  south  of  the  Wrightsville  and  York  limestone  belt, 
and  by  a  great  many  isolated  patches  in  the  country  north 
of  the  phyllite  belt.*  Even  inside  the  phyllite  belt  there  is 
noted  on  the  map  one  spot  of  quartzite  3  miles  S.  W.  of 
Prospect,  in  Lower  Windsor,  4  miles  west  of  the  Susque- 
hanna  ;  and  a  small  group  at  the  Maryland  line  in  the  S. 
W.  corner  of  Manheim,  and  close  to  the  north  edge  of 'the 
gneiss.  The  absence  of  quartzite  exposures  on  the  surface 
of  the  great  Tocquan  gneiss  belt  in  York  and  Lancaster 
counties,  and  in  Delaware,  Philadelphia  and  southern- 
most Montgomery  and  Bucks  counties,  may  be  due  to  com- 
plete erosion ;  or  it  may  be  indicative  of  a  supposible  fact 
that  it  was  only  through  Chester  county  that  the  quartzite 
and  limestone  formations  at  the  beginning  of  the  Palaeo- 
zoic age  were  thickly  deposited  far  southeast  of  the  great 
Palaeozoic  region. 

Rogers'  Primal  sandstone  in  its  North  Valley  Hill  char- 

*  It  is  possible  that  some  of  these  isolated  patches  are  short  outcrops  of  other 
quartzite  beds  intercalated  among  the  hydromica  slates.  But  they  may  be 
sharp  anticlinals  penetrating  the  slates  from  below  upward  high  enough  to 
reach  the  present  surface. 


NO.  1  IN  SOUTHERN  YORK  COUNTY.         183 

acter,  was  recognized  by  Rogers  in  the  Peach  Bottom  lo- 
cality, and  for  four  miles  down  the  Susquehanna  river  into 
Maryland.  He  assigns  its  principal  outcrop  a  thickness  of 
90  feet,  and  sees  in  the  accompanying  slates  the  upper  and 
lower  members  of  his  Primal  Series,  especially  the  lower  or 
South  Valley  Hill  slates  ;  but  as  his  principal  exposure  of 
sandstone  is  in  his  opinion  an  overthrown  compressed 
anticlinal,  some  at  least  of  the  slates  must  fall  into  his 
upper  division.* 

*  I  give  three  very  interesting  paragraphs  on  p.  189  of  hisGeol.  Pa.,  1858, 
verbatim  for  the  readers'  consideration : 

"The  next  belt  of  strata  cut  by  the  river,  and  indicated  on  our  section,  ex- 
tends from  below  Slate  Point  to  the  second  canal-lock  below  the  State  line, 
a  distance  of  about  four  miles.  The  rocks  here  exposed  are  various  forms 
of  mica-slate  and  talcose-slate,  alternating  with  talcose  white  sandstone,  cer- 
tain outcrops  of  which  bear  the  unmistakable  characters  of  the  Primal  white 
sandstone.  One  or  two  outcrops  of  chlorite-slate  occur,  and  occasionally  the 
mica-slate  graduates  towards  a  micaceous  quartzose  gneiss.  Much  of  the 
finer-grained  talcose  slate  is  undistinguishable  from  rock,  so-called,  which 
near  the  Schuylkill,  and  along  the  South  Valley  Hill,  both  east  and  west  of 
it,  and  also  in  the  antichnals  of  the  Montgomery  and  Chester  Limestone 
Valley,  is  seen  in  intimate  alternation  with  the  Primal  white  sandstone. 
Either  from  the  more  frequent  presence  in  this  district  of  the  middle  part 
of  the  Primal  series,  the  White  Sandstone  group,  or  from  a  less  excessive 
degree  of  metamorphism,  the  strata  here  exhibit  a  far  lower  condition  of 
crystalline  change  than  in  some  of  the  tracts  further  N.,  having  fewer  of  the 
features  of  true  micaceous  schists,  and  more  of  the  characters  of  genuine 
sedimentary  sandstone.  Indeed,  at  several  places  between  Slate  Point  and 
the  State  line,  we  meet  with  a  rock  which,  in  its  composition,  lamination, 
colour,  fracture  and  whole  lithological  aspect,  is  absolutely  undistinguisha- 
ble from  the  main  bed  of  the  Primal  white  sandstone,  as  it  is  seen  in  Edge 
Hill  and  other  notorious  localities  of  this  readily  recognized  rock.  One  of 
the  localities  is  just  below  Slate  Point,  the  sandstone  forming,  in  fact,  the 
south  flank  of  the  Slate  Hill,  and  reposing,  regularly  bedded,  immediately 
upon  the  slate  itself,  which  near  the  contact  is  highly  nacreous,  and  in  that 
minutely  wavy  or  crinkled  lamination  which  usually  denotes  a  metamor- 
phism approaching  the  rock  usually  called  Talc-slate. 

"  About  1700  feet  further  down  the  river,  there  is  another  outcrop  of  Primal 
white  sandstone  immediately  north  of  Hough's  Run  at  the  canal  lock.  Here 
the  rock  is  between  90  and  100  feet  thick.  It  dips  at  the  canal  level  45°  to  8., 
30°  E. ;  but  rising  into  the  hill  it  grows  flatter  until  it  becomes  nearly  level, 
as  if  bending  to  form  an  anticlinal  arch ;  indeed,  it  is  difficult  to  resist  the 
conclusion  that  these  two  south-dipping  belts  of  sandstone  are  simply  the 
two  abutments  of  a  wide  fold  or  flexure,  the  northern  flank  of  which  is  in- 
verted into  a  somewat  steeper  south  dip  than  the  southern.  This  view  is 
confirmed  by  the  crushed  and  contorted  condition  of  the  dark  slates  which 
fill  the  space  between  the  outcrops  of  the  sandstone.  It  is  further  confirmed 
by  the  presence  in  this  neighborhood,  both  within  the  supposed  arch  and  at 


184  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

The  southwestern  extension  of  the  Chickis  quartzite 
formation  in  York  and  Adams  counties,  and  into  Maryland, 
is  in  two  lines  :  (1)  by  the  Pigeon  hills  ;  and  (2)  by  the  south 
edge  of  the  South  Mountains. 

No.  I  in  the  Pigeon  hills. 

The  Pigeon  hills  are  a  range  of  high  ground  ranging  N.  E. 
and  S.  W.  through  Jackson  and  Paradise  townships  of 
York,  and  Berwick  township  of  Adams  county,  at  some 
distance  from  and  parallel  to  the  limestone  belt  along  which 
the  York  Short  Line  RR.,  and  its  continuation,  the  Littles- 
town  Branch  RR.,  run.  Between  the  Pigeon  hills  and  the 
limestone  runs  a  continuous  belt  of  hydromica  schist  from 
half  a  mile  to  a  mile  wide.  At  the  foot  of  the  hills,  mark- 
ing their  southern  limit,  is  a  range  of  iron  ore  banks :  S. 
Emig's,  W.  S.  Johnson's,  And.  Mengis,  Mich.  Meyers', 
S.  Roth's,  J.  Roth's,  J.  L.  Miller's,  Geo.  Bechtal's,  O. 
Ferry's,  Ashland  Co.'s.*  The  Sprenkle  ore  is  on  the  slope  of 
the  hills,  where  they  encroach  so  upon  the  limestone  belt 
as  to  reduce  its  breadth  to  a  quarter  of  a  mile.f 

The  Pigeon  hills,  beginning  near  Farmers  P.  O.  8  miles 
W.  S.  W.  of  York,  run  on  about  8  miles  further  into  Adams 
county,  along  the  S.  E.  edge  of  the  Trias.  They  are  a  belt 

Slate  Point  above  it,  of  a  steep  south-dipping  cleavage,  a  feature  quite  usual 
in  the  slaty  rocks  throughout  the  district. 

"At  other  points  further  down  the  river,  especially  between  Rock  Run 
and  the  State  line,  a  material  having  all  the  aspect  of  the  Primal  white  sand- 
stone under  a  more  extreme  condition  of  metamorphism  reappears.  We 
meet  it  again,  though  materially  more  altered  and  crystalline,  about  two-thirds 
of  a  mile  below  the  State  line,  and  here,  as  we  should  expect,  it  is  in  con- 
tact with  a  dark  crystalline  slate,  precisely  such  as  we  find  the  talcoid  slates 
of  the  South  Valley  Hill,  Chester  county,  where,  in  alternation  with  the 
sandstone,  they  are  more  than  usually  metamorphosed.  In  truth,  we  en- 
counter repetitions  more  or  less  frequent  and  distinct  of  this  altered  white 
sandstone  and  its  contiguous  slates  all  the  way  along  the  river  to  the  mouth 
of  the  first  stream  in  Maryland,  more  than  a  mile  and  half  below  the  State 
line.  In  other  words,  we  may  recognize  these  outcrops  of  the  Primal  white 
sandstone  throughout  a  belt  nearly  three  miles  and  a  half  broad,  from  the 
south  flank  of  the  Slate  Point  Hill  to  near  the  crossing  of  the  great  belt  ot 
serpentine." 

*Frazer's  Report  C2,  pages  55,  58,  63. 

t  C2,  page  100.  This  slate  ovqr  the  limestone,  not  between  it  and  the  quartz- 
ite of  the  hill,  dips  S.  60°  E.  78°  ;  the  limestone  under  it  dip  S.  30°  E.  69°. 


NO.    I   ALONG  THE   SOUTH   MOUNTAINS.  185 

of  quartzite  and  slate  ;  the  slate  on  the  southern  flank  be- 
tween the  hills-and  the  York  valley  limestone,  as  at  Colum- 
bia j  the  slate  belt  being  in  fact  traceable  (with  two  or  three 
slight  breaks  where  bridges  of  limestone  cover  the  slates) 
all  the  way  to  Columbia.  Evidently  a  sort  of  anticlinal 
axis  connects  the  Chickis  arches  with  the  Pigeon  hills  :  but 
the  country  is  too  much  crumpled  to  permit  any  geograph- 
ical regularity  to  the  outcrops.  The  slates  are  dark  ;  the 
sandstone  (quartzite)  beds  light  colored  and  of  various  de- 
grees of  fineness  and  compactness.* 

No.  I  along  the  South  mountains. 

No  Chickis  quartzite  is  seen  in  place  along  the  southeast 
foot  of  the  South  mountains  in  York  and  Adams  counties; 
but  great  quantities  of  quartzite  fragments  lie  on  the  sur- 
face of  the  hydro-mica  schists  as  if  the  formation  had  been 
wholly  broken  up  and  disintegrated.  The  belt  of  frag- 
ments runs  along  between  the  Dillsburg  limestone,  marl, 
trap  and  trias  and  the  schists  of  the  mountain  in  York 
county  ;  and  past  Latti more,  Idaville,  Bendersville,Arendts- 
ville,  Cashtown,  and  so  down  south  past  Fairfield,  down 
Tom's  creek  to  the  Maryland  line,  between  the  trap  and 
trias  and  the  mountain. 

In  Maryland  the  same  exhibition  is  continued  ;  but  after 
a  while  hills  of  quartzite  appear,  and  at  last  a  bold  high 
ridge  of  quartzite  called  the  Sugarloaf  mountain,  advanced 
several  miles  in  front  of  the  Cotoctin  mountain  which  is 
the  eastern  ridge  of  the  South  mountain  (Blue  Ridge)  mass 
of  the  Potomac  country. 

The  Sugarloaf  sandstone  (quartzite)  is  described  as  an 
unmistakable  sedimentary  rock.  Under  the  microscope  it 
shows  no  crystallization,  not  even  an  enlargement  of  the 
quartz  grains,  although  its  cement  is  sometimes  silica 
(chalcedony),  sometimes  decomposed  felspar  (kaolin).  No 
new  minerals  have  been  generated  in  it.  It  has  in  fact 
not  suffered  any  appreciable  metamorphism.  The  series 
of  sandstone  beds  (dipping  east)  pass  upward  through  al- 
ternations of  clay  sand  and  sandy  slate,  into  the  overlying 

*H.  D.  Rogers,  Geol.  Pa.,  1858,  p.  195,  197,  condensed. 


186  GEOLOGICAL   SURVEY   OF  PENNSYLVANIA. 

slates  and  schists.  They  seem  to  be  the  same  as  the  sand- 
stone beds  of  the  Cotoctin  mountain  on  the  west  side  of  the 
Frederick  limestone  belt,  brought  up  by  a  great  fault.  To 
the  east  of  Sugarloaf  however  is  the  great  phyllite  country 
of  alternate  belts  of  hydro-mica  and  chlorite  slate ;  and 
these  seem  to  be  of  later  age  than  the  Sugarloaf  sandstone.* 
In  this  opinion  Mr.  Keyes  agrees  with  Dr.  Frazer's  views 
as  expressed  in  his  third  or  Lancaster  county  report,  al- 
though in  his  earlier  York  and  Adams  reports,  and  in  the 
coloration  of  the  York  county  map,  a  broad  distinction  is 
made  between  the  "hydro-mica  schist"  belt  and  the  "chlo- 
rite schist"  belt  to  which  in  later  years  he  applied  the  term 
"phyllite."  It  is  necessary  to  state  the  uncertainties  more 
in  extenso  in  a  following  chapter. 

No.  I  in  middle  Pennsylvania. 

On  the  Little  Juniata  above  the  Tyrone  Forges,  in  Hunt- 
ingdon county,  the  great  Nittany  Valley  faulted  anticlinal 
brings  to  the  surface  the  bottom  beds  of  the  great  limestone 
formation  No.  II.  It  is  the  only  spot  in  Pennsylvania  north 
of  the  South  mountain  range  where  we  can  look  for  the  ap- 
pearance at  the  present  surface  of  the  Chicques  quartzite  or 
the  hydro-mica  slates  above  it ;  and  in  fact,  about  three- 
quarters  of  a  mile  above  Birmingham,  crushed  and  massive 
grey  sandstone  strata  are  exposed  (dipping  35°  S.  E.)  for 
150  yards.  Under  them  red  shales  appear  ;  over  them  alter- 
nations of  sandy  lime  shales  and  limestones.  These  must 
belong  to  Rogers'  Primal  series,  although  they  are  not  met- 
amorphosed, but  only  crushed  a  little  by  the  fold  of  the 
anticlinal  and  the  slip  of  the  great  fault. f 

*  Keyes,  in  Bull.  G.  8.  A.,  II,  306,  320,  and  figured  microscopic  sections  on 
321. 

t  Geol.  Pa.  I,  page  503.  Dr.  R.  M.  S.  Jackson  in  1837  thought  these  Pots- 
dam. C.  E.  Hall  supposed  in  1877  that  he  found  Potsdam  fossils  in  them. 
(Report  T4,  p.  152).  Specimen  2,662  of  the  survey  collections  above  the 
Birmingham  covered  bridge  is  a  white,  compact  fine-grained  sandstone ; 
Specs.  2,653  to  2,656,  are  sandstone ;  Specs.  2,657  to  2,669,  are  a  ferriferous 
sandstone ;  Spec.  2,661,  marked  "Potsdam"  by  C.  E.  Hall,  is  a  hard  grey 
sandstone  got  below  the  bridge  opposite  the  railroad  station  (T4,  p.  365). 
Prof.  Rogers  likened  the  solid  sandstone  beds  to  Medina. 


ON   SCOLITHUS   LINEARIS.  187 


CHAPTER  XVII. 
On  Scolithus  linearis. 

Scolithus  was  for  many  years  accepted  as  the  fossil  trade 
mark  of  the  Potsdam  sandstone,  and  was  supposed  to  stamp 
with  genuineness  any  outcrop,  any  specimen,  in  which  its 
notable  form  could  be  plainly  seen.  It  is  so  prominent  an 
object  on  the  surface  of  the  cracked  stone,  it  is  so  unmistaka- 
bly unlike  other  fossils,  it  seemed  at  first  to  be  so  entirely 
absent  from  the  overlying  Palaeozoic,  Mesozoic  and  Kaino- 
zoic  formations,  that  the  study  of  it  by  Haldeman  in  the 
fallen  fragments  of  Chicques  rock  near  his  home  at  Colum- 
bia, on  the  Susquehanna  river,  and  his  description  of  it,  in 
1840,  as  the  oldest  fossil  in  the  world,  was  hailed  by  geolo- 
gists with  enthusiasm.* 

Of  late  years  the  gravest  doubts  have  been  thrown  upon 
the  plant  character  of  most  of  the  most  ancient  "algae," 

*  See  his  supplement  .to  Monograph  of  Limniades.  Although  he  con- 
structed the  name  from  skolex,  a  worm,  and  lithos,  a  stone,  he  described  it  as 
the  stem  of  a  seaplant,  and  made  it  at  first  a  subgenus,  and  then  a  genus, 
under  Fucoides. — H.  D.  Rogers  mentioned  Haldeman's  fossil  in  his  second 
annual  report,  1837,  as  a.  marine  plant,  and  suggested  the  name  Tubulites, 
which  was  not  adopted. — Hall's  description  of  it  is  that  of  a  plant  .  .  .  "nu- 
merous linear  stems,  often  extending  to  two  or  three  feet  in  length.  Ordi- 
narily .  .  .  like  a  series  of  small  pins  or  pegs  driven  into  the  rock  in  a  some- 
what regular  manner  and  at  uniform  distances.  It  preserves  its  distinctness 
even  when  the  surrounding  rock  is  much  altered  .  .  .  stained  with  oxide  of 
iron,  and  the  rock  cleaves  more  easily  in  that  direction.  (See  Hall's  Pal.  N. 
Y.,  V.  1,  1843,  page  2 ;  figures  on  Plate  1.)  Even  the  famous  fucoid  of  the 
Bird's  eye  limestone  (in  No.  II)  Hall's  Pkytopsis  cellulosum,  and  Phytopsis 
tubulosum,  1846,  is  now  regarded  by  many  as  a  worm  burrow,  in  spite  of  the 
cross  connection  of  its  stems  and  way  in  which  they  sometimes  radiate  from 
a  sort  of  center  in  all  directions  outward,  curving  and  returning  into  each 
other.  But  the  internal  fibrous  structure,  and  the  interlacing  of  the  fibers 
in  mathematical  forms,  represented  in  the  fine  plates  of  Hall's  first  volume, 
seems  to  place  the  organic  (plant)  structure  of  the  Bird's  eye  fossil  beyond 
all  reasonable  doubt.  ( See  Pal.  N.  Y. ,  Vol.  1,  Plate  8,  Plate  9. )  —The  extrava- 
gant conclusions  of  Nathorst,  which  would,  if  accepted,  expunge  seaplants 
from  palseo-botany,  have  produced  a  beneficial  reaction  towards  a  closer 
study  of  these  mysterious  forms. 


188  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

"fucoid"  or  "seaweed"  markings,  and  as  Etheridge  says 
in  his  edition  of  Phillips' Manual,  p.  34,  the  "  term  Fucoids 
must  be  modified  or  almost  expunged  from  our  nomencla- 
ture, because  nine  out  of  ten  of  them  are  not  casts  of  sea- 
plants  but  of  worm  burrows. ' '  *  The  analogy  of  the  present 
lob-worms  on  all  seacoasts  seems  to  be  a  satisfactory  explana- 
tion of  Haldeman's  Scolithus,  which  has  been  found  abun- 
dantly in  the  sandrocks  and  quartzites  at  the  base  of  the 
Palaeozoic  system  from  Canada  to  Georgia,  and  from  Ten- 
nessee to  Wisconsin,  and  similar  or  allied  forms  in  Scotland, 
Ireland,  Wales,  France,  Spain,  Bohemia,  Silesia,  Finland 
and  Scandinavia. 

In  1856  Salter  named  similar  worm  burrows  of  about  the 
same  or  still  greater  age  in  Shropshire,  Arenicolites^  di- 
dymus,  because  they  were  usually  seen  in  pairs,  joined  by 
a  loop  at  the  bottom,  suggesting  the  idea  that  the  worm 
descended  by  one  hole  and  returned  to  the  surface  by  the 
other4 

In  1858  Kinahan  found  in  the  Lower  Cambrian  (Solva 
group)  of  Brayhead,  Ireland,  curved  trumpet-mouthed 
burrow-casts,  made  by  worms  with  tentacles.  He  named 
them  Histioderma  hibernicum.§ 

*Scolithus  linearis  (Hall)  1847,  found  in  Formations  Nos.  I,  II,  III.  Sco- 
lithus verticalis  (Hall)  1852,  in  Medina  SS.  No.  IV  (Pal.  N.  Y.  II.)  Sco- 
lithus canadensis  (Billings)  1862,  in  Potsdam  No.  I  (Pal.  Foss.  I.)  Sco- 
lithus danieloi  ( Tigillites  danieloi  of  Renault)  in  the  Potsdam  of  France 
(Aguidam,  <fec.);  Scolithus  (Tigillites)  defontaines  (Renault)  in  the  Pots- 
dam of  France  (Guichen,  &c.);  Scolithus  (Tigillites)  dufresnoyi  (Renault) 
in  same.  (Thesaurus  Siluricus  of  Bigsby,  p.  31);,  Scolithus  bohemicus  (Bar- 
rande);  Scolithus  cylindricus  (Barrande)  in  Potsdam,  D.  d.  2  of  Bohemia. 
(Thes.  Sil.  p.  197.)  See  Hall's  Pal.  N.  Y.  I.  2. 

fThe  name  Arenicola  carbonaria  was  given  by  Lamarck  to  a  worm  bur- 
row in  the  Wigan  Coal  measures  of  England  as  early  as  1818,  and  this  in- 
duced Salter  to  substitute  Arenicolites  for  Scolithus,  for  Cambrian  forms- 
American  geologists,  however,  continue  to  use  Haldeman's  name,  while 
English  geologists  prefer  Salter's. 

J  Arenicolites  sparsus  (Salter)  was  found  in  the  Longmynd  of  Shrop- 
shire (Thes.  Sil.,  p.  29.)  Arenicolites  uricomiensis,  found  in  the  quartz- 
ites of  the  Wrekin  in  Shropshire,  is  the  oldest  fossil  as  yet  found  in  Great 
Britain  (or  except  the  Eozoon  canadense,  in  the  world)  provided  the  right 
age  has  been  assigned  to  these  quartzites.  (Etheridge.  Phillman,  p.  34.) 

§Thes.  Sil.  30.— Nicholson's  Manual,  142.— Etheridge's  Phillips  Manual, 
34  in  which  it  is  wrongly  given  hibernica. 


ON   8COLITHUS   LINEARIS.  189 

Salter's  Scolecoderma  tuberculata,  1866,  in  the  Trema- 
doc  slates  of  Wales,  is  regarded  by  him  as  the  membra- 
nous tube  of  a  mud  worm.* 

In  the  very  old  Cambrian  rocks  occur  other  forms,  named 
by  Sternberg  in  1833  Chondrites,  the  oldest  forms  of  which 
are  now  regarded  as  the  casts  of  worm  burrows,  f 

D'Orbigny  in  1842  named  a  kind  of  worm  burrow  with 
traces  of  a  tube  lining  Cruziana.  In  the  oldest  Cambrian 
(Lingula  flags)  Salter  found  Cruziana  s&mtiplicata  /  and  in 
the  nearly  as  old  "  Stiper  stones  "  formation  another  species; 
but  the  numerous  forms  of  Cruziana  named  by  geologists 
occur  chiefly  in  the  Caradoc  sandstone  (Trenton  period.):}; 

The  confidence  with  which  ScoiitTius  linearis  was  at  first 
assigned  to  Potsdam  sandstone  is  illustrated  by  W.  B. 
Rogers'  paper  on  the  Gravel  and  Cobble  stone  deposits  of 
Virginia,  in  which  he  describes  finding,  in  1842,  a  large  peb- 
ble of  compact  vitreous  sandstone  in  a  pile  of  paving  stones  in 
Richmond,  arid  opines  without  doubt  that  the  pebble  had 
come  from  the  nearest  outcrop  of  Potsdam  on  the  west  flank 
of  the  Blue  Ridge.  Subsequently  the  cobble  stone  deposit  of 
Richmond  was  discovered  at  Washington,  and  multitudes 
of  Scolithus  and  other  Palaeozoic  fossils  were  seen  in  it. 
Here  it  consisted  of  two  gravels  of  very  different  ages,  one 
subcretaceous,  the  other  post- tertiary,  both  giving  Scoli- 
thus,  &c.§ 

*  He  found  a  similar  form,  which  he  did  not  name,  in  the  Caradoc.  Hal  de- 
man's  Scolithus  chordaria,  1847,  from  Silesia,  is  put  into  the  category  of 
worm  fossils  by  Bigsby. 

t<7.  acutiangulus,  McCoy,  in  Lingula  flags;  C.  antiquus  and  informis, 
Sternb.  in  Livonia  ;  C.  regularis,  Harkness,  in  Llandeilo  rock  ;  C.  tener  and 
tribulus,  Eichw.  in  Finland  and  Esthonia ;  C.  ?,  Salter,  in  N.  Wales.— But 
Brogniart's  C.  antiquus  was  found  in  the  uppermost  Silurian  (Ludlow) 
beds.  (Thes.  Sil.  p.  29.)— The  Devonian  forms  of  Chondrites  (andrea, 
antiqua,  major, minor, lineata,foliosa,  nessigii,  tceniola)  are  all  placed  among 
plants  by  Bigsby  in  Thes.  Der.  Carb.  1878,  p.  2. 

tC.  bronni,  C.  cordieri,  C.  furcifera,  C.  goldfussi.  C.  lyelli,  C.  prevosti, 
C.  st.  hilaire  (all  of  Rouault) ;  C.  carpetana,  C.  murchisoni,  C.  torrubice,  C. 
Ximenezii  (all  of  DePrado)  ;  C.  rugoso  (D'Orb)  ;  C.  harlani  (Hall);  &c. 
(Thes.  Sil.  p.  30). 

§Proc.  Boat.  S.  N.  H.  1875  ;  reprinted  in  Geology  of  the  Virginias,  1884,  pp. 
709-913.  See  more  of  this  under  Wealden  and  Glacial  ages.— Prof.  Heilprin 
exhibited  a  pebble  containing  Scolithus  linearis  found  in  the  Yellow  Sand 
formation  of  New  Jersey,  near  Glassboro'.  (Proc.  Acad.  Sc.  Phila.,  May  5, 
1885  ;  and  Amer.  Nat.,  Sep.,  1885,  page  928.) 


190  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

It  would  be  strange  indeed  if  worm  burrows  should  be 
confined  to  one  geological  age,  and  still  more  strange — to 
one  petty  formation.  Nor  are  they ;  for  they  have  been 
found  in  sandstone  strata  of  all  ages  ;  and  their  essential 
identity  with  the  ScolUJius  linear  is  of  the  Chiques  (Hal- 
lam)  quartzite  is  now  generally  recognized.  Worms  of 
different  species  have  different  habits,  and  their  burrows 
differ;  but  the  generic  resemblance  remains.  Thus  Sco- 
lithus  is  common  in  the  Portage  formation  '( VIII f}  in 
Bradford  and  Tioga  counties,  and  in  western  New  York.* 
It  has  been  seen  also  in  some  of  the  Coal  Measure  sand- 
stones, in  America  and  in  England.  But  it  is  everywhere 
abundant  in  the  Cambrian  quartzites  of  all  the  American 
Cambrian  regions.  Whether  Dr.  Walcott  is  right  or  not 
in  carrying  the  Cambrian  system  so  high  as  not  only  to  in- 
clude the  Potsdam  sandstone  of  New  York,  but  also  the 
lower  part  of  the  Calciferous  sandstone,  some  of  the  Cal- 
ciferous  beds  are  full  of  8colit7ius.\ 

I  have  devoted  an  entire  chapter  to  this  fossil  form,  be- 
cause the  identification  of  Chiques  rock  with  the  Potsdam 
sandstone  of  the  St.  Lawrence  and  Champlain  country  has 
been  hinged  upon  it,  to  the  confusion  of  our  earlier  Palae- 
ozoic geology  in  Pennsylvania.  It  has  of  course  raised  the 
question  why  all  the  well-known  fossil  forms  of  the  Pots- 
dam were  not  discoverable  on  the  Susquehanna.  No  other 
fossil  but  scolitJius  has  been  seen  in  the  Chiques  rock.  Ob- 
scure shell-like  forms  have  indeed  been  seen  by  Prof.  Warn 

*H.  D.  Rogers,  Geol.  ot  Penna,,  1858,  Vol.  I,  page  296.  "In  the  higher 
part  of  the  formation  some  of  the  layers  contain  a  vertical  fucoid,  if  it  can 
be  so  termed,  a  simple  stem-like  form,  crossing  the  plane  of  the  bedding. 
This  is  evidently  a  species  of  Scolithus,  and  except  that  it  is  a  little  less  regu- 
larly cylindrical,  resembles  greatly  the  species  so  characteristic  of  the  Primal 
andstone." 

f  Brainard  and  Seeley  who  sub-divide  the  1,800  feet  of  Vermont  Calcifer- 
ous  into  five  stages,  say  that  Scolithus  does  not  characterize  any  single  one 
of  the  five,  but  appears  abundantly  in  various  horizons  of  D ;  the  most 
abundant  display  of  it  seen  by  them  being,  however,  at  the  bottom  of  C, 
600'  or  800'  above  the  top  of  the  Potsdam ;  and  yet  pure  limestone  beds  are 
plentiful  in  B.  (Bull.  Geol.  Soc.  Amer.,  Vol.  I,  1890,  p.  510.  See  p.  4,  Diet 
Foss.,  1889,  Vol.  a,  page  943.) — This  should  teach  us  to  look  for  sandstone 
beds  in  the  body  of  our  great  Valley  limestone  formation  ;  and  such  are 
found. 


ON   SCOLITHUS   LINEARIS.  191 

ner  in  the  Hellam  quarries,  but  none  plainly  enough  to  re- 
cognize. Probably  they  are  Cambrian  fossils  ;  for  the  Cam- 
brian rocks  have  furnished  a  plentiful  supply.*  It  was 
indeed  the  age  of  worms,  as  in  an  insect  sense  the  age  of 
coal  was  also  the  age  of  Cockroaches ;  but  a  solitary  cock- 
roach wing  has  recently  been  found  in  France  in  a  sand- 
stone of  Silurian  age.  So,  the  Devonian  age  was  one  of 
great  armoured  fishes;  but  fishes  of  that  order  have  re- 
cently been  fonnd  in  Trenton  rocks.  The  age  of  worms 
now  appears  to  have  swarmed  with  living  creatures  of  both 
lower  and  higher  grades.  It  is  impossible  to  believe  that 
where  the  Hellam  worm-burrows  are  in  millions,  no  other 
fossil  forms  can  be  discovered.  It  only  requires  sharp  self - 
trained  eyesight  to  discover  them.  The  South  mountains 
of  Pennsylvania  will  probably  prove  to  be  a  good  collect- 
ing ground  for  students  of  palaeontology;  and  perhaps  even 
the  semi- crystalline  region  of  the  Philadelphia  belt. 

*Even  in  1886,  Walcott  had  defined  393  species  (92  genera)  of  Algae  (9), 
Spongue  (13),  Hydrozoa  (5),  Crinoidea  (3),  Annelida  (5),  Brachiopoda  (67), 
Lamellibranchiata  (1),  Gasteropoda  (29),  Pteropoda  (20),  Crustacea  (15), 
and  Poecilopoda  (226).  Of  these,  76  (32  genera)  were  found  in  the  Lower ; 
107  (43)  in  the  middle ;  213  (52)  in  the  Upper  Cambrians ;  14  genera  were 
common  to  the  Lower  and  Middle,  15  common  to  the  Middle  and  Upper,  11 
common  to  the  Lower,  Middle  and  Upper,  and  12  common  to  Lower  and 
Upper  (Am.  Jour.  Sci.,  Aug.  1886,  page  149.)  But  this  arrangement  has 
been  exchanged  by  him  for  another  quite  different  (based  upon  his  later 
discovery  of  the  subordination  of  the  Middle  to  the  Lower,  or  of  the  Ole- 
nellus  fauna  to  the  Paradoxides)  in  his  Monograph  on  the  Cambrian  re- 
cently published  by  the  U.  S.  Geol.  Survey,  1891. 


192  GEOLOGICAL   SURVEY    OF   PENNSYLVANIA. 


CHAPTER  XVIII. 
On  Cambrian  fossil  life  'as  known. 

The  great  thickness  of  the  Cambrian  system  may  be 
judged  from  the  fact  that  Walcott  assigns  to  the  Lower 
division  of  it  (the  Olenellus  zone)  in  the  two  eastern  coun- 
ties of  New  York,  Washington  and  Rensselaer  (the  nearest 
Cambrian  region  to  Pennsylvania  as  yet  studied)  a  pos- 
sible thickness  of  14,000  feet  ;*  and  to  the  Middle  and 
Upper  divisions  of  it  (Paradoxides  and  Orihis  zones]  an  ad- 
ditional 2,000  feet.f  But  in  eastern  Massachusetts,  New- 
foundland, Georgia  and  the  Rocky  mountains,  the  Cam- 
brian would  have  a  different  thickness  as  a  whole,  and  dif- 
ferent thicknesses  of  its  three  palseontological  sub-di- 
visions.^: The  fossil  zones  are  no  guides  for  us  in  the  South 
mountains  (if  the  rocks  there  be  Cambrian)  because  none  of 
the  Cambrian  fossils  has  as  yet  been  found  there,  or  indeed 
anywhere  in  the  state.  § 

The  abundance  of  marine  vegetation  and  animal  life  in 
the  Cambrian  age  was  long  ago  inferred  from  the  copious 
life  of  the  immediately  following  Lower  Silurian  (Ordo- 
vician)  age.  It  began  to  be  proved  by  discoveries  in  Bo- 
hemia, Sweden,  Wales,  New  Brunswick  and  Massachusetts. 

*Amer.  Jour.  Sci.,  Vol.  35,  1888,  page  242. 

tThe  sub-division  is  not  made  on  the  basis  of  stone  character,  but  on  the 
stages  of  groups  of  fossils.  He  says:  "About  2,000  feet  below  the  summit  of 
the  strata  assigned  to  the  Cambrian  the  fauna  contains  Olenellus  asa- 
p/ioides,"  <fec.  The  Fauna  of  the  Lower  Cambrian,  in  Tenth  An.  Rt.  U.  S. 
Geol.  Sur.,  Washington,  1891,  page  583. 

Jin  both  the  "Eureka"  and  "Highland"  sections  the  Olenellus  zone  is 
comparatively  narrow.  In  British  Columbia  it  lies  at  the  base  of  the  Castle 
mountain  limestone,  and  beneath  it  are  10,000  feet  (estimated)  of  dark  clay-" 
slates  and  sandstones  (Pre-Cambrian  or  Algonkian)  as  in  the  Wasatch 
mountain  section.  Walcott,  in  U.  S.  G.  S.,  Annual  Rt.  X,  1891,  p.  585. 

§Except  Scolithus,  and  Prof.  Wanner's  undetermined  shell  forms  in  the 
York  county  quarries,  and  perhaps  the  ribbon  plants  of  the  Peach  Bottom 
roofing  slates. 


CAMBRIAN   FOSSIL   LIFE.  193 

It  is  now  magnificently  illustrated  by  Walcott' sand  Ford's 
collections  in  Vermont  and  New  York,  and  by  Walcott' s 
and  Dawson's  collections  in  the  Rocky  mountains.  Other 
geologists  have  contributed  their  several  discoveries ;  so 
that  Walcott' s  latest  list  (1891)  includes  51  genera,  141 
species,  and  11  varieties.  See  Monograph,  page  576. 

Cambrian  fossils  are  wholly  of  marine  forms.  No  traces 
of  land  plants  or  land  animals  have  been  seen  in  Cambrian 
rocks. 

True  Seaweeds  (algce)  have  not  been  certainly  seen,  al- 
though it  is  impossible  not  to  believe  in  their  existence. 
The  so-called  seaweeds  (even  the  Cruziana)  appear  to  be 
trails  of  worms  or  of  shellfish  (mollusks).*  Sponges  were 
very  abundant. f  Jellyfishes  (Medusce)  seem  to  have  lived 
even  in  Lower  Cambrian  times,  and  traces  of  their  soft 
forms  are  recognized  on  the  clayslates  and  fine  sandstones 
of  Sweden  and  on  the  Upper  Cambrian  rocks  of  Alabama.:}: 
Even  the  modern  Sea-sludge  or  Whale-food  order  of 
creatures  were  represen ted. §  Graptolites  also,  those  curious 
and  prolific  leaf-shaped  animals  of  Silurian  times  floated 
on  the  surface  of  the  Cambrian  waters.!  Corals  (Actin- 

*Matthew  however  has  described  what  he  believes  to  be  true  seaweeds, 
from  the  St.  John,  N.  B.,  rocks,  under  the  names  Buthotrephis  antiqua, 
PhycoideMa  stichidifera,  Palceochorda  setacea,  Hydrocytium  (?)  silicula, 
and  Microphycus  catenatus.  On  Cambrian  Organisms  in  Acadia,  Trans. 
Roy.  Soc.  Canada,  VII,  1890,  p.  144.  Compare  the  fossil  plant-like  forms  of 
the  Peach  Bottom  slate  quarries  in  York  Co.,  Pa.,  said  by  James  Hall  to  re- 
semble a  Butrotrephis  of  the  Hudson  river  formation  (No.  IV)  more  than 
anything  else. 

f  Protospongia  is  found  in  the  upper  beds  of  the  Olenellus  zone  and  also 
in  the  Middle  Cambrian  of  our  east  and  west,  and  in  Wales  and  Sweden. 
Leptomitus  is  wholly  Lower  Cambrian.  There  are  two  other  genera.  Wal- 
cott, page  587. 

{The  Swedish  geologist,  Nathorst,  thinks  that  the  once  supposed  seaweed 
Eophyton  is  the  cast  of  the  trail  of  a  jellyfish  moving  over  the  sea-bed.  Pos- 
sibly Dactyloides  aster  aides,  an  American  species,  may  be  so  explained.  It 
is  very  remarkable  that  nothing  like  a  Medusa  has  been  found  in  the  Palae- 
ozoic and  Mesozoic  rocks,  nor  until  we  ascend  to  the  Upper  Jurassic  litho- 
,  graphic  slate.  Walcott,  p.  587. 

§  Matthew  describes  Monadites  globulosis,  M.  pyriformis,  M.  urceifor- 
mis  and  Radiolites  ovalis.  Camb.  Org.  Acadia,  1890. 

||  At  least  two  kinds,  Phyllograptus  and  Climacograptus.  Matthew  has 
assigned  two  Middle  Cambrian  forms  to  the  genera  Dendograptus  and  Pro- 
tograptus. 

13 


194  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

ozoa)  had  hardly  begun  to  appear.*  Sea  urchins  existed 
early  and  became  numerous  in  the  Middle  Cambrian,  f 
Worms  were  infinitely  numerous,  swarming,  trailing  and 
burrowing  over  and  in  the  sea  bed  and  shore  sands,  from 
the  beginning  to  the  end  of  Cambrian  times,  and  under- 
going no  change  so  far  as  the  casts  of  their  tracks  and  bur- 
rows can  teach  us  anything  of  their  character.  They  have 
been  grouped  in  four  genera :  Planolites,  Hilminthoi- 
dichnites  (lobworm  tracks),  ScolitTius  and  Oruziana. 

The  BracJiiopod  shell  life  of  Cambrian  times  was  abund- 
ant ;  ten  genera  (and  29  species)  are  known  in  the  Lower 
Cambrian  (Olenellus),  zone,  viz.,  Lingulella,  Acroleta, 
Acrothele,  Iphidea,  Kutorgina,  Linnarssonia^  Obolella, 
Ortkis,  Orthisina,  and  Camarella.%  These  have  no  special 
embryonic  traits  of  character  in  the  Darwinian  sense,  lead- 
ing to  higher  development  in  the  Middle  and  Upper  zones  ; 
but  after  that,  in  Lower  and  Upper  Silurian  times,  the 
superior  articulated  families  (Orthidse  and  Rhynchonel- 
lidse)  predominate  over  the  inferior  inarticulate  fam- 
ilies (Obolellidse,  Siphonotretidse  and  Lingulidse)  which 

*  "The  first  true  corals  ....  occur  near  the  base  of  the  Silurian  fauna." 
It  was  disputed  whether  Archceocyathus  was  a  sponge  or  coral.  ButHinde 
and  Walcott  agree  in  placing  it  among  the  Zoantharian  families,  allied  to 
the  perforated  corals.  In  the  later  Cambrians  no  Archosocyathus  is  known 
except  Matthew's  doubtful  A.  pavonoides  from  the  Paradoxides  zone  at  St 
John.  Walcott,  p.  588. 

f  In  the  Lower  Cambrian  a  few  scattered  plates  of  a  Cystid,  perhaps  an 
ISocystites,  are  all  we  know  about  the  beginnings  of  the  Echinodermata. 
Walcott,  p.  588. 

|  Lingulella :  of  four  genera  three  occur  in  the  Paradoxides  zone.  A  cro- 
teta  gemma  ranges  from  the  base  of  the  Lower  into  the  Upper  Cambrian. 
Acrothele  subsidua  ranges  through  Lower  and  Middle,  and  A.  matthewi  in 
the  Middle.  Iphidea  is  Lower  Cambrian  in  Labrador  and  Middle  in  Arizona 
and  Sweden.  Kutorgina  labradorica,  stissingensis,  pannula,  occur  in 
Lower  and  Middle,  the  first  with  a  wide  geographical  range  in  the  Lower 
zone.  Linnarssonia  sagitalis  (var.  taconica)  came  late  in  the  Olenellus 
zone  and  lived  on  with  the  Paradoxides.  Obolella  has  6  species  in  the  Lower, 
none  in  the  Middle,  but  some  in  the  Upper  zone.  Orthis  salemensis  and 
highlandensis  (the  broad  and  the  narrow  hinge  types)  of  the  Lower  zone  is, 
not  known  In  the  Middle,  but  recur  in  Silurian  strata.  Orthisina  orientahs 
of  the  Lower  zone  is  very  like  the  O.  pepina  of  the  Upper  ;  and  O.  festinata 
of  the  Lower  very  like  O.  exporecta  and  O.  billingsi  of  the  Middle  zones. 
Camarella  antiquata  and  minor  -of  the  Lower  zone  have  no  known  exist- 
ence or  representatives  in  the  Middle  and  Upper  zones.  Walcott,  p.  588, 58& 


CAMBRIAN   FOSSIL   LIFE.  195 

abounded  in  the  more  ancient  Cambrian  times,  indicating 
a  general  law  of  progressive  evolution  for  the  whole  class.* 

Lamellibranchiate  shells  were  scarce  in  Lower  Cambrian 
time.  The  class  seems  to  have  sent  three  forerunners  to 
announce  its  coming  at  a  far  distant  subsequent  date.f 

Gasteropod  shells  of  6  genera  (13  species  and  5  varieties) 
have  been  collected  from  the  Lower  zone  in  America  alone, 
viz  :  Scenetta,  Stenotheca,  Platyceras,  Pleurotomaria,  and 
Straparollina.  These  belly-creepers  with  their  conical  or 
horn-shaped,  sharp-edged  and  sharp-pointed  shells,  must 
have  scratched  and  furrowed  the  Cambrian  muddy  sand, 
leaving  those  marks  on  its  layers  which  in  too  many  in- 
stances have  been  taken  for  fossil  seaweeds  and  even  land 
plants.:}: 

Of  Pteropods,  winged  shells,  the  Oldest  Cambrian  sea 
was  full.  Four  genera :  Hyolithes,  HyolitTiellus,  Coleo- 
loides,  Satterella,  embraced  at  least  15  species. § 

*  Walcott,  p.  587.  Superior  and  Inferior  are  terms  which  beg  the  ques- 
tion. It  is  more  likely  that  hinge  or  no  hinge  was  a  point  in  dispute  settled 
by  the  habitat  of  each  species  and  the  adaptability  of  the  shell  to  the  food 
which  that  kind  of  habitat  supplied,  or  to  the  comfort  of  housekeeping  there. 

f  Fordilla  troyensis  and  Modiolopsis  prisca  and  an  undescribed  species. 
These  came  and  disappeared.  None  have  been  seen  in  the  Middle  or  Upper 
zones.  Suddenly  a  group  of  species  is  seen  in  the  Welsh  Arenig  rocks 
(Lower  Silurian).  In  Devonian  times  the  class  flourished  in  all  seas. 

JThe  Scenellas  of  the  Lower  zone  are  represented  by  at  least  one  species 
in  the  Middle  zone,  and  by  simple  Patelloid  shells  in  the  LTpper  zone. 
Stenotlieca  rugosa  of  the  Lower  zone  is  closely  allied  to  8.  acadica  of  the 
Middle  zone.  A  small  Platyceras  in  the  Lower  zone  is  represented  by  P. 
romingeri  in  the  Middle ;  and  one  single  species  found  in  the  Upper  zone 
passes  the  genus  on  upward  into  the  Ordovician  (L.  Sil.)  age.  Pleuroto- 
maria  attleboroughensis  of  the  Lower  zone  "does  not  appear  to  have  a  rep- 
resentative before  reaching  the  Lower  Ordovician  fauna."  Straparollina 
remota  of  the  Lower  zone  has  no  known  connection  with  the  Ordovician. 

§  Hyolithes  princeps,  a  large  and  abundant  shell,  had  a  range  from  Ne- 
vada to  Newfoundland,  and  seems  to  have  lived  into  the  Newfoundland 
Paradoxides  (Middle)  zone  ;  and  it  differs  only  in  details  from  the  Bohemia 
H.  maximus  of  that  zone.  H.  americanus  of  the  Lower  zone  is  closely 
allied  to  H.  acadica  and  H.  primordialis  of  the  Middle  zone.  H.  billingsi 
is  found  in  Lower  and  Middle,  in  Labrador,  New  York  and  Nevada.  H. 
similis  is  like  H.  primus  of  the  Bohemian  Middle  zone.  H.  communis, 
impar,  quadricostatus,  terranovicus  have  not  yet  been  found  in  the  Middle 
zone.  Hyolithellus  and  Coleoides  are  not  certainly  known  in  the  Middle 
zone.  "Salterella  oi  the  Lower  Cambrian  is  not  again  met  until  the  Ordo- 
vician fauna  is  reached,  and  there  very  doubtfully."  Walcott,  p.  590. 


196  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

Of  Crustaceans  five  genera  (8  species  have  been  found  in 
the  Lower  Cambrian  zone,  viz.,  Isoxys,  Leperditia,  Aris- 
tozoe,  Nothozoe  and  Protocaris.  It  is  as  wonderful  as  any- 
thing else  in  geology,  finding  thus  a  world  of  schrimps  in 
the  first  hour  of  the  long  day  of  the  planet's  life.* 

Trilobites^  of  16  genera  (53  species),  constitute  nearly 
one- third  of  the  entire  Lower  Cambrian  fauna  ;  trilobites 
with  eyes,  and  trilobites  blind  ;  trilobites  with  facial  sutures, 
and  trilobites  with  unjointed  faces  or  head  shields :  Ag- 
nostus  (3),  Microdiscus  (8),  Olenellus  (7),  Olenoides  (3), 
Zacanthoides  (2),  Bathynotns  (1),  Avalonia  (1),  Cono- 
coryphe  (2),  Ptychoparia  (10),  Agraulos  (3),  Crepicepha- 
lus  (2),  Oryctoceplialus  (1),  Anomocare  (1),  Protypus  (4), 
Solenopleura  (5  species),  f 

*Of  the  true  crustaceans  Leperditia  dermatoides  has  two  representatives  in 
the  Middle  zone.  Isoxys  is  a  new  genus.  Aristozoe  has  not  been  found  in 
the  Middle  zone,  but  in  Europe  it  has  many  Silurian  species.  Of  the  Phyl- 
lopod  crustaceans  Protocaris  marshi  is  the  earliest  known,  the  next  being 
Hymenocaris  vermicauda  of  the  Upper  zone.  Walcott,  p.  590. 

t  Agnostus,  which  has  been  theoretically  considered  the  lowest  and  oldest 
and  ancestral  form  of  all  the  trilobites,  seems  not  to  have  lived  early  in  the 
Obolellus  zone;  undoubted  specimens  having  been  found  only  in  the 
upper  part  of  the  zone  and  with  Middle  Cambrian  forms ;  for  Ford's  Ag- 
nostus nobilis  is  probably  Microdiscus.  In  Sweden  it  seems  also  to  belong 
more  to  the  Middle  zone. 

Microdiscus,  with  its  3  or  4  segments  and  no  eyes,  is  found  at  the  base  of 
the  Lower  zone,  a,nd  with  so  many  species  (8)  must  have  had  a  long  previ- 
ous existence,  coming  to  a  maximum  development  in  the  Lower  and  fading 
away  in  the  Middle  zone  (as  the  Agnostus  increased  in  importanc),  and 
being  represented  in  the  Upper  zone  by  the  solitary  Pernphigaspis  bullata 
of  Hall  (while  Agnostus  lived  on  into  Ordivician,  L.  Silurian,  times). 

Olenellus  is  known  from  all  Lower  Cambrian  areas  except  New  Bruns- 
wick. It  varies  so  that  Walcott  has  grouped  some  of  its  species  in  a  sub- 
genus  (Mesonacis)  and  Matthew  has  proposed  Holmia  to  include  O.  kjer- 
ulfi.  It  differs  from  Paradoxides  in  having  no  true  facial  sutures,  in  the 
lorm  of  the  central  portion  of  the  head,  and  in  the  form  of  its  eyes.  0. 
thompsoni  differs  most  strongly  from  Paradoxides,  which  latter  has  nothing 
at  all  like  the  long-tail  spine  (telson).  But  O.  (Mesonacis)  vermontana 
with  its  typical  Paradoxidean  tail-piece  (pygidium)  links  the  two  groups  of 
species  of  Olenellus  together.  Walcott  invites  attention  to  the  fact  that  there 
is  a  depressed  line  on  the  under  side  of  the  head-shell  of  Olenellus  corres- 
ponding to  real  suture  in  Paradoxides.  Also,  that  Olenellus  resembles  our 
King  Crab  (Limulus)  in  haAang  well-developed  eyes  without  having  facial 
sutures,  not  to  speak  of  its  tail-spike.  He  thinks  the  Newfoundland  O. 
broggeri  as  highly  or  more  highly  organized  than  any  Paradoxides.  Amer- 
ican paleontologists,  he  adds,  have  considered  Olenellus  the  descendant  of 


CAMBRIAN   FOSSIL   LIFE.  197 

The  study  of  the  Olenellus  fauna  proves  that  an  immense 
time  had  already  elapsed  since  the  beginning  of  life  on  the 
planet,  Daring  Cambrian  times  the  evolution  of  life  pro- 
duced almost  no  new  classes  of  living  creatures,  but  only 
new  generic  and  specific  variations  of  those  which  were  al- 
ready in  existence.  The  most  notable  apparent  exception 
to  this  statement  is  found  in  the  subsequent  appearance  of 
the  class  of  Cephalopod  shells  (Orthoceras,  Lituites,  etc.), 
none  of  which  have  as  yet  been  found  in  rocks  below  the 
Silurian.*  It  is  hardly  necessary  to  add  that  nothing  is 
known  of  fossil  lishes  in  the  Cambrian,  much  less  of  any 

Paradoxides,  but  it  has  turned  out  that  Olenellus  lived  first.  The  student 
of  Evolution  may  profitably  ponder  on  the  paragraphs  of  his  592d  page. 

Olenoidcs  marcoui  is  the  only  species  found  in  the  lower  portion  of  the 
Olenellus  zone  (the  other  two  border  on  the  Paradoxides  zone)  and  seems 
closely  related  to  O.  nevadensis  of  the  Paradoxides  zone.  Zacanlhoides 
eatoni  and  levis  serve  to  unite  the  two  zones.  Bathynotus,  Avalonict, 
Oryctocephalus  and  Protypus  are  genera  confined  to  the  Olenellus  zone. 

The  blind  Conocoryphe  trilineata,  and  reticulata  are  two  of  the  best- 
marked  types  01  the  Lower  zone,  but  are  closely  related  to  the  blind  elegans 
and  coronata  of  the  Middle  zone. 

Ptycoparia  has  nine  species,  all  more  or  less  closely  related  to  Middle  and 
Upper  Cambrian  forms.  The  Lower  Cambrian  Agraulos  slrenuus  is  rep- 
resented by  the  Upper  Cambrian  A.  socialis.  Ellipsocephalus  has  a  species 
in  the  Lower  and  in  the  Middle  zones.  Crepicephalus  augusta  and  liliana 
are  also  Upper  Cambrian,  but  have  not  been  found  in  the  Middle  zone. 
Solenopleura  is  also  well  developed  in  the  Middle  zone. 

Walcott  concludes  (page  593)  that  we  have  a  poor  knowledge,  as  yet,  of 
the  Middle  (Paradoxides)  fauna  and  may  expect  great  discoveries  to  bo 
made  somewhere  "on  the  western  slope  of  the  Apalachian  shore,  and  on  the 
west  coast  of  what  then  existed  as  the  North  American  continent."  The 
Paradoxides  fauna  is  merely  a  contribution.  Surely  the  Lower  Cambrian 
creatures  continued  in  existence  longer  than  the  rocks  as  yet  have  shown. 
For  instance,  what  became  of  the  Archseocyathine  corals  of  the  Lower 
Cambrian?  Obolella  had  a  fine  development  in  Upper  Cambrian  time, 
why  is  it  almost  completely  absent  from  the  Middle  Cambrian  rocks? 
What  happened  to  the  Brachiopod  shells  as  a  class  to  render  the  number  of 
both  their  species  and  individuals  smaller  in  Middle  Cambrian  time  than 
before?  We  have  Lamelli-branch  shells  from  the  Lower;  none  Irom  the 
Middle.  So  also  of  the  Gasteropods  Pleurotomaria  and  Straparollina,  and  the 
Phyllopod  crustacean  Protocaris  marshi,  "The  cause  of  the  abrupt  change 
from  the  Olenellus  to  the  Paradoxides  faunas  is  not  yet  fully  recognized. 
While  a  considerable  number  of  the  genera  pass  up,  very  few  of  the  species 
are  known  to  do  so,  and  in  none  of  the  sections  has  there  been  found  a  com- 
mingling of  the  characteristic  species  of  the  Lower  and  Middle  faunas." 
(Walcott,  page  594.) 

*  Walcott,  page  595. 


198  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

fossil  vertebrates  of  a  higher  order,  reptilian  or  mammalian. 
But  whereas  only  three  or  four  years  ago  it  was  disputed 
whether  our  Perry  county  Upper  Silurian*  fish  spines  and 
plates  (the  oldest  known  to  science)  were  not  the  spines  and 
plates  of  crustaceans,  and  whereas  now  true  fish  remains 
have  been  found  in  the  Lower  Silurian  (Ordovician)  Tren- 
ton limestone  in  the  Rocky  mountains,!  it  is  easy  to  fancy 
that  cephalopod  shells  'and  ganoid  fish  may  have  lived 
even  in  Cambrian  times.  As  yet  no  air-breathing  land  ani- 
mal remains  have  been  discovered  in  any  rocks  older  than 
the  Carboniferous ;  but,  considering  the  extreme  difficul- 
ties attending  their  preservation,  as  compared  with  the  easy 
and  safe  burial  of  water  animals,  it  is  not  at  all  a  wild  con- 
jecture that  some  sharp  eye  will  light  upon  the  traces  of 
their  existence  in  earlier  ages4  Only  a  few  years  ago  the 
Cambrian  rocks  were  supposed  to  be  non-fossiliferous.  I 
have  inserted  this  chapter  on  Cambrian  fossil  life  to  guide 
and  stimulate  students  of  geology  in  Pennsylvania,  especi- 
cially  the  more  youthful,  curious  and  keen-sighted,  to  a 
closer  examination  of  our  so-called  "Azoic"  or  "No-life" 
formations. 

*See  Claypole's  discoveries  in  the  Clinton  formation  No.  V  a.  in  Report  F2. 

f  See  C.  D.  Walcott's  descriptions  read  at  Washington,  August,  1891. 

JIf  the  discovery  of  a  Silurian  cockroach  wing  in  Calvados,  France,  be 
genuine,  there  was  a  Silurian  world  of  land  insects,  and  of  course  of  land 
animals  to  devour  them.  If  Lesquereux  was  not  mistaken  about  his  fossil 
Silurian  land  plants,  there  must  have  been  land  animals  living  upon  their 
fruit  or  foliage.  In  all  ages  foods  have  been  followed  (or  accompanied)  by 
feeders.  On  the  other  hand,  feeders  presuppose  foods.  What  did  the  Lower 
Cambrian  worms,  polyps,  shells  and  crustaceans  live  upon  ?  Certainly  not 
upon  mineral  matter.  Worms  pass  vast  quantities  of  mineral  matter 
through  their  intestinal  canal  and  leave  it  packed  behind  them  in  their  bur- 
rows, and  this  packing  constitutes  mostof  the  "fossil  cast. "  But  they  do  this 
in  order  to  suck  from  the  surface  of  the  grains  of  sand  and  mud  organic 
matter  which  must  have  belonged  to  other  creatures  either  alive  or  dead. 
If  alive,  then  microscopic  animalcules.  If  dead,  then  the  decomposed 
tissues  of  other  worms,  shell-fish,  etc.,  absorbed  by  the  sand  and  mud. 
But  the  first  worms  must  have  found  living  food.  If  the  worms  came  first 
and  the  polyps  and  mollusks  afterwards,  then  the  beginnings  of  life  must 
be  conceived  of  as  microscopic,  cellular  and  vegetable  ;  in  other  words,  an 
Algoid  or  seaweed  world,  feeding  on  the  chemical  elements  of  the  rocks 
held  in  solution  by  the  ocean  water ;  therefore  casts  of  sea  weeds  in  the  oldest 
rocks  must  be  realities  and  not  mechanical  imitations. 


SOUTH  VALLEY  HILL  SLATE  BELT.          199 


CHAPTER  XIX. 
South  Valley  Hill  slate  belt. 

Before  leaving  the  dark  geology  of  southern  Pennsyl- 
vania to  enter  upon  the  brilliantly  illuminated  geology  of 
the  middle  region,  something  more  must  be  said  of  those 
enigmatical  belts  of  hydro-mica  slates  which  Prof.  Rogers 
placed  as  his  Upper  and  Lower  Primal  slates,  above  and 
below  the  Cinques  quartzite  (N.  Valley  Hill  sandstone) — 
which  Dr.  Frazer  places  wholly  above  it — and  which  Mr. 
Hall  placed  still  higher,  above  the  great  limestones,  as 
Hudson  river  slates  in  an  altered  condition. 

In  York  county  the  last  theory  receives  no  support.  A 
belt  of  hydro-mica  slate  surrounds  the  Hellam  quartzite 
area  between  Chiques  rock  and  York,  and  is  surrounded  by 
the  limestone  of  York  valley  and  the  Codorus.  The  hydro- 
mica  beds  are  evidently  above  the  quartzite  and  beneath  the 
limestone  ;  and  they  run  on  between  two  belts  of  limestone 
to  the  Pigeon  Hills,  and  along  the  south  side  of  the  hills 
into  Adams  county,  where  they  enclose  the  southwest  end 
of  the  limestone  area,  and,  uniting  with  the  broad  belt  of 
hydro-mica  country  south  of  the  limestone,  pass  into  Mary- 
land, where  Mr.  Keyes  finds  them  overlying  the  Sugarloaf 
and  Cotoctin  quartzite. 

South  of  the  York  limestone  belt  at  Wrightsville,  on  the 
river  opposite.  Columbia,  a  hydro-mica  belt  a  third  of  a  mile 
wide  between  the  limestone  and  a  long  outcrop  of  quartzite 
runs  west  to  the  South  Branch  Codorus,  where  its  width  is 
five  miles,  widens  to  six  miles  at  Xenia,  and  contracts  to 
three  miles  at  the  Adams  county  line.  Many  isolated  out- 
crops of  quartzite  are  located  on  the  map  inside  this  belt, 
and  they  should  represent  sharp  anticlinal  rolls  of  quartzite 
exposed  by  erosion. 

The  phyllite  ("Chlorite  schist")  belt,  already  described 


200  x  GEOLOGICAL   SURVEY    OF   PENNSYLVANIA. 

in  a  previous  chapter,  borders  this  great  hydro-mica  schist 
belt  on  the  south,  and  two  long  prongs  of  phyllite  country 
penetrate  the  hydro-mica  belt,  one  pointing  west  towards 
the  S.  Br.  Codorus,  the  other  pointing  east  to  the  river  a 
mile  below  Wrightsville,  both  on  one  line,  and  the  two  rep- 
resenting (theoretically)  an  eleven-mile  long  anticlinal  ex- 
posure of  the  phyllites  from  under  the  hydro-micas. 

Around  the  east  point  of  the  east  phyllite  prong  at  the 
river  below  Wrightsville,  and  along  its  southern  side  from 
the  river  west  for  six  miles,  there  runs  another  belt  of 
hydro  mica  slates,  bordered  on  the  south  by  the  limestones. 
As  an  outcrop  of  quartzite  borders  the  north  side  of  the 
phyllite  prong  and  laps  around  its  pointed  end  onto  its 
southern  side,  it  seems  evident  that  the  hydro-mica  over-lie 
the  quartzite  and  under-lie  the  limestone. 

But  why  is  there  not  such  an  outcrop  of  the  quartzite 
between  the  phyllites  and  hydro-micas  along  the  whole 
contact  line  across  the  county?  There  is  but  one  answer  : 
The  quartzite  is  an  insignificant  formation,  an  irregular  de- 
posit, thin  here,  thick  there,  absent  altogether  elsewhere, 
and  in  fact  generally  towards  the  south.  This  seems  to  be 
the  case  in  Chester  county,  and  especially  in  southern  Lan- 
caster. But  if  so,  then  the  contact  plane  of  hydro-mica  on 
phyllite  must  be  insignificant,  unreliable  and  deceptive ; 
and  the  contact  line  between  the  two  great  belts  in  York 
county  can  hardly  be  relied  upon  as  accurate.  In  fact  the 
distinction  between  the  Chlorite  schists  and  Hydro-mica 
slates  is  not  recognized  by  the  Maryland  geologists ;  and 
Dr.  Frazer  says  that  chlorite  slates  occur  in  the  hydro-mica 
belt.  He  establishes  the  distinction  on  a  general  larger 
proportion  of  magnesia  in  the  lower  and  less  in  the  upper ; 
and  on  the  local  separation  of  the  two  by  the  quartzite 
beds.  That  is  precisely  what  Prof.  Rogers  did  in  con- 
structing his  series  of  Primal  lower  slate,  Primal  (middle) 
sandstone,  and  Primal  upper  slate.  But  then,  the  chloritic 
phyllites  of  York  become  the  Primal  lower  slate  of  the 
South  Valley  Hill  in  Chester.  Whereas  I  understand  Dr. 
Frazer' s  Chester  county  report  .to  make  the  South  Valley 
Hill  a  belt  of  the  hydro-mica  slates. 


SOUTH  VALLEY  HILL  SLATE  BELT.         201 

I  see  but  one  solution  of  the  problem,  which  if  correct 
will  conciliate  the  apparently  contradictory  identifications 
of  these  two  able  geologists,  viz.,  that  both  the  lower  more 
magnesian  and  upper  less  mftgnesian  series  are  present  to- 
gether in  the  South  Valley  Hill.* 

The  South  Valley  Hill  slate  belt  is  two  miles  wide  at  the 
east  end  of  Chester  county,  and  the  slates  stand  vertical. 
That  means  10,000  feet  of  slates  !  To  diminish  this  enor- 
mous thickness  to  agree  with  his  observations  on  the  oppo- 
site side  of  the  valley  (in  the  North  Valley  Hill)  Mr.  Rogers 
supposed  many  tightly-compressed  rolls.  Certainly  two 
such  rolls  show  in  the  double-spurred  east  end  of  the  hill 
at  the  Schuylkill.f  But  two  rolls,  whether  anticlinal  or 
synclinal  (and  there  is  not  room  for  more)  will  not  reduce 
the  thickness  to  one-fourth.  There  would  still  be  more 
than  2,000  feet  of  slates. $ 

Opposite  West  Chester  the  belt  is  three  miles  wide  ;  op- 
posite Coatesville,  five  miles  wide ;  before  reaching  the 
Lancaster  line,  still  wider  ;  and  so  continues,  covering  much 
of  the  southern  townships  of  Lancaster ;  a  region  where 
Dr.  Prazer  does  not  feel  justified  in  mapping  a  contact  line 
between  his  chloritic  series  and  hydro-mica  series.  In 

*In  this  case  however  we  must  neglect  Prof.  Rogers'  obscure  outcrop  of 
the  Primal  sandstone  at  the  north  foot  of  the  hill,  along  the  border  of  the 
limestone. 

fThe  two  "synclinals"  on  which  C.  E.  Hall  relies  for  placing  the  slates 
over  the  limestone  ;  the  two  "anticlinals"  on  which  Dr.  Frazer  relies  (in  this 
vicinity)  for  placing  the  slates  beneath  the  limestone. 

J  Rogers  conjectures  that  his  Primal  Lower  slates  between  the  Brandy- 
wine  and  Adams  county  may  be  2,000  feet  thick  ;  in  Virginia  1,200,  with  150 
additional  as  a  conglomerate  base  which  does  not  appear  in  Pennsylvania. 

His  Primal  Sandstone,  around  the  outlying  limestone  patches  of  southern 
Chester,  in  the  Street  road  and  in  Dochranaman  hill,  thin;  then  at  Peach  Bot- 
tom on  the  Susquehanna,  90'  ;  in  Chiques  rock,  U.  SS.  27',  slate  parting  300 
L.  SS.  with  bands  of  slate,  300',  total  627  ;  at  Parkesburg,  Chester  Co.,  U.  SS. 
20  ,  slate  300',  L.  SS.  50,  total  370 ;  at  Coatesville,  Chester  Co.,  U.  SS.  40',  slate 
70',  L.  SS.  15',  total  125  ;  at  Edgehill,  300' ;  at  Willow  Grove,  100'  ;  on  Schuyl- 
kill  and  Wissahickon,  40'  ;  Durham  on  the  Delaware,  100  ;  Chesnut  Hill 
north  of  Easton,  100'  ;  below  Reading  thicker,  but  too  much  crumpled  to 
measure. 

His  Primal  Upper  slates,  wanting  east  of  Willow  Grove;  Barren  Hill, 
thin ;  Diamond  rock  and  Paoli  section,  300 '  ? ;  Coatesville,  700'  ;  Parkes- 
burg, partly  visible,  300'+;  Columbia  and  Chiques  about  1,000'.  (Geol. 
Pa.,  1858,  page  122.) 


202  GEOLOGICAL   SURVEY   OF   PENNSFLVANIA. 

fact  hydro-mica  slates  with  chloritic  interpolations  and 
chloritic  slates  with  hydro-mica  interpolations  can  be  called 
"phyllites"  with  equal  propriety  (are  so  called  in  the 
Maryland  survey)  and  alike  belong  really  to  one  system  of 
sediments,  more  or  less  magnesian. 

Now,  it  would  be  wonderful  indeed,  if  there  were  not 
sand  beds  in  two  or  three  thousand  feet  of  mud  deposits. 
When  the  magnesian  muds  were  altered  into  chlorites  and 
the  potash-soda  muds  into  hydro-micas,  then  necessarily 
the  sand  beds  became  quartzites.  So  we  ought  to  expect 
sporadic  quartzite  beds  in  the  slate  belts.  The  occasional 
quartzite  spots  on  the  York  county  map  in  the  phyllite 
belt,  and  much  more  numerously  in  the  hydro-mica  belt, 
may  therefore  have  nothing  to  do  with  the  Hellam-Chiques 
quartzite,  which,  itself,  as  we  have  seen,  actually  plays  the 
same  role  of  irregular  distribution  over  its  original  floor  as 
all  lenticular  sand  deposits  do  of  every  age.* 

The  South  Valley  Hill  hydro-mica  schist  belt  from  the 
Delaware- Chester  county  line  west  to  the  Brandywine  has 
a  south  border  fairly  denned  by  a  straight  range  of  ser- 
pentine outcrops  and  limestone  quarries.  "  The  line  crosses 
the  railroad  south  of  Patton  station,  cutting  across  the  north 
end  of  West  Chester,  to  the  Brandywine  at  the  mouth  of 
Valley  creek,  and  the  west  branch  at  Embreeville  ;  passing 
along  the  north  side  of  the  Doe  run  limestone  and  the  little 
gneiss  area  of  Buck  run.  But 'hence  westward  through 
Londonderry,  Upper  Oxford  and  Lower  Oxford  "there  is 
an  indefinable  transition  from  the  belt  of  mica  slate  to  the 
felspathic  micaceous  gneiss  country  which  borders  it  on  the 
south  f 

*The  Oriskany  sandstone,  Formation  No.  VII,  is  a  notable  example  of 
this  general  law,  as  we  shall  see  in  a  future  chapter.  If  it  had  been  pre- 
served from  erosion  in  a  metamorphic  region  it  would  be  almost  a  facsimile 
of  the  Chiques  quartzite.  The  Chiques  quartzite  ought  not  to  be  regarded 
as  a  unique,  nor  reasoned  on  as  a  universal  formation  of  recognizable  class- 
ical age  and  place  in  the  great  series.  That  would  be  to  repeat  the  old  error 
of  the  "Potsdam  sandstone."  It  is  but  one  of  many,  and  our  sketch  of  the 
South  mountains  in  a  previous  chapter  shows  its  insignificance  in  compari- 
son with  the  huge  quartzite  formations  underlying  the  hydro-mica  and 
chlorite  slates  of  that  range  of  mountains. 

fCriticising  the  map  of  Chester  county  which  he  was  unable  to  revise  be- 
fore its  publication,  Dr.  Frazer  writes:  "The  chloritic  and  hydro-mica 


SOUTH  VALLEY  HILL  SLATE  BELT.         203 

The  general  tint  of  the  slates  is  greenish,  and  the  beds 
are  frequently  separated  by  lenticular  beds  of  light-colored 
or  pure  white  quartz.  The  slates  along  the  southern  edge 
of  the  belt  are  somewhat  garnetiferous  ;  and  at  two  places, 
at  Williston  and  East  Goshen,  turn  into  a  true  garnetiferous 
schist.  All  the  roads  indicate  its  presence,  but  the  best 
exposures  are  along  the  creeks  and  railway  cuts  descending 
to  the  valley.* 

The  South  Valley  Hill  hydro-mica  slates  are  therefore 
not  the  York  county  hydro-mica  slates  of  Dr.  Frazer  above 
the  Chiques  quartzite,  but  the  chloritic  phyllites  lying  di- 
rectly upon  the  Tocquan  (Philadelphia)  gneisses  and  mica 
schists,  and  may  in  fact  be  the  upward,  continuation  of  C. 
E.  Hall's  garnetiferous  (Chestnut  Hill)  upper  sub-division 
of  the  Philadelphia  series,  f 

The  South  Valley  Hill  belt  holds  so  straight  a  course  for 
fifty  miles  from  the  Schuylkill  into  Lancaster  county  that 
there  can  be  no  doubt  of  its  extension  to  the  Susquehanna 

schist  areas  in  York  and  Lancaster  were  easily  distinguishable,  both  from 
the  less  thoroughly  metamorphic  appearance  of  the  latter,  and  from  the  fact 
that  the  quartzite  (Potsdam)  generally  came  in  between  them.  This  was 
generally  true  of  the  chlorite  and  underlying  gneisses,  though  an  isolated 
patch  of  the  former  in  the  latter  on  the  Lancaster  county  map  (with  no  defi- 
nite upper  boundary)  is  frankly  acknowledged  in  the  text  to  be  an  attempt 
at  a  lithological  distinction  run  into  a  cul  de  sac,  though  abundantly  justi- 
fied and  confirmed  by  a  close  study  of  the  rocks  in  its  strike  in  Chester 
county.  When  Chester  county  was  reached  all  sharply-defined  boundaries 
ceased  to  be  possible.  The  quartzite  faMed  altogether  on  the  southern  side 
of  the  valley,  the  mica  schists  became  more  gneissoid,  the  gneisses  showed 
chlorites,  and  the  chlorites  modified  their  distinctive  character.  Add  to  this 
that  a  thin  unknown  series,  representing  the  rotten  representatives  of  all 
these,  has  since  appeared  to  increase  the  confusion.  Nevertheless  an  at- 
tempt was  made  to  define  on  the  Chester  county  map  the  chloritic  masses 
wherever  the  eye  detected  them,  leaving  an  explanation  of  them  for  a  future 
task.  The  result  however  was  to  completely  demonstrate  the  futility  of 
separating  the  chlorites  from  the  mica  schists  in  this  area  (Chester  county.) 
The  area  became  dotted  over  with  small  and  large  masses  of  chlorites  which 
preserved  no  regularity  in  dip,  strike,  zone,"  etc.  (Report  C4,  page  35. 
Italicised  by  J.  P.  L.) 

*  Notes  by  C.  E.  Hall,  published  in  Report  on  Chester  Co.,  C4,  page  60. 

|  Then  the  serpentine  at  the  top  of  this  sub-division  (at  Lafayette  station 
on  the  Schuylkill)  would  coincide  with  the  serpentine  at  the  bottom  (or 
south  edge)  of  the  North  Valley  Hill  slates  (south  of  Greentree,  and  west  to 
West  Chester)  and  also  with  the  serpentine  of  Lancaster  along  the  south 
edge  of  the  Peach  Bottom  phyllite  belt. 


204  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

river  twenty  miles  farther  on  ;  and  the  county  maps,  in 
spite  of  their  inconsistent  coloration,*  when  laid  together 
show  that  the  straight  forward  continuation  of  the  belt 
brings  it  to  the  Susquehanna  where  the  Peach  Bottom  phyl- 
lites  exhibit  themselves  for  five  miles  in  cross- section, 
mostly  vertical  or  on  very  steep  dips,  bnt  complicated. 

Prof.  Rogers  was  therefore  correct  in  calling  the  S. 
Valley  Hill  schists  Primal  Lower  slates  ;  and  no  doubt  if 
exposures  allowed  we  could  see  them  graduating  down  ward 
into  the  upper  schists  and  gneisses  of  western  Chester  and 
southern  Lancaster  just  as  they  seem  to  do  across  York 
county,  f 

In  spite  of  their  general  vertical  or  steep  dips  they  are 
undoubtedly  closely  and  tightly  crumpled  into  innumer- 
able more  or  less  parallel  small  anticlinals  and  synclinals, 
upon  a  general  floor  of  Philadelphia  (Tocquan)  newer 
gneiss  ;  and  that  this  floor  participates  in  the  crumpling  is 
proven  by  its  frequent  and  sometimes  abundant  appearance 
at  the  present  surface  along  lines  and  over  larger  or  smaller 
areas  of  erosion  from  which  the  chlorite  hydro-mica  slates 
have  been  removed. 

Prof.  Rogers  was  also  correct  in  extending  the  South 
Valley  Hill  belt  of  slates  to  the  Susquehanna,  although  in 
his  final  report  he  confined  their  identification  chiefly  to 
the  phyllite  and  hydro-mica  slate  region  of  middle  York 
county  north  of  the  Tocquan  gneiss.  That  he  identified 
them  also  with  Peach  Bottom  belt  slates  is  evident  from  his 
seeking  there  and,  as  he  supposed,  finding  an  outcrop  of 
Chiques  quartzite,  90  feet  thick,  which  he  calls  "its  most 
southern  appearance  in  the  state. "^ 

*For  which  I  hold  myself  solely  responsible. 

f  This  view  certainly  simplifies  the  geology  of  our  southeastern  counties 
but  it  is  not  wholly  satisfactory,  for  it  fails  to  explain  the  hornblendic  gneiss 
areas  of  Delaware  county,  leaving  it  an  open  question  whether  they  are  vol- 
canic outflows,  or  anticlinal  (or  fault)  uplifts  of  older  sedimentary  fully 
crystallized  rocks. 

JGeol.  Pa.,  1858,  I,  p.  122,  and  special  detailed  description,  page  189,  which 
I  have  inserted  verbatim  in  chapter  16,  page  183,  above.  It  is  a  fine  example 
of  the  lucid  and  forcible  style  of  the  great  geologist  of  Pennsylvania,  the 
closeness  of  his  field  observation,  and  the  wealth  of  material  facts  to  be 
found  in  his  immortal  book.  Would  that  he  had  been  himself  immortal, 
and  on  earth  to  conduct  the  second  geological  survey  of  the  state,  and  to 
write  this  summary  of  it  instead  of  myself. 


IRON   MINES   IN   THE   PRIMAL   UPPER   SLATE.  205 


CHAPTER  XX. 
Iron  mines  in  the  Primal  upper  slate. 

Many  of  the  first-class  limonite  (brown  hematite)  mines 
of  Pennsylvania  are  in  Rogers'  Primal  Upper  slates,  over 
the  Chiques  quartzite  and  under  the  Great  Valley  limestone. 
Such  are  the  Chestnut  Hill  mine  back  of  Columbia  in  Lan- 
caster, the  Warwick  (Jones)  mine  in  the  south  corner  of 
Berks,  the  Trexler  mine  in  Lehigh,  the  Old  bank  in  Cum- 
berland, and  the  Mont  Alto  banks  in  Franklin,  and  a 
large  number  of  other  more  or  less  important  open  mines 
elsewhere ;  some  dating  far  back  in  the  last  century,  and 
others  but  a  few  years  ;  some  abandoned  if  not  exhausted, 
others  actively  exploited  at  present  whenever  the  iron  in- 
dustry is  prosperous.* 

It  is  not  always  easy  to  account  for  the  vast  quantities  of 
iron  ore  collected  by  nature  at  these  mines.  In  some  in- 
stances the  whole  mass  of  slate  seems  to  have  been  changed 
into  ore  by  a  sort  of  chemical  cookery ;  the  original  slaty 
stratification  remaining  visible,  but  in  so  wavy  a  state  as  to 
suggest  both  a  swelling  and  a  settling  of  the  mass  against 
the  walls  of  a  gigantic  chaldron. f 

In  other  cases  the  ore  seems  to  be  a  sediment,  with  clay, 
brought  into  a  depression  by  inflowing  waters  which  had 
passed  through  the  slate  rocks  and  obtained  by  a  leaching 
process  the  iron  which  they  contained  ;  the  clay  being  a  de- 
composition of  the  felspathic  body  of  the  rock.  The  pot- 
like  mines  of  Cumberland  and  Franklin  ranging  along  the 

*  Other  similar  and  even  more  important  mines  not  mentioned  in  this 
chapter  will  be  described  in  a  future  chapter,  because  they  belong  geograph- 
ically to  the  belts  of  limestone  outcrops,  although  geologically  they  originate 
in  the  same  way  from  the  decomposition  of  slates  of  much  the  same  kind, 
but  placed  higher  in  the  series  of  formations. 

t  See  the  pen  and  ink  sketch  of  the  Chestnut  Hill  mine  face  as  it  looked 
forty  years  ago  in  Rogers'  Geol.  Pa.  1858,  I,  page  183,  fig.  24«. 


206  GEOLOGICAL   SURVEY   OP   PENNSYLVANIA. 

foot  of  the  South  Mountain,  ending  with  the  Mont  Alto 
banks,  are  certainly  of  this  character.* 

The  hydromica  slates  of  York  and  Lancaster  are  not 
uniform  in  aspect.  The  beds  immediately  beneath  the 
limestone  are  massive  enough  to  make  hills,  like  those 
which  line  the  Susquehanna  from  Wrightsville  to  Cabin 
Branch  run.  Others  of  the  series  are  disintegrated  to  a 
dust  of  little  glinting  particles  of  mica.  The  more  solid 
beds  contain  innumerable  beautifully  perfect  cubical  crystals 
of  pyrites  (sulphide  of  iron,  and  occasionally  copper)  or 
the  hollow  casts  from  which  such  crystals  have  been  dis- 
solved out.  Here  we  have  one  most  evident  and  copious 
source  of  brown  hematite  (limonite)  iron  ore.f 

There  are  Cambrian  argillites  in  Vermont  which  are  simi- 
larly studded  with  perfect  cubes  of  pyrites.  I  have  seen 
50  on  the  side  of  a  slab  a  foot  square,  most  of  them  casts, 
but  some  of  the  crystals  projecting  from  the  face  of  one 
slab  and  leaving  a  cast  in  the  face  of  the  slab  from  which  it 
was  split  off.  Their  number  was  incalculably  great.  Sup- 
posing the  whole  formation  filled  with  them  on  an  even 
distribution  there  would  be  67,500  in  a  cubic  yard,  and  a 
hundred  thousand  million  of  them  in  an  outcrop  a  mile 
long  by  90'  wide  and  90'  deep.  As  most  of  them  were  only 
a  tenth  of  an  inch  on  a  side,  27,000  would  go  to  make  a 
cubic  yard  of  solid  pyrites,  weighing  say  2£  tons  of  iron 
and  2|  of  sulphur,  and  such  a  prism  of  country  would  hold 
about  a  million  and  a  half  tons  of  iron.  Usually,  however. 

*See  my  description  of  them  in  Proc.  Amer.  Pbilos.  Soc.  Jan.  3,  1873.  But 
these  deposits,  although  on  the  outcrop  of  the  slate,  and  deriving  their  birth 
from  it,  are  of  a  very  late  age.  The  same  may  be  said  of  the  great  Hunting- 
don county  banks,  formed  in  the  same  way  and  time  from  similar  slates, 
higher  up  in  the  series,  interpolated  among  the  great  limestones.  See  my 
Report  to  Lyon,  Shorb  <fe  Co.  ^1874),  incorporated  into  the  Reports  of  Pro- 
gress in  Huntingdon  and  Centre  counties,  T3,  T4. 

t  Frazer,  Amer.  Philos.  Soc.  Dec.  4,  1885,  page  40L  When  a  boy,  at  Lafay- 
ette's visit  to  Lancaster,  I  had  given  me  a  lot  of  these  crystals  which  had 
been  picked  from  the  bed  of  a  stream.  They  were  about  the  size  of  dice, 
but  varied  on  an  edge  up  to  an  inch  and  down  to  the  sixteenth  of  an  inch ; 
blackish-brown  on  the  surface;  when  broken,  a  glittering  gold  within; 
most  of  them  absolutely  perfect  cubes,  but  some  with  imperfect  corners, 
not  from  recent  fracture,  for  the  defective  corners  had  the  same  brown  skin 
as  the  sides. 


IKON   MINES   IN   THE   PRIMAL   UPPER   SLATE.  207 

the  slates  contain  the  iron  in  the  form  of  ferrous  oxide, 
uncrystallized,  and  of  percentages  varying  from  7  down  to 
less  than  1.  Even  so  the  amount  of  iron  held  in  the  rock 
is  quite  sufficient  to  account  for  great  deposits  of  limonite 
produced  by  erosion  and  oxidation  in  clays.* 

The  Chestnut  Hill  ore  l>ank  is  3£  miles  northeast  of  Co- 
lumbia in  Lancaster  county,  in  a  shallow  synclinal  (?)  vale 
on  the  south  flank  of  Chiques  ridge. f  The  ore  is  at  the 
bottom  measures  of  the  slate,  next  over  the  quartzite  which 

*  Dr.  Frazer  discusses  the  origin  of  the  limonite  deposits  in  Report  C, 
1874,  page  137,  and  thinks  it  most  probable  that  it  is  to  be  lound  in  "the 
pyrite  crystals_of  the  brown  slates.  Even  the  slates  which  are  not  so  situated 
as  to  permit  the  percolation  of  water  through  them  exhibit  a  porous 
structure,  the  pores  being  filled  with  brown  ochreous  limonite ;  and  this 
occurs  to  an  unknown  depth,  and  the  slates  seem  to  merge  by  imperceptible 
degrees,  in  a  direction  normal  to  the  plane  bedding,  first  into  completely 
metasomatized  pseudomorphs  of  limonite  after  pyrite  (but  still  retaining 
the  form  of  the  latter);  then  the  same  with  a  kernal  of  pyrite;  then  the 
pyrite  itself,  first  with  a  shell  and  then  with  a  mere  stain  of  ferric  hydrate ; 
and  finally  the  same  slates  are  revealed  porphyritic  from  the  pyrite,  and  not 
at  all  decomposed."  This  suggests  that  the  limonite  was  manufactured  by 
percolating  waters  in  the  body  of  the  slate  mass  and  merely  set  free  by 
erosion  and  gathered  together  into  low  grounds  or  cavities  of  the  surface, 
or  caverns  in  the  neighboring  limestone,  by  running  waters  carrying  the 
mud  of  the  triturated  slates  together  with  the  limonite  of  the  cavities  as  fast 
as  exposed,  and  both  dumped  together  (slowly)  into  the  reservoir  to  settle. 

On  page  139  Dr.  Frazer  makes  his  own  calculation  of  quantity.  A  speci- 
men of  slate  from  under  the  York  limestone  taken  on  the  railroad  five  miles 
southeast  of  York,  3|"x2£",  showed  to  the  naked  eye  350  pits  left  by  decayed 
crystals  of  pyrites,  varying  from  ^  to  ^\  of  an  inch,  or  40  to  the  square  inch. 
Nine  layers  of  such  pits  were  visible  in  the  thickness  of  \  inch.  This  would 
amount  to  12.27  cubic  inches  of  pyrites  in  a  column  one  square  inch  five  feet 
long,  or  32  pounds  in  five  cubic  feet  of  slate.  Every  running  mile  of  outcrop 
five  feet  thick  and  1,000  feet  high  (eroded  from  the  present  surface)  must 
have  yielded  75,000  tons  of  pyrites,  or  48,700  tons  of  iron,  or  80,000  tons  of 
limonite.  He  carries  the  calculation  further  on  page  140,  but  the  above  is 
enough  to  justify  him  in  saying  that  allowing  for  all  contingencies  we  have 
more  than  enough  to  account  for  the  largest  ore  banks. 

f  Dr.  Frazer  does  not  accept  the  simple  synclinal  structure.  Ore  beds  at 
mouth  of  a  drift  250  long  sink  N.  W.  beneath  the  floor  of  the  drift.  In  the 
middle  parts  of  the  mine  the  ore's  lie  flat.  One  or  more  anticlinal  waves  are 
therefore  probable.  On  page  213  he  makes  a  curious,  novel,  but  by  no  means 
useless,  suggestion  that  possibly  the  weight  of  the  high  walls  of  the  open 
mine  has  helped  to  convert  a  shallow  synclinal  into  a  very  low  anticlinal. 
His  numerous  close  observations  to  settle  the  question  of  anticlinal  wave 
structure  of  the  mass  in  this  and  the  neighboring  mine  occupy  several  in- 
structive pages  of  his  book. 


208  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

has  been  exposed  in  the  mine  floor.  The  dips  are  gentle; 
bottom  flat;  an  open  quarry,  100  feet  deep,  ore  from  top  to 
bottom  of  the  slope  walls;  area  in  1856,  about  11  acres,  in 
1877,  1400'  wide  by  3350'  long.  The  old  Grubb  mine  half  a 
mile  east  is  in  the  same  slate  and  merely  a  continuation  of 
the  formation  towards  Lancaster.* 

The  decomposition  of  the  slate  mass  into  limonite  is  evi- 
dent to  the  eye.  The  upper  half  or  more  of  the  walls  are 
of  a  bluish,  yellowish  and  white  greasy  clay,  laminated  as 
it  was  before  the  change.  Underneath  is  a  mass  of  solid 
ore,  10  to  30  feet  deep,  lying  on  the  quartzite  floor;  brown, 
cellular  fibrous  hematite  (limonite)  precipitated  from  above 
as  the  heavier  element  of  the  wet  clay  which  filled  the  hollow. 
The  present  drainage  passed  beneath  the  slate  over  the  face 
of  the  quartzite  ;  and  this  has  always  been  the  agent  of  de- 
composition. Layers  of  such  ore  however  occur  in  the  slates 
above,  resting  on  tight  clay  strata  which  formed  subordinate 
drainage  planes.  In  only  one  place  was  the  ore  changed  to 
magnetite;  a  band  from  one  to  three  inches  thick  is  full  of 
beautiful  small  octahedral  crystals  of  magnetic  iron  ore. 

Dr.  Frazer  says  that  the  general  appearance  of  the  Chest- 
nut Hill  mine  is  that  of  all  the  banks  of  York  county  along 
the  slate  belt,  but  on  a  much  larger  scale;  the  ores  being 
in  all  of  them  of  two  kinds :  (1)  Wash  ore,  distributed 
through  the  upper  part  in  planes  but  without  the  regular- 
ity of  a  bed  of  sediment,  i.  e.  concretionary  shot,  balls  and 
chuncks  embedded  along  rude  planes  of  clay ;  (2)  Solid 
concretionary  ore,  usually  low  in  the  mine,  hard,  massive, 
usually  darker  and  more  botryoidal  or  bunched  like  grapes. 
Quartz  fragments  are  seen  sticking  out  of  the  slope  walls. 

*"A11  the  ores  which  lie  above  the  Chikis  quartzite  from  the  mouth  of  the 
Chikiswalunga  through  Silver  Spring  and  to  the  German  settlement  and  the 
works  of  the  New  York  Company  should  be  included  are  parts  of  the  same 
system."  Frazer,  Report  C3,  p.  203.— The. /Shirk  bank  is  north  of  Chikis 
ridge  3  miles  N.  of  Columbia  and  E.  of  Marietta.  It  produced  8000  tons  a 
year  for  ten  years,  afterwards  less  ;  at  first  4  tons  of  ore  to  one  of  wash,  later 
1  ton  of  ore  to  four  of  wash.  It  was  an  exceptionally  rich  pot,  very  wet, 
slate  clay  mass,  required  heavy  timbering.  No  quartzite  seen.  Limestone 
exposed  in  the  wall.  Grade  of  ore  40%  to  48%.  Stopped  1874.— Coppen- 
hoffer's  and  Garber'sare  small  banks  along  the  same  north  foot  of  Chiques 
ridge,  following  the  fault. 


IRON  MINES  IN  THE  PRIMAL  UPPER  SLATE.     209 

Hollow  bombs  of  ore,  sometimes  tilled  with  very  soft  fine 
clay  or  simply  with  water  and  lined  inside  with  black  oxide 
of  iron,*  are  common. 

Until  the  introduction  of  the  Lake  Superior  Marquette 
and  other  red  hematite  ores  Pennsylvania  easily  held  its 
preeminence  as  the  great  iron  smelting  state  of  America 
by  reason  of  the  great  number  and  remarkable  size  of  its 
brown1  hematite  (limonite)  iron  deposits  ;  and  by  importing 
the  richer  magnetic  and  specular  ores  for  mixing  with  its 
own  stock  of  limonite  and  fossil  iron  ore  it  still  re-mains 
the  principal  iron  state,  furnishing  always  about  one-half 
of  all  the  iron  produced  in  the  United  States.  She  was  the 
first  to  adopt  Bessemer' s  process  of  making  low  steel  in  2, 
and  afterward  5  and  10  ton  flasks,  f 

Most  of  the  great  limonite  beds  are,  as  has  been  said 
above,  in  the  Upper  Primal  slates.  Others  are  in  the  lime 
slates  above  the  Trenton  limestone  No.  lie.  Others  are  in 
the  slates  interbedded  in  the  great  limestones.  Others  are  in 
the  slates  over  the  Oriskany  sandstone  No.  VII.  These 
will  be  described  in  their  proper  places. 

The  Upper  Primal  Slate  limoidtes  range  along  the 
north  side  of  the  Chester  county  valley  ;  along  the  hydro- 
mica  belt  in  York  and  Lancaster;  along  the  north  foot  of 
the  Highlands  from  Easton  to  Reading,  and  along  the  north- 
west foot  of  the  South  Mountains  from  Boiling  Springs  to 
Mont  Alto.  It  is  probable  that  this  is  also  the  geological 
horizon  of  Pine  Grove  mines  on  Mountain  creek  in  the 
heart  of  the  South  Mountains ;  and  possibly  of  the  Rich- 
mond ore  bank  in  Path  Valley  north  of  Mercersburg  in 
Franklin  county,  although  this  last  range  is  along  the 

*This  lining  is  often  oxide  of  manganese,  a  metal  constantly  accompanying 
iron  in  limonite  deposits ;  often  beautifully  crystallized  in  fibers  or  needles. 
The  bombs  and  balls  show  plainly  enough  that  the  peroxide  of  iron  was  dis- 
tributed as  fine  particles  throughout  the  plastic  clay,  and  that  these  particles 
slowly  concentrated  around  points  of  mutual  attraction,  probably  in  most 
cases  towards  minute  quantities  of  organic  matter  which  have  disappeared 
by  oxidation. 

f  A  process  virtually  invented  and  practiced  by  Wm.  Kelly  at  his  furnace 
in  Kentucky,  when  he  boldly  blew  air  into  the  molten  metal  in  his  furnace 
hearth.    See  my  Iron  Manufacturers'  Guide,  1858. 
14 


210  GEOLOGICAL   SURVEY   OF  PENNSYLVANIA  . 

Path  Valley  fault,  on  the  contact  of  the  limestone  with  the 
Hudson  River  slates  ;  as  described  in  a  future  chapter. 

Chester  valley  Umonite  mines. 

The  mines  of  the  Chester  county  valley  have  never  been 
of  first-class  importance.  Prof.  Rogers'  description  of  them 
in  1858  was  condensed  and  re-published  in  C4,  1883,  pages 
141,  etc.  It  has  hardly  more  than  a  historical  value, since  the 
change  in  the  iron  industry  has  concentrated  the  iron  works 
and  destroyed  local  small  mining  by  the  importation  of  dis- 
tant richer  ores.  But  it  has  a  geological  value  for  those 
who  study  our  formations. 

Some  of  the  old  banks  are  on  the  edge  of  the  valley,  and 
evidently  in  the  Upper  Primal  slates,  above  the  sandstone 
and  beneath  the  limestone.  Others  are  as  evidently  wash- 
ings from  these  iron-bearing  slates  into  ancient  caverns  in 
the  limestone,  the  roofs  of  which  have  been  removed  by 
erosion,  leaving  great  pots  of  clay  filled  with  wash  and  ball 
ore.  Of  this  kind  are  the  deserted — 

Hitner  banks  near  Marble  Hall,  Montgomery  countyr 
from  one  of  which  were  taken  10,000  tons  in  1852,  and 
12,000  in  1853.  From  all  the  pits  dug  east  of  the  Schuylkill 
up  to  1858  probably  60,000  tons  were  taken,  in  a  belt  seven 
miles  long  and  a  mile  wide.  The  ore  deposits  ranged  in 
long  narrow  strips,  as  deep  troughs  of  iron  soil  sunk  in  the 
limestone  outcrop  ;  the  two  most  productive  being  one  just 
north  of  the  Barren  Hill  range  ;  the  other  just  north  of  the 
belt  of  marble.  But  outliers  were  found  ;  as,  Wood's  pit, 
one  mile  north  of  Marble  Hall,  where  shallow  ore  soil  rested 
on  limestone  so  thin  that  the  North  Valley  Hill  sandstone 
was  struck  beneath  it.f 

West  of  the  SchuylTcill  several  pits  were  made  south  of 
Bethel  Hill  (Whitehall's  pit,  Fisher's  pit)  for  Merion  fur- 
nace use. 

The  Baptist  Church  old  shaft,  75'  deep,  got  superior  ore, 
resting  on  white  marble.  Another  pit  was  sunk  200'  feet 
further  east. 

t  See  C.  E.  Hall's  Report,  C.  6. 


CHESTER  VALLEY   LIMONITE   BANKS.  211 

Fisher  (Geo.)  bank,  300'  N.  E.  of  Henderson's  marble 
quarry  in  U.  Merion,  is  large,  and  until  1854  yielded  good 
ore  ;  afterwards  more  of  an  earthy  wash  ore. — Another  pit, 
1250'  N.  E.  of  the  last,  and  a  later  pit  for  the  Phoanixville 
works  gave  $  ore. 

Widdart's  bank,  800'  S.  of  last,  was  reopened  before 
1854. — Millerton's  bank  near  the  school  house  sent  ore  to 
Jones'  furnace  above  Conshohockin. — Otto's  bank,  newly 
opened  in  1854,  had  £  ore. — Supple' s  &  Hampton's  pits 
were  small.  Hughes  &  Jones'1  pits  were  also  small,  but 
made  a  large  group. 

Howellville,  Tref.  town,  had  its  group  of  pits  from  which 
good  ore  was  got. —  Wilson's,  N.  W.  of  village. —  Wood- 
man''s  had  ore  f,  dirt  £;  sent  to  Phcenixville. —  Jones', 
Beavers' ,  &  Bucks  and  King's,  near  the  Baptist  Church  £ 
m.  from  Centreville,  were  all  three  large  banks. — 8.  Bea- 
ver's bank,  £  mile  S.  E.  of  head  of  Valley  Forge  dam,  lay 
along  the  north  side  of  the  valley,  and  got  its  ore-wash 
(Rogers  thought)  from  the  lower  magnesian  part  of  the 
great  limestone  formation. — Holland' s  bank,  1£  m.  N.  W. 
of  Howellville,  43'  deep  in  1854,  sent  excellent  ore  to  Pho3- 
nixville. 

West  of  Paoli  was  another  group  of  diggings  :  Buchan- 
an's, 1200'  N.  of  Oakland  hotel,  f  ore,  sent  to  Jones'  fur- 
nace.— Jacobs' ,  2  m.  E.  of  Oakland,  and  two  others  £  m.  S. 
of  Ship  tavern. — McGuire'  s,  1  m.  N.  of  tavern  ;  much  good 
ore. — E  cans' ,  f  m.  E.  of  tavern;  much  good  ore. — Neat's 
three  pits. 

An  untried  pit  was  opened  1  m.  N.  W.  of  Downingtown. 

West  of  Coatesville  several  small  pits  on  the  south  side 
of  the  valley.* 

York  county  Umonite  banks. 

The  mines  of  York  and  Adams  county  in  the  hydromica 
(Upper  Primal)  belt  are  described  by  Prof.  Frazer  in  his 

*  Rogers'  Geol.  Pa.  1858,  pp.  217  to  219,  gives  some  very  interesting  details 
of  Lancaster  Co.  limonite  banks  in  evidence  of  his  belief  that  the  South 
Valley  Hill  mica  slates  (bearing  iron)  underlie  the  Chester  Valley  limestone 
formation. 


212  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

Report  of  Progress  C,  1876.  On  pp.  5  to  9  is  given  a  list  of 
158  mines  in  all  the  formations  of  the  two  counties,  in  alpha- 
betical order,  many  of  them  small  openings,  others  old,  large 
and  deep  mines.* 

Golin  bank  (67)  2  miles  W.  of  Wrightsville,  at  the  N. 
edge  of  limestone  belt,  S.  edge  of  slate  belt ;  opened  1854  ; 
in  1874,  400'  long,  25'  deep  at  west  end,  in  sandy  clays; 

B.  StricJcler  bank.  1  mile  west  of  the  Gohn,  on  the  same 
line  ;  1854  ;  worked  by  Mnsselman  ;  then  by  Haldeman  till 
1864  ;  1874  abandoned  ;  half  an  acre  ;  30'  deep  to  water. 

Stoner  bank,  half  a  mile  further  west  on  same  line  ;  1850 
to  1873,  40,750  tons  to  Musselman  and  Watts ;  partly  by 
shafts  ;  open  f  acre,  25'  deep. 

D.  Rudy 's  banks,  half  a  mile  further  west  on  same  line  ; 
1862  to  1870,  9,872  tons  ;  H  acres,  25'  deep  ;  abandoned. 

Ruby1  s  bank,  half  a  mile  (4£  m.  from  Wrightsville)  on 
same  line ;  1862  ;  worked  4  years ;  400'  long  E.  and  W.  or 
%  acre  ;  abandoned  ;  much  loose  qnartzite. 

Keller's  bank,  half  a  mile  further  west;  £  acre ;  10'  to 
water ;  ore  exhausted. 

Heistand's  bank,  a  mile  further  west  on  same  (midway 
between  Wrightsville  and  York ;)  1864 ;  Musselman  & 
Haldeman  ;  2  acres,  600'  long,  20'  deep  to  water  ;  abandoned 
1871  ;  walls,  clay  and  gravel. 

Blessingef  s  bank,  one  mile  further  west ;  and  1000'  N. 
of  limestone  limit;  £  acre;  trench  750'  E.  and  W. ;  exhausted; 
sandstone  fragments  and  sandy  slate. 

Norses  bank,  half  mile  further  west,  and  J  m.  N.  of 
limestone  ;  f  acre,  300'  long,  25'  deep  ;  abandoned. 

Miller's  bank,  one-third  mile  further  west,  and  2000'  N. 
of  limestone  ;  i  acre,  15'  deep  ;  has  only  yielded  300  tons  ; 
ground  strewn  with  sandstone  and  slate  blocks. 

*  Of  these  are  described  126,  arranged  in  nine  lines  running  N.  E.  and  S. 
W.  and  numbered  from  N.  E.  to  S.  W.  Nos.  1  to  6,  from  Shrewsberry  to  the 
Maryland  line ;  7  to  14,  S.  of  Margaretta  furnace,  from  Red  Lion  to  8.  of 
Jefferson  and  Loganville  to  Red  Lion  ;  15  to  66,  from  S.  of  Wrightsville  by 
Hanover  Junction  to  Littlestown  in  Adams ;  67  to  109,  from  Wrightsville 
through  York  to  N.  of  Hanover  in  Adams  ;  111  to  118,  a  group  north  of  York  ; 
110,  near  the  river  N.  of  Wrightsville  ;  119,  120,  S.  of  Wellsville  ;  121,  W.  of 
Wellsville :  122  to  126,  near  Dillsburg.  In  this  chapter  only  those  in  the 
hydromica  slate  belts  will  be  noticed. 


YORK   COUNTY   LIMONITE   BANKS.  213 

S.  and  1.  Deitz's  two  banks,  £  m.  apart,  further  on,  1500' 
N.  of  limestone  ;  about  1864  ;  abandoned  1870  ;  yielded  2000 
tons ;  8'  stripping  over  ore  lying  in  pockets  in  white  and 
yellow  clay  ;  in  all  \  acre,  20  '  deep  ;  water  scarce. 

Susanna  Fritz' s  bank,  a  mile  west  of  Norse  bank  (.or  3£ 
m.  east  of  York)  and  \  m.  N.  of  limestone  border ;  1865,  to 
June,  1874 ;  principally  wash  ore,  in  pockets  and  nests  in 
blue  clay  which  prevailed  in  the  walls  beneath  the  strip- 
pings  ;  abandoned,  but  large  quantity  of  ore  at  north  end 
reaching  nearly  to  the  surface  ;  40'  deep,  partially  filled 
with  water  (1874.)* 

HeidelsbacTi 's  bank,  f  mile  further  west  and  500'  north 
of  the  limestone  ;  small ;  600  tons  ;  exhausted  by  1868 ;  £ 
acre,  10'  deep.f 

Ifibert  banks,  If  miles  north  of  York  (the  most  northern 
is  sometimes  called  the  Corr  bank).  Operated  by  Benson 
&  Cottrell,  owners  from  1866  to  October,  1873  ;  |+1|  acres, 
30'  deep ;  principally  wash  ore ;  10  tons  daily ;  part  filled 
with  water  (1874)4 

D.  Louck's  banks,  li  miles  northeast  of  York  and  ^ 
mile  north  of  limestone ;  two,  100'  apart,  with  a  smaller 
bank  between ;  1867 ;  wash  ore,  some  lump ;  water  not 
quite  sufficient  to  wash  ;  £  acre,  20'  deep,  and  £  acre,  25' 
deep.g 

Thus  far  the  limonite  deposits  have  been  either  on  or  just 
N.  of  the  northern  edge  of  York  Valley  limestone  belt, 
which  edge  crosses  the  Codorus  a  mile  north  of  York, 
swings  west  and  north  and  east  to  recross  the  creek  two 
miles  lower  down,  and  recrosses  a  third  time  5  miles  north 

*  Many  samples  taken  for  analysis  yielded  in  McCreath's  laboratory : 
Insol.  res.  19.750;  iron  sesquiox.,  63.285  ;  alum.  0.765  ;  manganese  sesquoix., 
2.210;  phos.  acid,  2.986;  sulph.  acid,  0.068;  lime,  0.196;  mag.,  0.216;  water, 
10.880=metaljic  iron,  44.300;  inang.,  1.540;  sulp.,  0.024;  phos.,  1.303. 

f  Here  a  compact  bed  of  quartzite  crosses  the  road,  dipping  60°  northwest, 
but  there  is  room  for  concealed  southeast  dips  between  it  and  the  limestone 
belt. 

J  An  interesting  bed  of  compact  quartzite,  dipping  30°,  north  15°  west  cuts 
out  the  ore  in  the  Corr  bank.  Slates  carrying  ore  much  contorted,  with 
cleavage  planes  dipping  70°  southeast  If  these  be  original  bed  planes  then 
the  slates  dip  beneath  the  limestone. 

§  Rock  beds  cut  are  crystalline  schists  much  intersected  by  veins  of  quartz. 


214  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

of  York.  From  this  third  crossing  the  limestone  edge  runs 
west  2f  miles  to  Ewingsville,  and  so  keeps  on  to  the  north 
side  of  the  Pigeon  hills.  It  then  returns  east,  south,  south- 
west around  the  south  foot  of  the  hills  and  runs  on  into 
Adams  county. 

Returning  now  to  the  Codorus  creek  there  are  several 
banks  in  the  slate  country  north  of  York:  Lightner's, 
Louck's,  Benson  &  Cottrell's,  Hake's,  west  of  the  Codorus ; 
and  Benson  &  Cottrell's  and  Smyser's  east  of  the  Codorus  ; 
all  of  them  either  on  the  limestone  border  or  not  more  than 
1500'  from  it.  Taking  them  in  the  order  named  will  be  to 
follow  the  edge  of  the  limestone  around  Pleasureville.  (See 
Report  C,  1875,  p.  69.) 

Banks  north  of  York. 

Lightness  bank,  1£  m.  W.  N.  W.  of  York,  on  the  lime- 
stone border;  leased  by  an  English  company,  Sept.,  1874. 

LoucTc1  s  bank,  If  m.  N.  of  York,  \  m.  from  the  limestone; 
open  cut  60'  long,  15'  wide,  18'  deep  in  bluish  clay;  stripping 
5';  yellow  clay  with  ocreous  iron,  7';  white  clay  and  chlorite, 
thin;  clay  and  ball  ore  V;  dip  of  slate  46°  N.  23°  W.;  dip 
of  ore  the  same. 

Benson  and  CottreWs  bank,  near  last;  1870;  1000  tons  a 
year;  ten  per  cent,  lump;  water  scarce;  ore  contains  a  little 
sulphur  and  a  little  phosphorus;  magnetic  sand  and  much 
specular  iron  intermixed  with  the  ore. 

Hake's  bank,  %  m.  N.  of  last;  clay;  not  at  work  in  1874. 

Smyser'sbank  (SmaW  s  bank),  3£  miles  N.  of  York,  on 
the  south  edge  of  the  limestone  a  mile  N.  of  PleasureviJle; 
leased  for  20  years  (1864-1884)  by  Ashland  Iron  Co.  2£ 
acres,  40'  walls;  15  tons  per  day  of  both  wash  and  lump 
ore  of  two  kinds,  one  a  sandy  manganese  limonite;  the  other 
a  smooth  greyish  blue  compact  ore  full  of  small  cavities 
stained  on  the  edges  with  limonite;  also  a  white  ore  looking 
like  a  cherty  limestone,  in  fact  a  spathic  or  carbonate  iron 
ore,  suggesting  interesting  reflections  upon  the  genesis  of 
the  limonites.  There  is  on  the  east  side  of  the  bank  a  lime- 
stone bed  which  dips  18°  to  the  west,  i.  e  under  the  ore  de- 


BANKS   NORTH   OF   YORK.  215 

posit,  and  Dr.  Frazer  suspects  it  of  a  greater  antiquity  than 
the  York  valley  limestone.     (See  C,  p.  68.)* 

Cottrell  &  Benson1  s  bank,  across  the  road  from  Smyser's 
bank  ;  1871 ;  10  tons  per  day,  all  wash  ore,  hauled  to 
Emigsville,  railroad  to  Marietta.  In  1874  £  acre,  40'  deep. 
(C,  p.  66.) 

Banks  west  of  York. 

Eisenhart(Jac.},  on  the  Gettysburg  turnpike,  2  m.W.  of 
York,  has  surface  wash  ore  on  slate  ground ;  and  not  far 
from  here  near  the  Carlisle  road  fork  to  Emig's  Mill  in  the 
debris  of  an  old  pit  was  seen  a  large  specimen  of  magnetic 
limonite.  The  Beelor  trap  dyke  runs  across  the  neighbor- 
hood towards  the  old — 

Kauffman  bank,  3  m.  S.  W.  of  York  on  the  narrow  belt 
of  slate  which  from  here  west  to  Pigeon  hills  splits  the 
limestone  belt  into  two  ;  300  tons  were  taken  out ;  ore  so 
magnetic  as  to  disturb  the  surveyor's  compass  ;  ore,  mostly 
anhydrous,  lay  in  scales  along  with  mottled  red  and  blue 
limestone  ;  a  mass  of  ore  in  place  dips  25°  S.  10°  E. ;  but 
the  associated  slates  dip  70°  S.  10°  E.  Beelor' s  trap  dyke 
runs  close  by  on  the  east. 

Ey  ester  s  (M.}~bank(Smysers's,  Brillinger 's  3  m.  further 
S.  W.  along  the  N.  W.  edge  of  the  slate  belt,  along  aban- 
done<J  trench  350'  long,  20'  deep ;  in  fine-grained  mica 
slates  dipping  64°  S.  20°  E.f  Ore  in  nests  and  lumps  of 
brown  and  red  hematite,  but  no  magnetic  visible  under  the 
lens ;  slates  almost  all  weathered  into  white  clay,  with 

*  Careful  sampling,  and  analyzing  by  A.  S.  McCreath,  gives  the  following 
constitution  of  the  first  kind  of  ore : — Insoluble  silicious  residue,  14.78 ;  iron 
sesq.,  46.28;  alumina,  2.67  ;  manganese  sesq.,  22.89;  phos.  acid,  1.49;  baryta, 
1.32;  lime,  0.24;  magnesia,  0. 15 ;  water,  11.20  ;=Iron,  32.40;  manganese, 
15.93;  sulphur,  0.03 ;  phosphorus,  0.65.  Cold  short;  and  unlike  any  other 
ore  as  yet  found  in  York  county. — The  Spathic  ore,  analyzed  by  A.  Pearce, 
under  Dr.  Genth  yielded;  ferrous  carbonate,  77.99;  mang.  carb.,  0.45; 
magnes.  carb.,  3.53;  calc.  carb.,  1.43;  alum.,  2.81 ;  sil.,  11.56;  water,  organic 
matter  and  loss  2.23  ;=iron,  37.65. 

f  All  the  dips,  slate  and  limestone  in  this  neighborhood  are  steep  S.  E. 
(See  ore  map  of  survey  on  a  large  scale,  with  all  the  dips  marked,  in  Re- 
port C. )  If  the  slate  belt  be  an  anticlinal,  then  the  dips  next  to  the  northern 
limestone  belt  must  be  overturned,  and  the  slates  at  this  mine  although 
seemingly  over  the  limestone  are  really  under  it,  where  they  ought  to  be. 


216  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

streaks  of  irony  clay  ;  what  is  not  shows  rotten  lamination; 
at  northern  end  of  pit  compact  fine-grained  mica  slate,  over 
which  at  the  south  end  are  100'  of  the  soft  clay  strata 
carrying  the  ore. 

Emig 's  (Sam.)  bank,  3  m.  W.  of  New  Salem,  near  Nash- 
ville, near  S.  edge  of  slate  ;  opened  1872. 

Johnson's  (W.  S.)  pit,  I  m.  W.  of  last ;  1873;  ore. 

Mengis'  (And.)  bank,  1  m.  S.  of  last,  near  N.  edge  of 
southern  belt  of  limestone  ;  1872  to  1874,  3,772  tons.* 

Banks  of  the  Pigeon  Hills. 

Myers'  (Mich.)  a  mile  west  of  last,  1873.—  Roth's  (S.)  a 
mile  north  of  last ;  1873  ;  10'  deep  ;  ore.— Roth's  (&)  I  m. 
S.  by  W.  of  last ;  20'  deep ;  7'  stripping.  These  are  a 
group  in  the  slate  belt. — Miller's  (J.  L.)  f  m.  S.  W.  of 
last;  abandoned. — Bechtel' s  (Geo.)  If  m.  S.  W.  of  Myers'  ; 
opened  about  1868  by  Musselman  &  Watts  ;  abandoned  in 
1873.^—Forry  (G.)  reports  ore  in  mass  in  his  orchard  near 
the  limestone,  5£  m.  N.  E.  of  Hanover. — Boyer' s  (Sam.) 
bank,  %  m.  west  of  last ;  1854  ;  leased  1872  ;  £  acre,  another 
1£  acre,  both  15'  deep ;  ores  In  segregated  shelly,  friable 
masses  in  clays  ;  no  unaltered  slates  seen.  It  is  the  first 
of  a  series  of  closely  neighboring  pits  marking  the  northern 
edge  of  the  slate  belt  leaning  against  the  Pigeon  Hills  and 
running  on  to  the  Adams  Iine4 

Moulk's  (S.)  bank,  5  m.  N.  E.  of  Hanover  ;  1859  ;  in  1870- 
1874  the  Leesport  Iron  Co.  took  out  14  tons  a  day;  incline 
plane  200'  long.§ 

*  Watts  &  Sons,  the  owners,  give  these  figures  and  an  analysis :  Iron, 
39.640;  insoluble,  37.800;  sulphur,  a  trace;  phosphorus,  0.080;  undeter- 
mined, 22.380. 

t  These  last  eight  banks  are  disposed  around  one  of  the  southern  spurs  of 
the  Pigeon  Hills  and  mark  th*e  shape  of  the  spur.  (Frazer  in  C,  55.) 

Jit  must  be  kept  in  view  that  this  slate  belt  keeps  the  limestone  belt  (to 
the  south  of  it)  away  from  the  Chiques  quartzite  mass  of  the  Pigeon  Hills  ; 
therefore  beneath  the  limestone. 

§  One  hundred  and  eighty  to  one  hundred  and  eighty-five  car  loads  per 
day  (14  tons)  worth  $2.50  per  ton  at  Kauffman's  siding  on  Hanover  Branch 
RR.,  3  miles  distant.  One  hundred-paddle  lump  washer  and  sand  washer  ; 
35  horse  power  engine  consuming  1100  pounds  coal ;  19  men  in  three  gangs  ; 
f  1.00  per  day  wages  ;  or  f  1.50  if  paid  7  to  ~l\  cents  per  car  load  ;  engineer,  |33 


PIGEON   HILLS   BANKS.  217 

MouVs  (Sol.}  bank,  %  m.  west  of  last ;  1854  ;  2£  acres,  15' 
deep  ;  tenaceous  clay  under  stripping  ;  engine  house  at  N. 
E.  end  ;  idle  in  1874. 

MouC  s  (P.)  banks,  (two,)  small. 

BechteVs  banks  ;  (I)  4  acres ;  (2)  J  acre. 

Haldeman  &  Co.'s  bank;  near  the  last ;  1870  ;  £  acre ;  8' 
stripping ;  -f  wash  ore  in  yellow  and  blue  clays  ;  ore  bands 
V  to  3'  thick  irregularly  running  out ;  used  at  Chiques  to 
mix  with  Cornwall  ore  ;  25  tons  per  day  ;  pit  45'  deep  ;  water 
supply  deficient.  Analysis:  Iron  43.00 ;  manganese  3.88; 
sulphur  0.09  ;  phosporus  0.67.* 

Miller' s  (Ashland  Co's)  bank,  400'  W.  of  Kaufman's  (3 
m.  N.  N.  E.  of  Hanover)  and  at  the  base  of  the  Pigeon  Hills; 
1863;  3i  acres;  15  men;  18  tons  per  day  without  incline  plane; 
all  the  blue  and  yellow  clay  mass  contains  paying  mass  ore; 
mixed  with  tremonium  ores  in  the  Ashland  furnace.  Ban- 
man's  bank,  not  far  west  of  last;  \  acre;  stopped  1873. 
Miller  (  Widow)  bank,  near  last,  small.  Porter  (Gov.)  bank; 
1840  to  1862;  shut;  1  acre.  GUI's  bank-,  several  pits  in 
quartzite  and  sandy  slates,  3  m.  N.  of  Hanover;  much  ore; 
abandoned. f 

Banks  near  Hanover. 

'  The  above-described  banks  are  ranged  along  the  foot  of 
the  Pigeon  hills  north  of  the  York  limestone  belt.  South 
of  the  limestone  there  is  no  such  range  of  banks  in  the 
hydromica  slate  country  ;  but  there  are  four  at  Hanover, 
and  two  four  miles  northeast  of  Hanover  of  considerable 

per  month ;  foreman  $40 ;  11  working  hours ;  400  tons  a  month  extracted ; 
two  35  horse-power  boilers  ;  5  cars  in  use  ;  water  for  washer  pumped  from 
mine  ;  12  tons  of  ore  per  day  washed  ;  transport  to  siding  60  cents  per  ton, 
contract  wagons  belonging  to  contractor ;  9  men  always  mining ;  stripping 
9'  ;  under  this  white  clay  and  gravel ;  then  j^ellow  ore  clay,  no  bottom  yet. 
(Report  3,  1874,  p.  59,  here  quoted  as  specimen  of  its  statistics.) 

*  See  full  analysis  in  C,  p.  61.  A.  plate  of  "  red  oxide  "  runs  S.  W.  towards 
Kauffman's;  analysis:  Iron  sesq.,  72.14;  alumina,  1.72;  manganese  sesq., 
0.39 ;  phos.  acid,  0.43  ;  sulp.  acid,  0.12  ;  lime,  0.17  ;  magnesia,  0.33  ;  water,  5.76  ; 
insol.  sil.  residue,  19.09  ;=Iron,  50.50.  This  tough,  hard  siliceous  kind  of  ore 
is  found  elsewhere  in  the  county. — Kaufman's  bank,  next  the  last,  started 
1874. 

fMcConaughy's  exploitation  pits  in  quartzite,  3^  m.  N.  W.  of  Hanover, 
1874,  has  begun  to  show  fairly.  ThiS'«nds  the  series  westward. 


218  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

importance.  The  four  just  south  of  the  village  of  Hanover, 
a  mile  from  the  Adams  line,  are 

Baumann  («/".)  pit,  first  opened  a  century  ago  ;  reopened 
1860  ;  then  leased  by  the  Wrights ville  I.  Co.,  who  took  out 
1000  tons.—  Flickinger' s,  300'  west  of  last;  500  tons  got. 
— Delone  (Louis]  bank,  i  mile  W.  of  Baltimore  pike  ;  1867 ; 
2000  tons  got  in  six  months,  large  and  small  lump  ore  in 
slate  mouldered  to  clay;  slight  stripping;  large  body  of 
ore  seen  (1873)  in  northeast  heading.* — Forney  (A.  M.) 
bank,  400  yards  west  of  last ;  1863  ;  3500  tons  got  and  more 
in  sight,  in  hole  200'  long  by  20'  deep  ;  ore  lumps  in  clay  ; 
abandoned. 

The  two  important  limonite  mines  on  the  south  edge  of 
the  limestone  4  miles  N.  E.  of  Hanover,  are  the  well-known 
Dollinger  and  Sprenkel  banks  : — 

Dollinger  (J.  and  D. )  bank,  leased  by  the  Leesport  I.  Co. 
and  opened  in  1873  ;  180  car-loads  a  day  ;  90  per  cent  wash 
ore;  lumps  and  nests  in  the  clay  of  the  decomposed  slate 
formation.t 

Spr entile*  s  shafts  ;  £  m.  N.  E.  of  last ;  sunk  1874,  north 
of  H.  &  Y.  S.  L.  RR.  Ore  in  first  shaft  peculiar,  dull  brick 
red,  containing  masses  of  specular  and  some  micaceous  ore, 
much  mixed  with  sand  and  the  slate  gangue  (a  fine-grained 
chlorite  hydromica  slate  with  thin  intercalations  of  lime- 
stone}. Two  veins  struck  by  the  shaft,  upper  one  V  thick, 
with  a  thin  roof  of  slaty  limestone.  The  N.  W.  shaft  takes 
out  ordinary  limonite.  Prevailing  dip,  50°  N.  W.  as  if 
going  under  the  valley  limestone.  Further  west,  Mussel- 
man  shaft  struck  solid  ore. 

In  quarry  500'  N.  of  first  shaft  limestone  and  slate  con- 
tact seen,  dip  of  both  48°  N.  35°  W.,  slate  under  limestone. 
This  is  an  all-important  geological  fact,  establishing 

*  Analysis:  Iron,  33.5;  *sulp.,  0;  phos.,  1.47;  silica,  23;  alum.,  27.3;  ox. 
org.,  loss,  14.7.  Another:  Sil.,  8.2;  ferric  ox.,  70.1;  alum.,  .96;  mang.  ox., 
1.75;  phos.  acid,  2.54;  sulp.,  .03;  water,  lB.15;=iron.  49;  mang.,  1.21;  phos. 
1.11.  Another  by  F.  A.  Genth  :  Sil.,  7.55;  ferr.  ox.,  65.6;  alum.,  2. 05;  mang., 
ox.,  7.29;  ph.  acid,  H.05;  water,  13.88;  mag.,  .35;  cobaltic  oxide,  0.22  ;=iron, 
45.9;  manganese,  5.07;  phosphorus,  1.33.  (Report  C,  1874,  p.  41.) 

fSee  statistics  in  C,  p.  55  ;  and  analysis :  Iron  45. 1 ;  manganese,  1.5  ;  sulp., 
0.09 ;  phos.,  0.60. 


SOUTH   OF   THE   YORK   VALLEY   LIMESTONE.  219 

the  location  of  the  ore  in  the  Primal  Upper  Slate  'be- 
neath the  Silurian  (Ordomcian}  limestone,  although  the 
nearest  quartette  is  a  mile  southeast  from  the  ore.^ 

Banks  south  of  the  York  Valley  limestone. 

Before  continuing  this  list  of  mines  into  Adams  county, 
we  will  return  to  the  Susquehanna,  and  note  the  ore  banks 
of  the  hydromica  slate  belt  south  of  the  York  valley  lime- 
stone, beginning  with  the  one  nearest  the  river,  No.  15  on 
the  York  county  map,  C,  page  16. 

Wilton's  ~baiik,  l^m.  S.  of  Wrightsville;  1850;  1855;  1858; 
12,000  tons;  abandoned  before  1874,  but  much  ore  remaining 
65'  beneath  the  surface,  in  a  ravine  between  high  slate  hills; 
limestone  seen  up  the  ravine;  quartzite  marked  on  map. 

Leber  (Dan.}  bank,  2  m.  S.  of  last,  £  m.  back  from  the 
river,  on  the  edge  of  the  limestone;  1872;  mostly  lump  ore, 
concentric  bombs,  the  shells  separated  by  shells  of  clay: 
limestone  1000'  S.  15°  W.  of  the  pit  dips  40°  S.  22°  E., 
therefore  the  north  lip  of  Cabin  Branch  Run  synclinal  lime- 
stone basin  has  the  ore  slates  underlying  the  limestone. 

Emig  (J.)  bank  No.  1,  600'  W.  30°  W.  of  last,  on  the  edge 
of  the  limestone;  stopped  1867. 

Emig  (J.)  bank  No.  2,  £  m.  W.  of  last,  very  old,  aband- 
oned 1869;  shaft  110'  deep;  bottom  ore  so  compact  as  to  re- 
quire blasting;  very  little  wash  ore,  mostly  lump. 

'Keller  (Geo.)  shafts,  1  m.  W.  of  last,  (4  m.  S.  of  Wrights- 
ville); about  1864;  70'  and  30'  deep;  almost  all  lump,  re- 
quiring blasting,  very  near  surface;  in  hydromica  slate 
partly  in  a  very  sandy  slate;  many  pieces  of  quartzite; 
much  of  the  ore  magnetic;  very  crystalline  limestone  close 
by,  dipping  54°  S.  22°  E. 

Burg  (Reuben)  bank,  at  Prospect  (Furnace  P.  O.)  li  m. 
from  Margaretta  Furnace;  shaft  30'  deep  struck  limonite 
charged  with  magnetic  particles. 

Small  (J.)  bank,  ^  m.  W.  of  last;  same  black  ore;  lump 
and  wash  ore  equal;  makes  foundry  iron. 

Margaretta  Furnace  banks,  on  Cabin  Branch  Run,  3  m. 

t  See  the  York  Co.  map  published  in  Atlas  to  Report  C3  on  Lancaster 
county. 


220  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

from  river;  Slay  maker  sold  (1850)  to  Halm  and  Himes,  who 
worked  them  1867  to  1874  (date  of  Report)  at  200  tons  per 
week;  various  limonites  (lurgite,  &c.,)  brittle,  sandy,  shelly 
grading  off  into  slate  rock;  the  purest  ("  black  ore  ")  ana- 
lyzing 60°  iron  seems  to  have  been  subsequently  deposited 
in  cavities  between  the  mica  sla^e  strata,  too  much  decom- 
posed to  show  true  dip;  mines  on  the  contact  of  slate  and 
limestone.* 

A  mile  S.  of  Margaretta  furnace  are  two  banks:  Jas.  Cur- 
rarfs,  opened  about  1844 and  W.  G.  Case's,  about  1851,  from 
which  ore  has  been  mined,  but  they  have  long  lain  idle. 

Keller  (/.)  bank,  If  W.  of  Margaretta  Furnace;  1866; 
JOOO  tons  the  fir,st  six  months ;  then  abandoned  ;  ferrugi- 
nous slates  dip  70°,  S.  20°  E.  .  This  bank  is  within  a  short 
distance  of  the  edge  of  the  phyllite  belt,  therefore  near  the 
bottom  of  the  hydromicas. 

Barcoft s  (Butcher's]  bank,  500'  west  of  last  and  higher 
in  the  same  hydromica  belt ;  opened  1840  ;  work  suspended 
in  1868 ;  ore  cold  short,  plate-like,  hard,  flinty,  tough,  with 
unusual  amount  of  black  glassy  coating,  and  mamillary 
stalactites,  knobs  and  ridges,  which  when  broken  show 
cross-fiber  crystallization  (gothite).  Large  masses  of  lump 
ore  in  the  clay,  regularly  arranged  ;  one  massive  lens  dipping 
30°,  N.  80°  E.  through  the  slates,  which  are  more  or  less 
completely  changed  to  clay ;  upper  part  of  mine  limonite 
and  turgite.  Musselman  &  Watts  took  out  10,000  tons  at 
one  time.f 

Banks  in  the  York  county  pJiyllite  belt. 

Barley  bank,  1  m.  W.  of  last ;  1868 ;  400  tons  in  two 
years  ;  dark  brown  hematite  in  clay,  in  phyllite  slate  belt ; 
i  m.  from  quart zite  belt. 

Hengst  bank,  900'  S.  of  W.  of  last ;  in  same  phyllite  belt 

*See  mining  statistics,  0  p.  20.  Result  of  analysis  of  shell  ore:  iron,  48.8 ; 
manganese,  0.79  ;  sulphur,  0.038  ;  phosphorus,  0.343. 

fSee  mining  statistics  in  C,  p.  22 ;  and  Watts'  analysis :  Silica,  26.75 ;  perox. 
iron,  47.15  ;  alum.,  1.70,  water,  11.40;  undetermined,  13.00  ;=Iron,  33.00.  A 
low  grade  ore  if  this  analysis  represents  the  mine  ;  but  its  siliceous  character 
is  due  to  its  place  in  the  phyllite  formation  instead  of  in  the  upper  hydro- 
mica  formation. 


BANKS   IN   THE   YORK   CO.    PHYLLITE   BELT.  221 

and  as  near  the  quartzite  ;  3,000  tons  in  three  years,  1868  to 
1871  ;  then  idle  ;  15'  deep  ;  ore  a  conglomerate  of  ball  ore 
and  ferruginous  slate. 

Moser's  new  bank,  3  m.  S.  W.,  of  last,  2  m  S.  E.  of  Longs- 
town,  2£  m.  N.  of  Dallastown,  1  m.  from  edge  of  hydromica 
belt ;  1865  ;  abandoned  ;  poor  ore. 

Ensminger*  s  banks,  10W  and  1700'  S.  W.  of  last ;  1866  ; 
1873. 

Moseys  old  bank,  1  m.  W.  of  last,  \  m.  W.  of  Peach 
Bottom  RR.  near  edge  of  hydromica  belt ;  1820-f-  worked  by 
York  Furnace  Co.  ;  then  J.  A.  Wright  &  Co.;  then  (1850) 
Shoenberger,  Musselman  &  Co.;  then  Musselman  &  Watts  ; 
then  Musselman  &  Sons  ;  42,090  tons  from  1850  to  1873  ;  ex- 
cavation 250  yards  long,  now  abandoned ;  ore  masses  are 
still  visible  in  yellow,  white' and  blue  clays  ;  bottom  strewn 
with  lean  compact  ore ;  lump  and  wash  ore  equal.* 

Williams'  oldbanks  (GladfeUer"1  s),  2m.  E.N.E.  of  Logans- 
ville,  was  not  worked  after  about  1830,  but  an  immense 
amount  of  ore  must  have  been  taken  from  the  numerous 
extensive  deep  excavations  in  the  phyllite  belt  within  about 
a  mile  of  the  hypothetical  limit  of  the  Tocquan  schist  belt. 

BrillliarV s  bank,  1£  m.  E.  N.  E.  of  Logansville,  has  been 
worked  by  Kaufman  for  Columbia  furnace,  and  yielded 
the  same  ores  as  the  next. 

Feigley  bank,  the  S.  W.  continuation  of  the  last,  opened 
by  Musselman  in  1867 ;  up  to  1874  (date  of  report)  yielded 
50,000  tons  of  limonite,  finely  disseminated  through  clay 
at  least  40'  deep ;  10  per  cent  lump,  90  per  cent  wash  ; 
also  a  dark-blue  compact  heavy  clay  ore  ;  also  a  peculiar 
"honey-comb  ore,"  composed  of  minute  plates  of  limonite 
knit  together  like  paper  walls  of  a  wasp's  nest.f 

Moser's  oldest  bank,  200'  W.  of  last. 

*See  statistics  in  C,  p.  24.  One  specimen  was  of  parallel  flat  plates,  united 
by  one  or  other  edge,  space  filled  with  lepidocrocite,  stalactitic  limonite  and 
turgite.  Another  was  botryoidal  coated  with  black  glossy  turgite  (?).  A 
third  was  compact  brown  limonite.  A  fourth  (50  pounds)  showed  all  these, 
and  also  a  peculiar  separated  structure,  the  ridges  being  an  inch  high  uni- 
formally  covered  with  glossy  ore.  Partial  analysis  is  (Watts)  :  Iron,  40: 
silica,  32;  phos.,  1.17;  water,  8. 

t  For  statistics  of  mining  see  C,  page  14,  J.  B.  Britton's  analysis  of  an 
average  sample  :  Iron,  46.08  ;  ox.  19.74;  insol.  sil.  res.,  18.66  ;  water  and  org. 


222  GEOLOGICAL   SURVEY    OF   PENNSYLVANIA. 

Banks  in  the  Jiydromica  belt  south  of  York. 

Leader's  Hill  old  opening,  f  m.  W.  of  New  Paradise; 
slates  dip  84°,  S.  70°  E.  No  ore  showing. 

Hess  bank,  5  m.  S.  of  York,  2  m.  W.  of  Logansville ; 
150'  long,  15' deep  ;  1868  ;  ore  too  sandy;  slates  asbestiform, 
vertical,  strike  N.  20°  E. 

Falkenstine  shaft,  abandoned. 

Meyer's  (B.)  bank,  1200'  N.  W.  of  Gladfelter's  railroad 
station  ;  lean  ore  in  vertical  slate  striking  N.  30°  E. 

Stambach's  shaft,  ±  m.  W.  of  station  ;  in  dark  slates 
holding  crystals  of  micaceous  and  magnetic  ore. 

Gladfelter's  bank,  f  m.  W.  of  station,  10'  deep  in  verti- 
cal slates,  striking  N.  34°  E. 

Geisselman' s  bank,  J  m.  W.  of  railroad  between  Glad- 
felter's and  Seven  Valley  (Smyser's)  stations;  four  small 
shafts  sunk  1870,  in  hydromica  slates  impregnated  with 
iron  oxide. 

Thomas  Iron  Co.'s  banks,  $  m.  S.  W.  of  Smyser's  rail- 
road station  ;  two  banks  and  three  shafts,  £  acre  and  f  acre, 
engine  house,  drifts,  etc.* 

Walters-  bank,  f  m.  N.  of  W.  of  Hanover  Junction  rail- 
road station ;  1872 ;  much  hard  limonite  still  visible  in 
bunches  in  clay  of  decomposed  coarse-grained  slate  ;  f  acre, 
40'  deep. 

Crout'  s  bank,  ^  m.  N.  E.  of  Strickhauser's  station,  Han. 
Br.  RB,.,  800'  along  the  road,  18'  deep  ;  hard,  compact 
sandy  limonite  ;  sometimes  operated. 

Knotwell's  shaft  on  the  York  I.  Co.'s  hill ;  Aug.  1874, 
had  reached  hard  ore  (at  27')  same  as  York  Co.'s  ore. 

mat.,  10.94;  sulphur,  none;  phosphorus,  0.69;  alum.,  1.92;  lime,  0.17;  mag- 
nesia, 0.56;  manganese,  0.33  ;  undetermined,  0.91. 

A  finely  laminated  bluish  limestone  containing  white  crystalline  lime- 
stone scattered  through  it  in  spots  resembling  in  certain  portions  a  calcareous 
conglomerate,  in  others  simply  mottled,  appears  in  both  banks,  and  in  the 
run,  dips  85°,  N.  20°  W.  In  a  quarry' near  by  it  is  so  mixed  with  crystalline 
hydromica  flakes  as  to  mimic  hydromica  schist,  although  containing  78  per 
cent  of  carb.  lime  and  magnesia;  thickness  perhaps  400'.  This  is  an  im- 
portant observation.  (C,  p.  15.) 

*  Statistics  in  C,  p.  27.  Analysis  :  Iron,  51.7  ;  no  sulphur ;  phos.,  0.052 ;  sil. , 
6.0;  alum.,  16.4,  etc. 


BANKS   IN   THE   HYDROMICA   BELT   S.    OF  YORK.        228 

Strickhouser's  shaft,  1,200'  W.  of  last;  1860;  pit  200' 
long  (N.  39°  E.)  30'  wide  and  10'  deep,  has  shaft  in  middle 
10'  deeper. 

KnotweWs  bank,  1600'  N.  of  York  Co.'s  works;  200' 
long  ;  dip  66°,  S.  82°  E  ;  another  slate  exposure  strikes  N. 
20°  E. 

York  Iron  Co.'s  mine,  the  most  widely  known  bank  in 
York  county,  yielding  the  so  called  "Codorus  ore,"  2£  m. 
N.  E.  of  Jefferson  (Codorus  P.  O.),  £  mile  N.  W.  of  the 
RR. ;  opened  by  Musselman  in  1854  ;  worked  almost  con- 
tinuously from  1861  to  1874  (date  of  report)  by  York  I. 
Co. ;  a  hard,  compact  slate  highly  charged  with  micaceous 
and  some  magnetic  ore  ;  10  to  20  tons  a  day.  The  slates  in 
Strickhouser's  ravine  through  a  ridge  100'  high  stand 
vertical.  The  back  bone  of  the  ridge  is  Chiques  quartzite.* 

Sheaffer' s  pit,  %  m.  S.  of  last ;  1867  ;  350  tons;  exhausted. 

Thomas  Iron  Co.'s  old  pit,  1700'  S.  W.  of  last;  1869; 
worked  one  year  and  abandoned. 

Thomas,  Iron  Co.''  s  No.  2,  two  banks  and  a  shaft,  2700'  S. 
E.  of  last ;  1869  ;  30'  deep,  abandoned  ;  layers  of  mica  slate 
between  ore  deposits  ;  dips  45°  to  90°,  N.  45°  W. 

Thomas  Iron  Co.'s,  No.  3,  pits  along  a  100'  line  S.  30°  W  ; 
outcrops  of  mica  slate  further  west  dip  75°,  N.  25°  W. 

Smyser  (E.  O.}  bank,'  1869  ;  £  acre,  15'  deep  ;  idle. 

Hanover  Branch  RR.  open  cut  yielded  considerable  ore. 

Flicking er' s  pits  along  road  just  west  of  Jefferson  ;  1873. 

Schumann"1  s  pits,  3'  to  18'  deep,  through  blue  clay  (de- 
composed slate),  strike  limestone  at  17'. 

Meyers'  (Matt.)  bank,  at  bend  of  RR.,  ^  acre,  1871, 
abandoned ;  800'  N.  of  it  sandy  slates  dip  90°,  strike  N. 
60°  T&.—Nes  Hill  pits,  insignificant. 

*  Statistics  of  mining,  C,  p.  30.  Analyses:  (1)  Soft  ore,  iron,  39.280;  sul- 
phur, 0.007 — (2)  hard  ore,  iron  26.650;  sulphur,  0.005.  Another  analysis: 
Iron,  26.0;  silica,  47.5;  alumina,  8.65.  Another:  Iron,  46.13;  silica,  34.10; 
phosphorus,  0.22.  Another  (white  ore):  Iron,  46.100;  no  sulphur;  phos., 
1.258  ;  silica,  15.000 ;  alumina,  16.000;  undetermined,  21.642.  Average  of  three 
analyses  by  McCreath:  Iron,  34.375;  silica,  32.400;  phos.,  0.378.  Average 
lot  of  samples  sent  to  McCrealh  yielded:  Ferrous  oxide,  0.900 ;  ferric  oxide, 
50.857  ;  mang.  sesq.,  0.103 ;  al.,  1.630 ;  lime,  0.862  ;  mag.,  0.303  ;  sulp.  acid,  0.011; 
phos.  acid,  0.513;  water,  1.690;  residue,  43.425;  =  iron,  36.3  ;  mang.,  0.07  It  phos. 
0.224 ;  sul.,  0.004.  The  long  debate  over  the  so  called  "  Codorus  silicon  steel " 
deserves  no  attention. 


224  GEOLOGICAL   SURVEY   OF    PENNSYLVANIA 

Forrey 's  bank,  200'  long,  30'  broad,  15'  deep';  partly 
washed  shut  (1874);  800  tons  in  1869.  Shaft  (reported)  went 
through  8'  stripping,  60'  solid  ore,  bottom  still  in  ore. 

StambacKs  bank,  1200'  S.  W.  of  last ;  200'  long,  50'  wide, 
20'  deep  ;  1869  ;  800  tons  in  one  summer  ;  ore  coldshort. 

Ti'ones  trial  shafts,  1000'  N.  W.  of  Smith's  station  ;  ore 
found ;  filled. 

RudesilVs  bank,  f  m.  N.  E.  of  Smith's  station;  300' 
E.  12°  N.,  100'  wide,  20'  deep  ;  much  washed  in. 

Mickley's  bank,  \  m.  E.  of  last ;  200'  long,  150'  wide,  30' 
to  40'  deep  ;  f  acre  ,  abandoned. 

Eckert  and  Kauffmart s ;  f  m.  N.  W.  of  Smith's  station  ; 
1869  ;  29,000  tons  up  to  1874  ;  ore  lean,  but  works  easy  in 
furnace,  cold  short,  plenty  still  in  sight  (1874);  stripping  0' 
to  12' ;  at  W.  end  rock  ore  30'  thick  exposed,  in  plates  a 
few  feet  thick  with  clay  partings,  dipping  (average)  50°,  S. 
32°  E.  ;  but  the  general  strike  of  hills  and  ore  banks  is  more 
nearly  N.  75°  to  80°  E.* — -Hartmart s  bank  is  a  continua- 
tion of  it  eastward,  separated  only  by  a  road. 

Stover's  bank  is  close  to  the  Hanover  Branch  RR.,  600' 
N.  W.  of  trial  shaft  at  W.  end  of  last. 

SprenkeVs  bank,  800'  S.  W.  of  last  at  York  Road  RR. 
station  ;  £  acre  ;  1874. 

Kraber  &  Nes1  bank,  500'  S.  W.  of  last ;  1868  ;  f  acre  ; 
1000  tons  first  year  ;  then  Thomas  Iron  Co.  (1870)  10  to  30 
tons  a  day. 

All  these  last  banks  are  on  a  range  through  the  heart  of 
the  hydromica  belt,  near  the  railroad  ;•  but  only  N"o.  54  is 
located  on  the  geological  map  of  York  county. 

Along  the  southern  edge  of  the  hydromica  belt  near  Xenia 
and  the  Maryland  are  Nos.  13,  14.  at  the  limit  of  the 
phyllites :  — 

Hof acker* s  bank,  a  century  old,  7  m.  S.  E.  of  Hanover,  3 
m.  from  the  state  line  ;  a  quarry  of  hardened  chlorite  slates 
(cut  by  quartz  veins,  studded  with  pyrite  and  chalcopyrite) 
nearly  vertical,  striking  N.  20°  E. — 900'  N.  by  E.  from  the 
old  bank  is  the  new  Wrightsville  Iron  Co.  bank  (April, 
1874);  ore  limonite  with  some  magnetite  in  a  regular  bed 

*See  statistics  in  G,  p.  38. 


ADAMS  COUNTY  LIMONITE  BANKS.         225 

hardly  needing  washing  ;  dip  of  schists  in  cut  50°,  S.  70°  E., 
but  in  the  quarry,  90°,  S.  70°  E.—  Benade1  s  shaft  is  f  m. 
S.  W.  of  the  bank. 

Adams  county  limonite  banks. 

McConaughy  trial  pits,  on  the  H.  and  C.  pike,  3£  m.  N. 
W.  of  Hanover,  for  the  Lochiel  works  (1874),  is  the  last  ore 
spot  on  the  Pigeon  Hill  slate  ore  range,  but  in  quartzite 
land.  West  of  this  nothing  is  noted  in  Report  C,  1874, 
p.  64. 

On  the  York  valley  belt  of  slates,  the  range  of  banks  is 
continued  across  into  Adams  county  by  the  following  banks 
(C,  p.  42) : 

Schwartz  (Sam.)  bank,  2  m.  S.  W.  of  Hanover ;  1874 ; 
1000  tons  exhausted  it ;  machinery  standing  ;  ore  in  crystal- 
line slates  dipping  45°,  about  south,  conformably  inter- 
leaved, and  also  cutting  the  slates. 

'Schwartz  (Sol.)  bank,  f  m.  S.  W.  of  last ;  1855  ;  1  acre, 
30',  40'  deep ;  2000  tons  taken  out  in  1872  to  1874 ;  much 
ore  left  in  floor  ;  walls  full  of  wash  ore. 

Boyer  bank,  on  Hanover  and  Littlestown  RR.,  3  m.  N. 
E.  of  Littlestown  ;  1856  ;  f  acre,  15'  deep. 

Lefeme  pits,  H  m.  S.  E.  of  last.  Shaft  20'  deep,  caved 
in,  filled  up  (1874).  A  sandy  yellow  ochre  ("mineral 
paint")  occurs. 

Krumr  em's  pits,  on  S.  slope  of  hill,  f  m.  S.  W.  of  last; 
1870  ;  40  tons  of  35  per  cent,  iron  ore  ;  nothing  visible  (1874) 
but  some  Codorus  ore  slate. 

Early  and  Killing  er"  s  mine,  2£  m.  E.  by  N.  of  Littles- 
town  ;  1874 ;  20,  30  tons  per  day,  one-third  lump  ore  for 
Keystone  furnace,  Reading  ;  2000  tons  to  Marietta;  foundry 
iron  ;  matrix,  mouldered  clay  slate  in  place,  with  three 
cleavage  planes,  with  one  of  which  the  ore  dips  14°,  S.  15° 
W.  Limestone  cut  200'  west  of  bank,*  dips  25°  S.  36°  E., 
and  strikes  N.  54°  E.,  both  uncertain. 

Lefeme" s  (Enoch)  bank,  2  m.  E.  of  Littlestown ;  1869 ; 

*Said  to  carry  lead  ore  {galena).  For  mining  statistics  see  C,  p.  45. 
Analysis:  Iron,  46.9;  manganese,  0.815;  sulphur,  0.11;  phos.,  1.224,  from 
average  specimen.  McCreath. 

15 


226  GEOLOGICAL   SURVEY   OF  PENNSYLVANIA. 

1200'  long,  2|  acres ;   a  50  per  cent  cold-short  wash-ore ; 
idle  from  1871  to  1874,  machinery  standing. 

Clark  (Widow]  bank,  1£  m.  E.  of  Littlestown ;  pits 
stripping  yellow  and  white  clay ;  two  large  pits  1000' 
apart,  the  north  one  (1868)  poorer  ore,  the  south  one  (S 
shaped,  over  i  acre)  partially  filled,  idle  (1874),  machinery 
standing  ;  ore  shelly  like  that  of  the  range.  Limestone  in 
quarry  1200'  north  dips  50°  S.  35°  E.* 

Lancaster  county  Umonite  banks. 

The  Chestnut  Hill  group  of  banks  on  Chiques  ridge  has 
been  described  in  the  beginning  of  this  chapter.  A  full 
description  of  them  will  be  found  in  Dr.  Frazer's  report  on 
Lancaster  (C3,  1880,  page  208  to  220),  as  the  Sherk  (No. 
6)  on  the  map ;  the  Copperihoffer  (No.  7);  the  Hertzler 
(No.  8);  the  Chestnut  Hill  (No.  9);  the  Silver  Spring 
(No.  10) ;  and  the  Gamber  ;  all  of  them  in  the  Upper  Primal 
Slates  above  the  Chiques  quartzite.  Those  which  follow 
are  in  the  chloritic-mica  slate  or  phyllite  country  of 
Conestoga,  Providence,  Eden  and  Bart  townships. 

Grubb  (C.  B.)  banks,  a  mile  N.  W.  of  Colemanville  and  \ 
m.  from  the  river  ;  1834  ?  The  decomposed  schists  near  the 
river  dip  72°,  N.  15°  W.f  Open  cut  130'  into  the  hill ; 
face  50'  high  ;  stripping  6'  to  10';  mostly  wash  ore,  with 
some  lump,  very  like  the  York  county  hydromica  belt  ores, 
ball,  shell,  partly  manganiferous  limonite  with  occasional 
gothite.  The  ore  is  in  layers  between  the  schists,  in  the 
bank  next  the  river  ;  but  solid  in  the  heading  of  the  north 
bank.  The  three  banks  range  N.  20°  W.  650'  long  in  all. 
Many  bombs  filled  with  steel  gray  ore4 

Good? s  bank,  f  m.  E.  of  Safe  Harbor  ;  abandoned  ;  black 
magnetic  sand  strewn  along  the  road  ;  as  also  near  the 
foot  of  the  hill  by  Colemanville. 

*In  Report  C2,  page  C  201,  202,  a  little  further  information  is  given  re- 
specting the  ore-producing  chlorite-hydromica  belt  south  of  Littlestown  to 
the  Maryland  State  line. 

f  Finely  laminated  gneiss  near  by  dips  the  same. 

JJ.  B.  Britton's  analysis  found:  Iron,  53.59;  ox.,  20.42;  water,  11.76;  sil. 
matter,  10.08;  soluble,  0.66;  sulphur,  none;  phosphorus,  0.44;  ox.  with 
phos.,  0.57  ;  alum.,  0.64;  lime,  0.22;  magnesia,  0.04. 


LANCASTER   COUNTY    LIMONITE   BANKS.  227 

Reeves  &  Co.  banks,  330'  N.  E.  of  the  first  Grubb  bank ; 
abandoned,  1866. 

Shenk  (M.  R.)  banks  ;  opened  before  1840  ;  4  or  5  acres  ; 
abandoned ;  are  lean  and  shelly;  dip  in  mouldered  mica 
schist  and  hydromica  slate,  50°,  N.  15°  W. 

Peacocks  mine,  in  New  Providence,  back  of  Groflfs 
hotel;  1874;  65'  by  50',  and  35'  deep,  fallen  shut  (1877); 
ore  in  laminated  gneiss  full  of  iron,  flat  balls,  not  magnetic.* 

Mowzer  s  mine,  £  m.  S.  W.  of  last ;  1867  ;  cut  N.  E. — S. 
W.  500'  long,  70'  wide,  35'  deep  ;  walls  of  white  and  red 
clay  ;  ore,  limonite  balls  in  very  quartzose  gneiss ;  large 
lumps  of  good  ore  and  milk  white  quartz  strewed  along 
the  road. 

Eckman  &  Patterson's  pit  No  2,  nearly  1  m.  S.  E.  of 
last ;  1867 ;  new  mine  worked  in  1877  for  Port  Kennedy 
Furnace ;  limestone  (struck  at  50')  highly  crystalline  and 
micaceous. — Pit  No.  2,  |  m.  E.  of  last ;  1  acre;  mass  of  ore 
in  north  end  (50'  high);  dip,  35°,  N.  15°  west ;  ore,  as  crusts 
of  limonite  on  prisms  of  laminated  gneiss,  filled  with  grey 
micaceous  sand. 

Geiger's  bank,  not  far  S.  E.  from  last  ;  1857 ;  once  yielded 
20  tons  daily,  for  furnace  in  Lancaster  ;  ore  excellent,  thick 
and  compact,  in  some  places  loose  ;  was  to  start  again  July 
1877  (Report  C3,  p.  228). 

Cook,  WrigJit  &  Co.'s  mine,  worked  before  1776  for  the 
old  Mill  Valley  furnace  ;  bought  by  Cook  &  Wright  1867, 
who  took  out  20  tons  per  day,  all  wash  ore  but  £  lump. — 
Geo.  Bear's  and  SJientf s  banks  adjoin  on  the  west. — 
Brooks'*,  Montgomery  and  Reading  RR.  banks  lie  still 
further  west.  Geiger  &  Baer  took  out  40,000  tons  ;  ore  in 
bottom  too  solid  to  pick  and  not  solid  enough  to  blast. 

Myers  (B.  B.)  bank  in  Eden  township. 

Smith  (Stewart)  bank,  |  m.  E.  20°  N.  from  last. 

Lefecre  (Dan.)  bank,  %  m.  N.  of  Quarry ville  ;  20  tons  a 
day  ;  10  per  cent.  lump. 

Cabeen  &  Co.  bank,  just  N.  of  Camargo  ;  worked  by  Jas. 
Hopkins  for  30  years  ;  25  tons  per  day  for  last  two  years 
(1877);  ore  once  hauled  5£  m.  to  Conewingo  furnace  ;  iron 

*  Reported,  magnetic  ore  found  in  pit  \  m.  N.  E. ;  gneiss. 


228  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

greatly  praised  by  Admiral  Dalgren  for  naval  ordnance  ; 
pit  1000'  long,  100'  broad  ;  full  of  water  (1877).* 

Meyers  (B.  J.)  bank,  on  Keens  run,  Eden  township  ;  1835  ; 
worked  1873,  1874,  at  15  tons  a  day  ;  ore  same  as  Cabeen's  ; 
25  per  c.  lump. — Peacock  and  Thomas  bank. — Brooks 
bank,  old,  same  range  and  i  m.  W.  of  B.  B.  Myers  ;  1835±  ; 
worked  for  twenty, years. — Eckert  &  Go.  mine,  1  m.  E.  of 
Quarryville. — Eckert  &  Hensel  bank,  H  ni.  N.  N.  E.  of 
Quarryville  ;  old  ;  1830±  for  Mt.  Eden  Furnace. 

Herr's  bank,  1  m.  N.  W.  of  New  Providence,  on  the  edge 
of  the  limestone,  just  north  of  the  Lancaster  and  Quarry- 
ville RR.  ;  1852 ;  1000  tons  per  year  for  the  Phoenixville 
Furnaces. 

Mylin  bank,  2  m.  N.  W.  of  last  in  the  limestone  region. 
(See*C3,  p.  236.) 

Welsh  mountain  banks. 

In  Caernarvon  township  of  Lancaster  county  just  north  of 
the  Chester  county  line,  and  on  the  north  slope  of  the  Welsh 
mountain  facing  the  hydromica  slate  ridge  at  the  south  edge 
of  the  Conestoga  valley,  are  a  row  of  limonite  iron  mines, 
excavations  in  debris  mainly  composed  of  fragments  of 
quartzite,  the  disintegrated  grains  of  which  compose  the 
subsoil,  in  which  the  iron  set  free  has  collected  into  brown 
and  red  hematite  ore  in  deposits  of  white  and  pink  clays 
lying  upon  the  solid  quartzite  strata,  as  at  the  Chestnut 
Hill  mines  near  Columbia  described  at  the  beginning  of 
this  chapter.  The  ores  are  in  the  Upper  Primal  slate  forma- 
tion. 

Shirk's  bank,  1£  m.  S.  S.  E.  from  Church  town ;  leased 
1872  ;  worked  to  1876,  at  25  to  30  tons  per  day  ;f  ore  in  nests 
and  pockets  ;  in  limestone  slates,  no  other  rock  visible.:}: 

*See  valuable  mining  statistics  for  this  and  the  banks  preceding  and  sue-' 
-ceeding  in  C,  p.  231  <fec. 

f  See  full  account  of  force,  machinery  &c.  in  C3,  p.  239. 

t  A  drift  100'  long  driven  S.  into  the  mountain  filled  with  water  during  Sun- 
day ;  on  Monday  a  hole  opened  in  the  floor  of  the  drift  50'  from  entrance  into 
which  all  the  timbering  fell,  apparently  into  a  cavern  in  limestone.  Dr. 
Frazer  supposes  the  ridge  in  front  of  the  mountain  to  be  anticlinal  making 
a  south  dip  at  the  mines.  C,  p.  240,  241. 


WELSH   MOUNTAIN   LIMONITE   MINES.  229 

McKay's  mine,  \  m.  S.  by  W.  of  last;  1876  ;  small. 

Slolzfuss  opening,  a  little  S.  W.  of  last ;  a  few  tons  ex- 
tracted.— No  exposures  for  2  miles  further. 

Shirley's  bank,  near  Shirk's  bank  ;  2  acres  ;  depth  60'  in 
south  heading ;  stripping  30'  of  white  and  pink  clay  ;  in 
bottom  a  great  square  shaft  reaches  dark  brown  and  black 
ore  like  that  which  at  Chestnut  Hill  immediately  overlies 
the  quartzite.  Structure  obscure,  but  apparently  two  syn- 
clinals and  one  anticlinal  and  half  of  another  in  the  length 
of  the  bank.  A  pit  20'  deep  rapidly  filled  with  water  ;  30' 
of  drilling  then  went  through  dry  black  powdery  ore. 

German's  bank,  150'  E.  and  W.  and  50'  broad ;  clay  dip- 
ping 20°,  N.  16°  W.  ;  full  of  water  ;  much  black  lump,  man- 
ganiferous,  left  lying  about ;  soil,  clay  and  quartz  gravel. 

Smith  &  Sons  'bank  ;  \\  acres  ;  40'  deep  to  water ;  plane 
steep  ;  machinery  standing  (1876) ;  dip  apparently  45°  N. 
but  very  uncertain. — Beartown  old  mine ;  1861. 

Beartown  new  mine  ;  1873  ;  2£  acres  ;  250'  long  (N.  and  S.) 
and  170'  broad ;  S.  E.  dip  in  the  S.  heading  soon  rolls  over 
to  a  gentle  N.  W.  dip  continuing  to  N.  end  of  mine.* 

Sens  inning  bank,  ad  joins  last  on  W.  ;  1875  ;  20  tons  a  day. 

Russel  bank,  close  to  last ;  1870  to  1877  continuously  at 
25  tons  per  day  for  Seyfert  &  McManus  (like  the  last) ;  i 
lump,  f  wash  ore. 

Garmarts  bank ;  1875  ;  Levi  B.  Smith  ;  30  to  40  tons  of 
limonite  per  day;  £  lump  ore.f 

Northampton  county  limonite  mines. 

The  limonite  mines  of  Northampton,  Lehigh  and  Berks 
have  been  described  by  Prof.  Prime  in  his  Reports  of  Pro- 
gress D,  D2,  and  D3,  Vol.  I. 

In  these  reports  the  Chiques  quartzite  is  always  called 
Potsdam  sandstone. \ 

*  Copious  mining  statistics  given  in  C3,  p.  244. 

fFor  the  Warwick  and  other  mines  in  N.  Chester  Co.,  and  the  Jones  and 
other  mines  in  S.  Berks  Co.,  the  reader  is  referred  to  a  subsequent  chapter  ; 
as  their  geological  place  is  not  fixed,  thay  shall  be  grouped  with  the  Dills- 
burg  mines  of  York,  etc. 

JThe  following  description  of  the  rockoughtto  have  been  quoted  in  Chap- 
ter XVI,  page  179.— The  quartzite  outcrop  extends  from  E.  Penn  RR.  June- 


230  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

The  Upper  Primal  or  hydromica  slates  overlying  it  are 
always  called  by  Prof.  Prime  damourite  slates.  These 
form  the  lowest  division  of  the  Magnesian  limestone  series 
(the  Calciferous  sandstone  formation  as  it  is  known  in  New 
York),  containing  extremely  variable  percentages  of  the 
carbonates  of  potash,  soda,  lime,  magnesia  and  iron ;  and 
they  moulder  away  at  the  surface  of  the  ground  (and  as  far 
beneath  the  surface  as  the  rainwater  penetrates  the  earth) 
into  white  and  tinted  clays  holding  the  concentrated,  oxi- 
dized and  hydrated  iron  in  the  shape  of  ball  ore,  which  at 
the  bottom  is  often  a  solid  mass,  and  occasionally  crystal- 
lized into  pipe  ore.* 

tion  (with  one  interruption)  all  the  way  to  S.  Bethlehem.  It  is  a  hard  com- 
pact rock  of  greyish  tint,  weathering  yellowish  from  the  iron  it  contains. 
Small  dots  and  specks  of  weathered  out  felspar  make  it  pockmarked.  Its 
total  thickness  measured  at  one  place  is  only  21'.  At  C.  Raw's  opening 
(close  to  RR.  track)  it  lies  conformably  on  the  gneiss,  for  a  short  distance, 
thus : — sandstone  ;  under  this,  damourite  slate  with  a  little  magnetite,  only 
2  inches  ;  then  distinctly  bedded  gneissic  rock,  only  18  inches;  then,  gneissoid 
rock  with  mica  and  partly  altered  hornblende ;  then  hornblende  rock  de- 
composed to  a  sort  of  serpentine ;  then  normal  syenite.. —A  little  further 
east,  the  upper  beds  are  typical  quartzite  ;  the  lower  beds  a  conglomerate  of 
rounded  quartz  pebbles  from  the  size  of  a  man's  head  to  a  hen's  egg,  or 
smaller,  often  with  fragments  of  perfectly  fresh  dark  red  orthoclase  felspar  : 
also  well  preserved  scolithus  linearis  (worm-burrow  casts).— Eastward,  it  is 
typical  quartzite,  until  at  S.*Bethlehem  red  shale  (much  like  Trias  shale) 
takes  the  place  of  the  quartzite.— Behind  the  University  it  is  quartzite.— In 
the  RR.  cut  it  dips  N.  W.  unconformably  over  syenite. — East  of  Lower 
Saucon  church  bowlders  mark  its  outcrop,  close  to  syenite. — Further  E.,  on 
the  J.  Bergstresser's  farm,  trial  ore-pits  struck  decomposed  sandstone. — 
Close  to  the  Delaware,  it  is  a  conglomerate  of  nut-sized  rounded  quartz 
pebbles  and  small  pieces  of  felspar,  graduating  upward  into  sandstone,  and 
still  higher  beds  of  the  Calciferous  sandstone.— For  its  other  outcrops  in 
Northampton  county  see  Prime's  Report  D3,  p.  208. — See  also  his  resum6  of 
Fontaine's  sections  in  Virginia,  and  Saftord's  in  Tennessee,  on  pp.  211,  212. 

*  As  a  pure  mineral  damourite  is  essentially  a  hydrous  silicate  of  alumina 
and  potash  ;  and  in  form  it  is  a  hydrous  muscovite  mica,  the  white  (or  silver 
grey)  scales  of  which  make  up  sometimes  as  much  as  one-half  the  body  of 
the  slaty  rock.  One  of  Dr.  Genth's  analysis  of  this  slate  reads  :  Sil.  acid., 
45.57  ;  alumina,  34.83  ;  potash,  10.16 ;  water,  5.30  ;  perox.  iron,  2.94  ;  soda,  0.87  ; 
magnesia,  0.83;  lime,  0.40.  (Report  B,  p.  123.)— In  four  analyses  the  dam- 
ourite mica  made  up  28.39,  49.70,  53.02  and  55.40  per  cent  of  the  slate.— A 
fifth  analysis  showed  phosphoric  acid,  0.102,  and  sulphuric  acid,  0.110,  which 
probably  were  connected  with  the  iron  in  the  specimen  of  slate  (ferric  oxide, 
3.79).— Damourite  slate  has  a  soapy,  unctuous  feel,  is  usually  of  pale  straw 
yellow  to  yellowish  white,  sometimes  pinkish,  and  has  a  pearly  lustre.  It 


NORTHAMPTON   COUNTY   LIMONITE   MINES.  231 

Professor  Prime's  general  description  of  the  limonites  of 
Lehigh  county  will  apply  to  those  of  Northampton  and 
Berks  as  well,  and  to  those  of  Lebanon,  Dauphin,  Cumber- 
land, Franklin,  which  are  but  local  repetitions  along  the 
same  grand  belt  of  valley  limestones,  in  damourite  lower, 
middle  and  upper  slates.  I  give  it  here  in  a  condensed 
shape,  for  convenience.  He  says  : 

The  ore  occurs  massive,  earthy,  botryoidal,  mammillary, 
concretionary  and  occasionally  stalactitic.  It  has  a  silky, 
often  submetallic  lustre  ;  sometimes  dull  and  earthy,  color 
of  fracture  various  shades  of  brown,  commonly  dark,  never 
bright ;  when  earthy,  brownish  yellow,  ochre  yellow.  Stal- 
actites at  the  bottom  of  mines  are  pipe  ore.  Hollow  concre- 
tions are  pot  or  bombshell  ore ;  full  of  water,  or  of  sticky 
clay  ;  inner  walls  glazed  with  oxide  of  manganese.  Solid 
balls  have  cracked  and  honeycombed  cores. — With  the  com- 
mon limonite  sometimes  occurs  scaly-fibrous  or  feathery- 
columnar  mica-like  lepidocrocite  of  yellow,  reddish  or  black- 
ish brown  color,  holding  about  63  per  cent,  of  iron,  but  of 
no  money  value  because  in  such  small  quantity. — Most  of 
the  ore  is  in  pieces  so  small  as  to  require  washing  to  carry 
off  the  clays  in  which  they  are  embedded. 

Ranges  of  Northampton  banks. 

The  principal  range  is  along  the  north  slope  and  foot 
of  the  Lehigh  mountains  facing  Easton  and  Bethlehem. 
Others  are  in  the  small  limestone  valleys  between  the  mount- 
ains. Others  are  in  the  limestone  country  (Formation  No. 

can  rarely  be  got  in  a  perfectly  fresh  condition,  except  in  mines  actively 
worked.  On  exposure  to  the  weather  the  slate  soon  begins  to  decompose 
and  turns  to  unctuous  clay.  This  clay  is  generally  brown  or  yellow  at  first, 
but  in  time  bleaches  white.  The  decomposition  of  the  slate  is  probably  due 
to  the  presence  of  the  potash  and  soda,  and  hastened  by  carbonic  and  humic 
acids  in  the  rain  water.  The  two  following  analyses  of  (1)  a  white  and  (2) 
a  yellow  clay  from  the 'same  pit  are  instructive  :  (1)  Sil.,  72.2;  fer.  ox.,  1.0; 
al.,  21.8 ;  mag.,  0.7  ;  lime,  0.2 ;  soda,  2.1 ;  pot.,  3.0 ;  water,  4.7.— (2)  Sil.,  64.6 ;  fer. 
ox.,  5.6;  al.,  22.8;  mag.,  1.3;  lime,  0.4;  soda,  2.8;  pot.,  3.25;  water,  4.7.— The 
most  notable  difference  between  the  slate  and  the  clay  is  (1)  the  excess  of 
silica  in  the  clay,  on  account  of  the  great  quantity  of  tree  quartz  left  behind 
in  the  mass;  (2)  the  excess  of  iron  ;  (3)  the  great  loss  of  potash,  proving  that 
the  formation  of  soluble  salts  of  potash  is  the  cause  of  the  destruction  of  the 
slate.  (D,  p.  13,  14.) 


232  GEOLOGICAL   SUKVEY   OF   PENNSYLVANIA. 

II)  north  of  the  Lehigh.  Others  are  along  the  north  border 
of  the  limestone  in  a  range  of  damourite  slate  at  the  south 
edge  of  the  great  roofing  slate  country  of  the  Hudson  River 
slate  formation  (No.  III.)  There  is  no  essential  difference 
between  exhibitions  of  ore  in  Northampton  and  Lehigh 
counties  except  in  the  matter  of  quantity;  Northampton 
being  far  behind  Lehigh  in  this  respect. 

The  eight  mines  at  the  foot  of  the  mountain  from  the 
Delaware  river  at  Easton  to  the  Mary  Brotzman  mine  (No 
47  on  the  6- sheet  map  of  the  county,  in  Prof.  Prime's  Re- 
port D3,  Vol.  1,  1883)  are  underground  workings,  on  ac 
count  of  the  very  heavy  stripping  ground  which  would  haye 
to  be  removed  to  work  the  ore  in  open  cuts  or  quarries. — 
These  underground  mines  are:  Seibert's  (two);  Hess; 
Lewer  ;  Glendon  I.  Co.  ;  Woodring  (J.) ;  Miller  ;  Sampson. 
— Then  follow  on  this  range :  Sampson  &  Sitgreaves  ; 
Heckman;  Hahn  (Adam);  Glendon  I.  Co.;  Woodring 
(Enoch);  Hahn  (W.);  Boyer;  Crawford;  Wolf  (R.);  Nolf 
(T.);  Brotzman  (J.  L.);  Brotzman  (Mary,  Nos.  44,  46,  47); 
Jacob;  Richard;  Brotzman  (Mary,  No.  48);  Richard  (T.); 
Lerch.* 

In  the  mountains  are : — Walters  (worked  for  the  Dur- 
ham I.  Co.);  Joy  (Nos.  53,  55);  Raub  &  Lerch;  Stout  & 
Riegel.f 

*  Of  Prof.  Prime's  notes  on  the  Northampton  mines  along  the  foot  of  the 
mountain  I  select  the  following,  from  D  3,  Vol.  1,  p.  194,  etc. : 

Jacob  Crawford,  (No.  43)  2  rn.  S.  W.  of  Easton;  shaft  18'  down  to  6'; 
lump  ore;  interval  ?  60' ;  second  bed  of  ore.— Mary  Brotzman  (No.  44)> 
shaft  64'  to  upper  ore,  4'.— M.  Brotzman  (No.  46),  open  cut,  no  regular  bed; 
alternate  beds  of  dark  brown  and  light  yellow  decayed  damourite  slate ; 
flint  with  the  clays ;  dip,  17°,  N.  72°  E.,  perhaps  conformable  to  surface  over 
which  the  clays  have  washed. — M.  Brotzman  (No.  48),  small  open  cut ; 
little  ore  in  partially  decomposed  slate  ;  W.  end  ore  in  bottom  ;  thin  streaks 
of  manganese  oxide  in  the  face  prettily  crystallized.  (N.  B.— The  miners 
were  carefully  picking  this  out  to  throw  away,  and  were  much  astonished 
to  learn  that  it  was  valuable.)— T.  Richard,  3  m.  S.  W.  of  Easton  ;  open  cut : 
ore  interstratified  between  white  clays  ;  shaft  107'  down  through  slate  and 
clay  to  ore  " 27'  to  40'  thick "  on  a  floor  of  "  black  dirt"  (D3,  Vol.  1,  p.  194. ) 

f  Raub  &  Lerch  (No.  54),  5  m.  S.  of  Easton  ;  shaft  sunk  15'  to  ore,  and 
100'  to  ore;  3  beds  of  ore  reported,  middle  one  only  minable;  partings 
damourite  clays.— Joy  (No.  55),  2  shafts,  50'  and  75'  deep,  to  ore  in  damou- 
rite slate  and  clay.— &t  Stout  &  RiegeVs  abandoned  mine,  5^  S.  W.  of  Easton, 
magnetic  ore  occurs  near  the  limonite  pit. 


a 

: 


LEHIGH   COUNTY   LIMONITE   MINES.  233 

All  the  mines  thus  far  mentioned  are  on  outcrops  of  the 
ower  damourite  slate  formation  at  the  bottom  of  the  great 
imestone  series. 

Mines  north  of  the  Lehigh  river  and  in  damourite  slates 
)f  various  horizons  in  the  middle  and  at  the  top  of  the 
imestone  series  are  thus  named  and  described  in  D3: 
Biery(Jas.);  George  (Ab.);  Chapman;  Lerch;  Shinier  (No. 
|  ))  ;  Ritter  (Simon) ;  Goetz  ;  Gernert ;  Merwin  &  Shortz  ; 
\ohler;  Ritter  (W.);  Schortz  (Nos.  12  and  14);  Hummel; 
3eck  (W.  G.);  Beck  (J.);  Lawall ;  Woodring;  Gernert  & 
leller  ;  Messinger  &  Woodring  ;  Moser  ;  Fogel ;  Young  ; 
5chimer  (No.  24);  Walter;  Richard  (T.,  Jr.);  Messinger. 

Lehigh  county  limonite  mines. 

There  appear  to  be  four  lines  of  ore  deposits  across  Lehigh 
Bounty.  (7)  A  southern  range  along  the  foot  of  Lock 
Ridge,  on  a  general  N.  W.  dip  like  the  rocks  on  which  the 
)re  (and  damourite  slate)  rests.  In  this  range  are  the  mines 
:>f  Wagenhorst ;  Wescoe  ;  A.  Hertzog  ;  H.  Kaiser  ;  Meitzler  ; 
Ludwig,  Hertzog  and  Liess ;  Kreishman  (2) ;  Gaumer ; 
£erschner  (2)  ;  Schwankweiler  ;  Crane  I.  Co.  ;  Allentown  I. 
Jo.  ;  Wiand  ;  Laros  ;  Marck  ;  and  those  at  Hunsingerville, 
tfhich  are  so  grouped  together  as  to  constitute  one  great 
rregular  excavation,  viz  :  Maple  Grove  pits ;  P.  Kline's 
nines  ;  J.  Barber  &  Co.'s  ;  Hensinger  mines  leased  by  the 
A.llentown  I.  Co.;  Thomas  I.  Co.'s;  Hensinger  &  Saul's; 
Mickley's  ;  Hensinger  Heirs';  Keifer's  ;  Desh's.* 

This  southern  range  is  continued  eastward  across  North- 
ampton county  along  the  north  foot  of  the  Lehigh  mount- 
ain as  far  as  the  Delaware  river  opposite  Easton,  as  already 
described. 

The  second  range  lies  in  the  limestone  country  to  the 
north  of  the  first  range,  and  embraces  the  mines  of  Ludwig 
(2)  ;  Butz  ;  Yager ;  H.  Kaiser ;  Blank  ;  Smoyer  (4) ;  B. 

*Many  of  these  mines  were  stopped  in  1874  on  account  of  the  depression 
in  the  iron  trade.  Some  had  been  abandoned  ;  some  had  their  machinery 
standing,  ready  to  be  exploited  again.  They  are  all  located  by  numbers  on 
the  sheets  of  the  Lehigh  survey  map,  executed  by  Mr.  Clark  under  Pro- 
fessor Prime's  direction,  and  published  with  Report  D,  1875.  Their  descrip- 
tions appear  on  pages  17  to  24  of  that  report. 


234  GEOLOGICAL   SURVEY    OF   PENNSYLVANIA. 

Smoyer ;  J.  Smoyer ;  B.  P.  Smoyer ;  Judith  Smoyer ;  T. 
Smoyer  ;  A.  Smoyer  ;  Reub.  Romig  (2) ;  P.  Romig  ;  Werner 
&  Reinhart ;  and  Lauer. 

The  third  range,  further  north,  comprises  the  mines  of 
Weiler  ;  Crane  &  Thomas  I.  Co.  ;  Lichtenwallner  ;  Smoyer  ; 
Geruart ;  Sholl ;  J.  Bastian  ;  E.  Bastian  ;  and  F.  Guth. 

The  fourth  range,  further  north,  comprises  the  mines  of 
F.  Breinig  ;  Moser  ;  T.  Breinig  ;  Whitely  ;  Fogel ;  Schwartz  ; 
Bortz  ;  Koch  ;  Grammis  ;  Gackenbach  ;  Fischer  ;  J.  &  D. 
Smith  ;  Haines  ;  Miller ;  Scholl  &  Co.;  Steininger  ;  Moyer  ; 
Stein  ;  J.  Laros  ;  Levi  Lichtenwallner  ;  Krcemlich  and  Lich- 
tenwallner ;  and  the  trial  pits  at  Chapman's  station  ;  and 
the  mines  in  the  Fogelsville  Cove,  although  these  lie  really 
further  north  next  the  slate  region. 

Ninety-eight  (98)  mines,  mostly  open  quarries,  large  and 
small,  shallow  and  deep,  are  named,  enumerated  and  located 
on  the  first  map  of  Lehigh  county,  published  with  Prof. 
Prime's  first  report  of  topographical  work  done  in  1874  (D, 
1875). 

One  hundred  and  three  (103)  others  were  in  1875,  1876, 
named,  enumerated  and  located  on  the  four-sheet  colored 
map  of  the  county  published  with  Report  D2  in  1878. 
These  are  classified  geographically  thus  : 

In  the  first  range,  along  the  foot  of  the  South  mountain: 
— Reder  ;  Desh  ;  Shelly  ;  Daney  ;  Schwartz  (Dan.);  Emaus 
I.  Co.;  Bader;  Trexler  &  Kline;  Kline  (H.)  three;  Kline 
(Jessie);  Kemmerer ;  Keck  &  Ritter ;  Kline  (G.);  Stein; 
Hottenstein ;  Apple;  Kipping  &  Holsbach;  Seam;  Whit- 
man ;  Spinner. 

North  of  the  Little  Lehigh : — Reinhart  ;  Jobst ;  Wenner; 
Kemry  &  Carbon  I.  Co. ;  Smoyer ;  Steiner  &  Kehm ; 
Woodring  ;  Roth  ;  Glick  (L.  and  C.)  two;  Acker  ;  Reinhart. 

In  the  middle  of  the  limestone  country: — Schadt;  Rush  ; 
Ritter  ;  Sheirer  ;  Mclntire  ;  Miller  ;  Biery  ;.Wennor ;  Roth  ; 
Butz  &  Belden  ;  Singmaster  ;  Butz  ;  Walbert ;  Descher. 

Northern  edge  of  limestone  : — Barber  &  Aimy  ;  Marck  ; 
Scherer  ;  Jobst ;  Kratzer  ;  Crane  I.  Co. ;  Wenner  ;  Guth 
(D.  A.);  Thomas  I.  Co.;  Weaver;  Klein;  Sieger;  Crane 
I.  Co.;  Gackenbach  ;  Blank  ;  Guth(C.);  Guth  (H.);  Henry  ; 
Boyer  ;  Balliet ;  Levan  ;  Henninger ;  Schadt ;  Baer. 


BERKS   COUNTY   LIMONITE   MINES.  235 

Mines  at  Ironton: — Kennel  (Ironton  RR.  Co.);  Mickley; 
Ironton  Co.;  Balliet  Bros.;  Balliet  heirs;  Brown;  Bitter; 
Steckle  (P.);  Steckle  (D.);  the  last  two  east  of  Ironton.* 

Berks  county  limonite  mines. 

The  Lehigh  ore  belts  are  continued  westward  towards  the 
Schuylkill ;  but  most  of  mines  named,  enumerated  and  lo- 
cated on  the  map  of  Mr.  d'Invilliers'  Report  D3,  Vol.  2, 
1883,  chapter  10,  are  next  to  or  not  far  from  the  Lehigh 
county  line.  The  limestone  valley  (between  the  South 
mountains  and  Hudson  River  slate  edge  hill)  is  narrowed 
down  in  Berks  county  to  about  2  miles,  then  widens  to  about 
4  miles  and  so  continues  to  the  Schuylkill.  The  narrow- 
ness of  it  just  at  the  Berks-Lehigh  line  is  brought  about 
by  a  jog  in  the  South  Mountains  and  two  extensions  of  the 
slate  hills  southward  toward  the  jog  ;  the  slates,  of  course, 
overlying  the  limestone.  It  is  remarkable  that  just  here 
have  been  made  nearly  40  excavations,  and  that  scarcely 
any  ore  has  been  found,  or  at  least  mined,  in  the  limestones 
for  the  15  miles  west  to  the  Schuylkill ;  the  two  Moselem 
banks  being  the  solitary  noted  exceptions,  and  these  lie  at 
the  edge  of  the  slate.  These  facts  make  it  likely  and  in  fact 
almost  certain  that  the  ore  deposits  on  the  limestone  surface 
near  the  county  line  owe  their  origin  to  the  damourite  slates 
at  the  top  of  the  limestone  series,  which  once  bridged  the 

*  The  great  Ironton,  or  old  Balliet  mine,  is  one  of  the  geological  wonders 
of  the  State,  an  excavation  2000'  long,  800'  broad  and  90'  deep,  worked  for 
more  than  half  a  century.  But  as  the  damourite  slates  of  this  mine  are  of  an 
entirely  different,  higher  horizon  and  later  age,  namely  at  the  top  of  the 
limestone  series,  it  does  not  properly  come  into  this  chapter  on  the  lower 
damourite  slate  belt  {primal)  of  limonite  ores  at  the  bottom  of  the  series. 
I  have  found  it  impossible  to  avoid  reference  in  this  chapter  to  all  the  limo- 
nite mines  of  the  valley,  because  of  the  difficulty  of  selecting  out  those 
which  are  exclusively  confined  to  the  lower  outcrop  of  slate.  Some  of  those 
in  the  very  center  of  the  valley  may  be  in  the  lower,  or  in  the  upper  slates, 
or  in  slates  of  some  intermediate  horizon.  The  valley  limestones  are  ex- 
cessively compressed  and  crimpled ;  so  that  on  lines  of  anticlinal  the  lower 
slates  may  appear  at  the  present  surface  (although  that  is  not  at  all  probable 
except  in  rare  cases);  while  on  lines  of  synclinal  the  upper  slates  may  be 
and  probably  sometimes  are  preserved  at  the  present  surface.  I  was  also 
anxious  to  give  in  this  chapter  a  general  view  of  the  iron  ore  wealth  of  the 
region.  The  description  of  the  Ironton  mines  is  therefore  postponed  to  a 
following  chapter. 


236  GEOLOGICAL   SURVEY    OF   PENNSYLVANIA. 

valley,  and  still  bridges  it  half  way.  And,  if  this  be  so, 
then  it  is  possible  that  all  the  200  and  more  mines  in  the 
limestone  belt  of  the  three  counties  must  be  referred  to  the 
top  damourite  slates,  and  not  to  the  Primal^  the  bottom. 
It  is  an  additional  testimony  to  this,  that  the  two  greatest 
limonite  mines  of  the  region,  the  Ironton  in  Lehigh  and 
the  Moselem  in  Berks,  are  in  the  upper  damourite  between 
the  limestone  belt  and  the  slatebelt.* 

The  lower  damourite  (Primal  Upper  hydro-potash-mica 
slate)  lying  upon  the  Chiques  quartzite,  follows  the  north- 
ern foot  slope  of  the  South  Mountains  around  to  Reading. 

A  group  of  ten  limonite  banks  are  located  in  the  cove 
at  the  head  of  the  Little  Lehigh.  south  and  west  of  Sham- 
rock (S.  E.  of  Topton).  A  mine  is  just  south  of  Topton  ; 
another,  1  mile  S.  E.  of  Bower's  station  ;  two  more  a  mile 
S.  W.  of  Lyons  station  ;  five  more  S.  of  Fleetwood  station  ; 
another  (Shaefer's)  i  m.  S.  E.  of  Blandon  station. 

In  Oley  Valley. 

In  the  Oley  Valley,  Hunter's  &  Weaver's  mines  are  2  m. 
S.  W.  of  Friedensburg  ;  and  these  are  the  only  limonite  banks 
in  the  body  of  the  highlands  in  Berks  county  except  the 
Bittenbender  and  Gehman  banks  5  m.  S.  of  Alburtis. 

But. there  are  indications  of  a  siliceous  hematite  connected 
with  the  Chiques  quartzite  beds  in  many  other  places.  The 
ores  of  this  formation  where  exploited  have  been  found  not 
only  silicious,  but  so  phosphatic  and  with  so  little  alumina, 
magnesia  and  lime  as  to  make  cold  short  iron  invariably. 
These  ores  however  seem  in  all  cases  to  be  the  product  of 
the  overylying  damourite  slates,  the  iron  of  which  set  free 
has  found  a  home  in  the  quartzite,  especially  where  this  is 
in  a  sandstone  condition. f 

The  Udreeore  ~ba,rik  in  Ruscom  Manor  on  the  N.  flank  of 
Furnace  Hill,  1£  m.  S.  W.  of  Pricetown,  was  the  largest 
producing  bank  in  the  mountains  in  1882  ;  belonging  to 

*In  a  following  chapter  this  famous  Ironton  mine  will  be  described  in  de- 
tail (from  D2,  p.  39,  &c.,  as  examined  and  mapped  by  the  survey  in  1875;, 
because  it  is  the  best  and  most  typical  deposit  of  limonite  in  this  region  of 
the  state,  and  the  most  instructive  for  the  elucidation  of  the  structural  rela- 
tionship between  the  limestone  and  slate  formations  of  the  Great  Valley. 

t  See  D3,  p.  361. 


OLEY   VALLEY   LIMONITES.  237 

the  Clymer  I.  Co.,  and  located  in  the  sandstone  close  to 
the  gneiss  ;  worked  since  1871  by  the  Clymer  I.  Co.  for  Mt. 
Laurel  Furnace ;  mostly  wash  ore  ;  some  bombs ;  hand- 
some specimens  of  concretions  and  stalactites  ;  varieties  of 
gothite,  lepidocrocite.  turgite,  red  and  yellow  ochre  ;  too 
cold  short  for  the  neighboring  Oley  furnace  ;  cheaply  mined 
as  an  open  cut,  70'  deep ;  ore  dipping  70°,  N.  20°  E.,  20' 
thick  ;  300'  along  outcrop  ;  horses  of  clay  ;  18  to  20  tons 
per  day  ;  analysis  by  McCreath  : — Iron  40.05  ;  manganese 
3.314;  sulp.  .003;  phos.  .522;  sil.  matter,  22.44. 

The  Warner  mine,  \\  m.  S.  E.  of  Friedensburg.  at  the 
junction  of  Oley  slates  and  limestone,  the  line  of  contact 
crossing  the  open  cut ;  Clymer  I.  Co.  for  Oley  furnace ; 
damourite  slate  (turned  to  white  and  buff  clay),  largely  used 
for  excellent  building  brick  ;  wrought  for  18  years  ;  10  to 
15  tons  per  day  ;  ore  dips  30°  to  50°  N.  W.  (away  from 
slate  hill),  as  a  bed  2'  to  8'  thick  underlaid  with  clay  ;  shaft 
sunk  (1878)  49'  to  2'  hard  ore  bed  ;  at  56'  another  8  foot  ore 
bed  (50  per  cent,  lump);  clay  between  the  two  beds,  but 
second  bed  nearly  flat,  etc.  See  interesting  description  of 
efforts  to  get  water  at  this  dry  mine  on  page  365.* 

The  Hunter  mine,  300  yards  N.  W.  of  the  last  (Weaver), 
was  abandoned  when  visited  in  1882,  and  is  accounted 
almost  if  not  quite  exhausted,  being  wholly  in  the  lime- 
stone One  shaft  was  sunk  90'  through  yellow  clay,  to  a 
1'  bed  of  white  kaolin,  under  which  lay  V  or  2'  of  limo- 
nite  ore  ;  under  this  a. little  black  clay  holding  concretions 
of  carbonate  of  iron  (siderite);  under  this  a  thin  bed  of 
mixed  black,  clay  and  limonite.t 

*  Carbonate  of  iron  (siderite)  has  been  seen  here,  but  apparently  in  no 
great  quantity.  It  is  important  for  the  genesis  of  limonite. 

f  This  shaft  section  is  extremely  interesting,  as  there  can  be  no  doubt  that 
the  black  clay  must  have  held  pyrites  and  siderite,  and  by  the  decompo- 
sition of  these  the  limonite  was  produced,  precisely  as  in  the  case  of  the 
Devonian  Marcellus  ore  mines  of  Mifflin  county  on  the  Juniata  river,  which 
will  be  described  in  a  future  chapter. 

The  kaolin  in  this  mine  has  been  a  good  deal  mined.  The  best  quality, 
No.  1  white,  used  to  be  sold  at  from  $7  to  $15  a  ton  to  Connard's  paper  mill 
at  Pleasantville,and  Burgess's  paper  mill  at  Spring  City.  Opposite  Royer's 
Ford,  No.  1  was  a  deposit  30'  by  20'  under  6'  of  cover,  pinching  out  all 
round.  Of  the  three  grades  there  were  about  800  tons.  (See  four  compara- 
tive analyses  by  McCreath,  D3,  p.  368.) 


238  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

The  Manwiller  mine,  1£  m.  W.  N.  W.  of  Griesermers- 
ville,  Oley  township,  entirely  in  the  limestone,  was  started 
in  1873  and  abandoned  in  1878  ;  there  was  a  fair  showing  of 
lump,  but  the  whole  was  merely  a  pocket  like  so  many  of 
the  smaller  limonite  banks  of  the  region.  About  2000  tons 
were  got. — Ore  can  be  seen  cropping  out  in  the  little  Dale 
Forge  limestone  valley  in  Washington  township. — 5000  tons 
were  taken  from  the  J.  Rush  bank  in  Hereford  township, 
now  filled  with  water. — 5000  tons  were  got  from  one  of  the 
Bittenbender  banks  (in  the  same  township)  during  5  years 
work  ;  greatest  depth  of  open  cut  50'.  in  limestone  and  clay ; 
great  quantity  of  flint  mixed  with  the  bottom  ore. — 1000 
tons  were  mined  from  the  adjacent  Gerham  bank,  but  con- 
demned for  its  excess  of  silica.* 

Schweitzer  &  Kurtz  bank,  \\  m.  N.  E.  of  Pricetown,  and 
Schaeffer'  s  at  Fleetwood,  were  new  mines  in  (1882),  in 
limonite  which  belonged  to  the  quartzite  beds.  (D3,  p.  371.) 

The  Muhlenberg  (Beidler]  bank,  W.  of  Reading,  in  lime- 
stone, an  open  cut  30'  deep,  shows  much  siliceous  limonite, 
with  slate  and  clay  holding  the  ore. — Seitzinger  bank,  a 
mile  nearer  Reading,  has  limestone  outcrops  east  and  west 
of  it.— The  Eureka  bank,  3£  m.  W.  of  Reading,  a  40'  cut, 
yielded  cleaner  cellular  ore,  with  little  or  no  pyrites,  but 
some  oxide  of  manganese. 

Cumberland  County  limonite  mines. 

The  limonite  mines  of  Cumberland  and  Franklin,  along 
the  foot  of  the  South  mountains,  as  far  as  Mont  Alto,  are 
described  in  a  special  report  of  the  Iron  Ores  and  Limestone 
Quarries  of  the  Cumberland  Valley  by  Mr.  E.  V.  d'lnvil- 
liers.  f 

Beginning  at  the  east  end  of  the  South  mountains,  12 

*These  banks  run  parallel  to  and  800'  S.  of  the  magnetic,  ore  workings  higher 
up  the  hill  in  the  gneiss,  and  have  nothing  to  do  with  that  ore.  The  mag- 
netite mines  of  Berks  will  be  described  elsewhere. 

f  Annual  Report  of  the  Geological  Survey  for  1886,  part  IV  with  two  maps. 
They  were  also  described  by  me  in  a  private  report,  with  illustrations, 
published  in  the  proceedings  of  the  American.  Philosophical  Society  of 
Philadelphia,  Jan.  3,  1873. — Mr.  McCreath's  analyses  will  be  found  in  Report 
M3,  1881. 


CUMBERLAND    COUNTY   LIMONITE   MINES.  239 

miles  west  of  Harrisburg,  we  have  (going  west)  the  follow- 
ing limonite  mines  :* 

Leidig  &  Hoffer  (30);  Beltzhoover  (29);  Ege  (28);  Pepper 
(27);  Strickler  (26);  King  (8);  Pepper  (7);  Grove,  or  Peach 
Orchard  (6);  Big  Pond  (4);  G.  H.  Clever  (5);  Clever  Mam- 
moth (3);  Muslin  (39);  Chestnut  (38);  J.  H.  Cressler  (37); 
J.  Bridges  (36);  all  in  Cumberland  county  and  south  of  the 
Yellowbreeches  creek  and  Harrisburg  and  Potomac  rail- 
road.—Then  in  Franklin  county  Ahl  (27);  McHose  (28) 
on  the  railroad  ;  Cressler  (29);  Koser  (30);  Southampton 
(23);  Ruby  (24);  Gochenauer  &  Rohrer  (25);  Means  (26), 
all  in  the  ravine  of  Furnace  Run. — Then  along  the  Mont 
Alto  railroad  Stephen's  Pond  (8);  McNeal  (7);  Roth  (5); 
Pond  No.  1  (9);  Pond  No.  2  (10);  and  the  group  back  (E.) 
of  the  Pond  banks,  viz:  English  (11);  Promise  (13);  Hope 
(12);  Wiesling  (15);  Limekiln  (16)  ;  White  Rock  (18); 
Calliman  (17);  Guilford  (14);  then  again  on  the  railroad. 
J.  Rock  (6);  No.  32  ;  George  (20);  No.  8 ;  No.  5  ;  l$o.  4  ; 
No.  3  ;  No.  2  ;  No.  1,  of  the  Mont  Alto  (1);  Mill  Bank 
(3?);  Smith  and  Avery  (2);  Wythe  Douglass  (22);  Pass 
Orchard  (21);  G.  Rock  (20);  and  lastly  R.  McCreary  (19); 
on  the  Baltimore  and  Cumberland  Valley  road. 

Leidig  &  Hojfer's  bank  is  a.  small  abandoned  digging  in 
the  cove  between  two  of  the  end  spurs  of  the  South  Mount- 
ain, 3£  m.  S.  E.  of  Boiling  Springs. 

Beltzhoover  'bank,  1350'  long,  180'  wide  and  80'  deep,  on 
the  north  west  side  of  the  spur  ;  open  cut  to  south  separated 
from  main  ore  by  200'  of  yellow  clay ;  ore  body  not  more 
than  40'  thick  ;  60,000  tons  won.f 

*  On  the  small  maps  in  Ann.,  1886,  part  IV,  p.  1437,  the  mines  are  num- 
bered, and  the  names  are  given  in  the  columns  at  the  bottom  of  the  maps ; 
but  on  the  larger  maps  in  the  Atlas  to  the  volume  (part  IV)  the  names 
alone  are  given.  It  is  a  pity  that  no  geographical  arrangement  of  mines 
according  to  numbers  was  possible ;  but  I  here  endeavor  to  diminish  some- 
what the  embarrassment  thus  produced  for  the  reader  by  taking  the  mines 
along  the  foot  of  mountain  in  order  first,  especially  as  these  are  certainly  in 
the  Primal  hydromica  or  lower  damourite  slates  beneath  the  limestone. 

t  Here  the  ore  dips  distinctly  40°  to  50°  N.  and  N.  E.  away  from  the  mount- 
ain. Variegated  clays  overlie  the  ore  on  the  north,  and  are  manganiferous 
Ore  rests  on  reddish  sandy  slate,  beneath  which  no  ore  is  found.  The  old 
Crockett  bank  is  further  west  up  the  hollow.  The  Siplinger  bank  is  also 
long  abandoned.  Trial  pits  sunk  westward  found  no  ore.  at  least  for  30 


240  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

Ege  bank  (Big  bank)  of  Phila.  &  Reading  I.  Co.  2  m.  S. 
of  Boiling  Springs,  an  immense  excavation,  practically 
abandoned  (in  1886)  and  the  shafts  and  faces  fallen  in  ;  1500' 
long,  250'  wide,  70'  deep  at  south  end.  At  the  west  end  the 
ore  was  drifted  on  and  found  always  dipping  steeply  S.  E. 
into  the  mountain,  thickening  and  thinning  but  "  with  an 
average  thickness  of  25  to  40  feet." 

Pockets  of  manganese-iron  ore  edge  the  main  body,  and 
weathered  into  sooty  clay  masses  or  large  spots  in  the  white 
clay  mass.  The  wash  ore  is  mostly  removed  ;  the  remain- 
ing solid  bottom  ore  is  of  poorer  quality,  and  expensive  to 
mine.  The  greatness  of  this  mine  may  be  judged  from  the 
fact  that  the  lease  called  for  50,000  tons  per  annum  ;  but  it 
never  actually  yielded  more  than  35,000  tons  in  any  one 
year. 

Pepper,  or  Old  bank,  near  the  head  of  a  little  limestone 
valley  extending  around  a  ringer  of  the  mountain  2£  m.  S. 
W.  of  Boiling  Springs  ;  trench  375'  long,  150'  wide,  45'  deep  ; 
east  end  wall,  buff  clay  and  sand,  wash  ore  ;  west  of  plane, 
white  clay  streak  12'  wide ;  balance,  good  and  poor  ore 
ground  mixed  ;  many  black  manganese  blocks  ;  abandoned 
(1883).  In  1873  I  saw  a  stope  70'  high,  showing  25'  wash  ore 
above,  45'  solid  ore  below,  arranged  in  fine  anticlinal  arch;* 
shafts  from  the  floor  down  went  through  35'  more  of  solid 
ore,  making  100'  of  ore  ground  in  all.  At  least  100,000  tons 

beneath  the  surface.  A  low  tunnel  was  driven  in  white  clay  along  the  N. 
edge  of  the  ore  body  to  keep  it  in  sight,  and  the  tunnel  doubled  on  itself  N. 
W.  showing  an  anticlinal  structure,  such  as  I  saw  in  the  heading.  See  foot 
note  to  d'Invillier's,  p.  1468.  Toward  the  east  end  the  ore  body  swelled  to 
400'  broad.  No.  3  tunnel  775'  long,  from  the  RR.  to  the  ore,  was  cut  to  avoid 
a  plane.  It  was  driven  650'  before  the  ore  was  reached,  proving  again  the 
strange  S.  E.  dip  of  the  damourite  slate  formation  here.  See  many  other 
interesting  details  in  d'Invillier's  report;  among  them  that  the  manganese 
deposits  limit  the  ore  in  this  as  in  other  banks  in  this  vicinity.  Eastward 
the  ore  shelves  up  and  covers  a  wedge  of  limestone  160'  thick.  Trial  shafts 
eastward  have  not  been  very  satisfactory ;  but  it  is  supposed  that  the  ore  is 
practically  continuous  to  the  Beltzhoover  bank,  3700'  distant.  There  is  a 
considerable  amount  of  shot  ore  largely  mixed  with  quartz.  The  trial  pits 
were  usually  in  a  greenish  talcose  slate  (soapstone)  of  the  miners. 

*See  my  pen  and  ink  sketch  of  it  in  Amer.  Phil.  Soc.  Proc.,  Jan.  3,  1873, 
page  9.  I  estimated  a  possible  9,000,000  tons  along  the  little  valley  leading 
up  to  the  Strickler  mine ;  but  it  must  have  been  an  overestimate. 


MOUNTAIN   CKEEK    LIMON1TE  BANKS.  241 

of  ore  were  taken  out  prior  to  its  abandonment ;  ore  excellent 
for  gun  metal ;  used  at  Boiling  Springs  furnace  75°  to  85° 
per  cent,  to  15°  'to  25°  per  cent,  limestone  ore,  hematite  or 
magnetic.* 

Strickler  bank,  on  the  high  divide  back  of  the  finger 
mountain  and  at  the  head  of  the  vale  of  the  Old  mine  (f  m. 
W.  S.  W.  of  it).  It  is  a  mile  E.  of  Mt.  Holly  Springs 
(paper  mills).  The  bank  in  1883  was  200'  long  by  120'  wide 
and  W  deep  to  level  of  water ;  the  mine  having  been  long 
abandoned  after  yielding  possibly  40,000  tons.f 

The  ravine  descending  from  the  high  divide  at  the 
S  trickier  bank  west  down  to  the  Mt.  Holly  banks  corres- 
ponds to  the  ravine  descending  from  the  Streckler  bank 
east  to  the  Old  bank  ;  and  the  line  continued  west  past 
Mt.  Holly  banks  is  straight  up  Mountain  Creek  valley  to 
the  Pinegrove  Furnace  banks,  in  the  heart  of  the  moun- 
tains. Why  Mountain  creek  did  not  keep  on  and  issue  at 
the  Old  bank  is  an  interesting  structural  (and  erosion) 
question.  No  ore  has  been  found  in  the  test  pits  along  the 
ravine. 

Mountain  Greek  limonite  banks. 

The  first  two  banks  ascending  the  valley  are  the  Mt. 
Holly  mines,  1  m.  S.  of  Mt.  Holly  Springs,  on  the  south 
side  of  the  creek,  150  yds.  up  the  slope  at  the  foot  of  the 
mountain.  They  were  both  abandoned  when  visited  by 

*  Carlisle  Iron  Works  property  on  which  all  these  banks  stand  is  10,000 
acres.  Furnace  recently  (1883)  improved,  with  hot  blast,  <fec. — Analysis  of? 
large  sample  by  McCreath :  Iron,  45.1;  rnang.,  0.23;  sul.,  0.20;  sil.  matter 
21.02;  phos.,  0.176. 

t  The  road  over  the  divide  runs  along  the  N.  side  of  the  bank  above  it, 
and  under  a  remarkable  cliff  of  quartzite,  or  sandstone  beds,  descending 
(south)  from  the  top  of  the  mountain  at  an  angle  of  20°  or  30°,  as  if  to  go 
under  the  ore,  but  broken  off  at  the  bank,  as  if  it  once  overlaid  the  ore.  A 
curiously  interesting  exhibition  of  erosion,  with  or  without  faulting,  I  know 
not  which.  I  saw  in  1873,  20'  of  lump  and  wash  ore  then  worked,  and  a 
sump  of  26  deep  sunk  in  solid  ore  in  the  floor  of  the  bank.  About  20,000 
tons  had  been  already  removed,  and  the  rate  of  shipment  then  was  18  tons  a 
day.  McCreath's  analysis  of  his  own  samples  was :  Iron,  43 ;  mang.,  .01 
sulp.,0.3;  sil.  mat.,  19.0;  phos.,  1.4.  All  the  ores  of  this  range  contain  much 
manganese  and  phosphorus. 
16 


242  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

Mr.  d'Invilliers  in  1886.  Dr.  Frazer  describes  them  in  his 
Report  C2,  1877,  thus  : 

Thomas  Iron  CoSs  banTc\  225' long;  225' wide ;  begun 
about  1872 ;  average  production  30  tons  per  day  ;  nearly 
exhausted  and  half  full  of  water  in  1876.  In  the  southeast 
heading  the  edges  of  the  slates,  converted  into  ore  bearing 
clay  layers,  dip  visibly  55°,  N".  60°  W.  Bands  of  limonite 
concretions  are  interbedded  with  pink,  white  and  yellow 
clays  much  crumpled  with  N.  W.  and  S.  E.  dips.  Red 
oxide  stains  some  of  the  clays  a  bright  red.* 

Medlar  and  Baylor's  lank*  200  feet  S.  W.  of  the  last, 
is  an  open  quarry  (about  2  acres),  600'  long  by  200'  to  300' 
wide,  and  20'  to  30'  deep  ;  begun  by  Geist  &  Krauf  t  in  1840; 
first  really  worked  by  Medlar  &  Saylor  in  1870,  on  a  4000 
ton  per  annum  lease  at  75  cents  royalty  ;  daily  average  70 
to  80  tons  in  1876.  f 

Grove  bank,  Hunter's  Run  station,  2  m.  above  Mt.  Holly, 
south  side  of  the  creek,  just  above  the  mouth  of  Hunter's 
run.  Opposite  to  it,  north  of  the  creek,  and  up  the  foot 
slope  of  the  north  mountain,  are  the  four  following  banks 
in  a  row : 

Lehman  bank,  opposite  the  Grove  bank,  idle  in  Oct., 
1886  for  want  of  water  ;  a  bore  hole  went  down  through  ore 
for  31)0' ;  then  through  blue  clay,  40' ;  then  white  clay,  30' ; 
then  "mountain  clay,"  25'  to  "Potsdam  sandstone"  (Mt. 
Holly  c[uartzite)=435'4  In  1887  mining  recommenced ; 
pit  then  250'  long,  50'  wide  ;  ore  excellent;  £  ore  in  places  ; 
but  average  of  mine  ore  to  clay  only  1:8  or  1:10  ;  no  solid 
ore  ;  dip  very  irregular. 

*No.  159  on  the  map  of  York  and  Adams  Co.  in  C2.  Medlar  bank,  on  map 
to  An.  Rt  1886,  iiii,  p.  1463. 

fit  Is  said  1000  tons  a  month  was  mined  out ;  and  that  much  good  ore  re- 
mains ;  but  the  ore  of  both  these  pits  is  rankly  cold  short,  and  mining  costly. 
At  least  100,000  tons  have  been  taken  from  the  two  pits  to  mix  with  Cornwall 
ore  in  the  Harrisburg  furnaces.  Analysis  of  McCreath's  sample  of  mixed 
lump  and  ball :  Iron,  38.25 ;  mang.,  2.73  ;  sulp.,  0.005  ;  sil.  mat.,  23.55  ;  ptios., 
1.37.— Of  dark  brown  cellular  lump  :  48.50;  0.73;  0.006;  11.27;  1.62.  (d'Invil- 
liers, 1886.)— See  statistics  of  wages  and  machinery  in  1874,  in  C2,  p.  240. 

JThese  figures  must  be  very  misleading  considering  the  steep  dip  of  the 
quartzites  at  Mt.  Holly,  and  consequently  of  the  slates,  which  have  decom- 
posed into  ore  bearing  and  other  clays. 


MOUNTAIN   CREEK   LIMONITE   BANKS.  243 

Crane  Iron  Co.  banks,  £  in.  W.  of  last ;  open  cut  250' 
long,  50'  wide  ;  tunnel  driven  in  at  lower  level  from  washer; 
bottom  of  cut  being  sloped  down  to  tunnel ;  stripping  20'  at 
the  least,  and  up  the  mountain  (over  the  best  ore)  ' 'enor- 
mous," mostly  of  sandy  blue  and  white  clay  ;  output,  1886, 
30  tons  a  day  for  Columbia,  Pine  Grove,  Dunbar  and  New- 
port furnaces  ;  afterwards  increased.  East  of  pit  a  shaft 
went  through  50'  ore  ;  cross  cut  through  50'  ore  and  clay.* 

Dunbar  (R.  Boyer]  mine,  i  m.  W.  of  the  Crane ;  new  in 
1887  ;  shaft  60'  deep  ;  main  gangway  (northward)  through 
140'  ore  clays,  then  80'  through  barren  clays  ;  drift  west- 
ward 150'  in  ore  clay,  lean,  1:10  ;  two  drifts  (eastward)  meet- 
ing irregular  and  thin  deposits  of  ore.f 

Chestnut  Hill  bank,  adjoining  the  last  at  the  west  end  of 
the  row,  \  m.  N.  of  the  railroad  and  1£  m.  W.  of  Hunter's 
Run  station ;  ore  crops  abundant ;  tunnel  to  take  the  ore 
beneath  heavy  stripping  commenced  in  the  autumn  of  1886  ; 
ore  body  tested  to  depths  of  30'  to  40',  E.  and  W.  of  tunnel; 
large  pump  on  the  creek  for  water  supply  ;  tunnel  mouth 
110'  above  RR.  grade  ;  strikes  ore  clay  at  130'  in  and  keeps 
230'  further  in  ;  ore  ground  rich  and  lean  alternately;  most 
of  the  lump  ore  next  the  mountain  ;  wash  ore  on  varigated 
clays  in  front  of  it  towards  the  valley  ;  average  ore  to  clay, 
1:10  ;  ore  rich  (47  to  49  per  cent.)  low  in  phosphorus  (.08 
to  1.0);  3000'  of  outcrop  tested  by  trial  pits  and  shafts  ; 
ore  for  Chestnut  Hill  furnaces. 

Koontz  &  Meyers  bank,  opposite  last  on  south  side  of 
creek;  small ;  abandoned  for  years. 

Diverts  bank,  just  west  of  last ;  small ;  abandoned. 

Henry  Clay  bank,  west  of  last ;  150'x60';  full  of  water 
in  18864 

*The  stratification  of  ore  and  clay  in  bands  and  irregular  masses  is  very 
marked  in  this  bank ;  but  so  wavy  as  to  prevent  any  theory  of  general  dip 
structure.  There  has  been  a  vast  deal  of  settling  and  sliding  and  com- 
pression during  the  process  of  slate  mouldering  and  ore  concentration. 

fThe  main  tunnel  seems  to  have  gone  through  three  distinct  ore  beds,  2' 
to  3'  thick  each,  separated  by  barren  clays,  in  the  first  140',  as  described  in 
the  text;  all  the  ores  and  clays  standing  vertical,  i.  e.  varying  between  70°, 
N.  and  70°  S.  In  strong  contrast  to  this  the  ore  overhead  at  the  end  of  the 
west  entry  dipped  very  gently  south. 

t  In  all  these  banks  the  best  ore  is  now  (1886)  entirely  covered  up,  the 
openings  having  been  abandoned  when  the  lump  ore  was  met  with.  They 


244  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

Seyfert  &  McManus  'bank  ;  150'  W.  of  last ;  abandoned, 
but  not  exhausted. 

Lanigan  lank,  300'  W.  of  last ;  120'x90',  30'  deep  to 
water ;  sides  covered  with  wash  of  sand  and  stone  and 
yellow  clay  ;  15,000  tons  mined  out,  and  good  show  of 
lump  ore  in  floor  when  abandoned. 

Laurel  No,  <2  bank,  nearly  3  m.  W.  of  last ;  200'xlOO'; 
vigorously  worked  from  1878  to  1881  ;  neutral  liver  colored 
limonite  in  yellow  clays.* 

Laurel  No.  1  bank,  £  m.  W.  of  last,  close  by  Pine  Grove 
Furnace  RR.  station  (2£  rn.  N.  E.  down  stream  from  Pine 
Grove);  on  N.  slope  of  terrace;  small  cellular  lump,  easily 
picked,  and  hard  lump  bottom  ore,  blasted  ;  chief  depen- 
dance  of  the  furnace,  mixed  with  Lehman  bank  ore  ;  out- 
put running  nearly  up  to  150  tons  per  day  ;  heavy  ore  to 
clay  1:1;  wash  ore  much  less;  dip  S.  E.,  wavy,  sometimes 
N.  W.;  tunnel  from  W.  end  N.  W.  towards  RR.  through 
50'  "  top  clay"  into  higher  ball  ore  clay.  Another  tunnel 
S.  E.  230',  mostly  in  ore  ground,  with  blue  clay  intervals, 
rising  S.  E.  but  wavy,  most  of  the  ore  to  the  west  of  it ; 
ore  very  dense  with  much  flint,  f 

Pine  Grove  No.  1  bank ;  1£  m.  W.  of  last,  and  i  m.  E. 
of  the  furnace  (opposite  the  limestone  quarry  onvthe  north 

all  occur  on  the  flat  plateau  gently  rising  southwards  up  the  flank  of  the 
main  mountain,  and  are  largely  accompanied  by  quartzite  and  sandstone  ; 
no  limestone  showing  anywhere."  D'lnvilliers.  Analysis  :  Iron,  35.85  (lump 
ore,  50.25);  Mang.,  2.25  (0.07);  Sulp.,  0.03  (0.007)  ;Sil.  mat.,  31.89(10.65);  Phos., 
0.18  (0.51);  McCreath. 

*  The  mountain  spur,  coming  from  the  west,  south  of  Pine  Grove  furnace, 
on  which  this  opening  was  made,  ends  here,  and  the  mine  is  well  round  its 
N.  E.  end,  on  nearly  flat  dips,  probably  a  dying  anticlinal.  Top  wash  ore 
12'  to  20';  clay  4';  lump  ore  masses  in  bottom  of  bank  very  compact.  (Re- 
port 1887,  p.  1453.) 

t  May  16,  1887,  of  76  car  loads  got  46  of  clean  ore,  but  this  was  from  the 
bottom  of  cut.  Output  in  May,  50  to  60  tons  per  day.  Water  tunnel  300' 
entirely  through  wash  ore  N.  under  RR.  to  creek.  But  this  indicates  syn- 
clinal with  flat  S.  dips  on  the  northern  (creek)  side  and  very  steep  over- 
turned dips  on  the  southern  (mountain)  side.  Analysis  of  lump  ore:  Iron, 
42;  Mang.,  3.5;  Phos.,  0.15.  Pine  Grove  furnace  depends  largely  on  this 
mixed  \  and  |  with  softer  non-man ganesian  limonites  from  Hunter's  run  to 
make  its  neutral  pig.  An  average  mix  of  «  Laurel  -f  i  Crane  (or  Lehman) 
gave  carwheel  pig  (\  in.  chill)  analysing:  Silica,  1.426;  Phos.,  0.305;  Sul., 
0.009;  mang.,  2.722.  McCreath. 


MOUNTAIN   CREEK   LIMONITE   BANKS.  245 

side  of  the  creek);  not  in  work  in  1886  ;  lOOO'xSOO',  and  60' 
deep  ;  output  from  1879  to  1885,  75,000  tons  ;  prior  to  1879 
(in  company  with  other  pits)  perhaps  150,000  tons  (5f  wash 
ore  ;  originally  10'  clay  and  sand  stripping,  then  25'  wash 
ore  clays,  then  25'  solid  soft  lump  ;  at  W.  end  60'  stope  ; 
drift  S.  W.  from  here  200'  and  cross  cut  150'  to  left,  all  in 
ore  ground  (largely  neutral  ore  from  surface  to  bottom  solid 
lump)  probably  continuous '  ore  ground  to  Old  bank '; 
southern  face  fine  show  of  lump  ore  ;  another  drift  from  E. 
end  200',  largely  brown  cellular  ore,  with  a  large  dome 
horse  of  white  clay.*  Northern  face  poorer  ore,  and  much 
black  clay.\ 

Old  bank,  just  W.  of  last ;  large  excavation,  long 
abandoned.  All  dips  of  ore  and  limestone  seen  in  these 
banks  are  S.  E.  No  N.  W.  dips  observed  ;  perhaps  S.  E. 
dips  are  overturns. 

Red  bank  of  the  Thomas  Iron  Co.  (abandoned)  lies  nearly 
a  mile  south  of  the  furnace  ;  opened  in  1874 ;  general  dip 
S.  E. ;  area  a  fifth  of  an  acre  ;  25'  to  30'  deep  ;  ball  ore  in 
clay,  and  a  good  deal  of  red  hematite  ;  yellow  and  white 
clay  beddings  in  natural  position  in  the  walls  apparently 
dip  N.  W.  but  may  have  crept  over  from  a  S.  E.  dtp4 

Two  large  quarries  of  limestone  lie  1000'  S.  E.  of  the 
village  of  Pine  Grove,  area  of  both  8  acres,  dips  30°,  40° 
and  45°,  S  30°  E.  Limonite  ore  has  been  taken  from  one 
of  these  limestone  quarries,  a  single  block  of  ore  weighing 
30  tons.  The  limestone  is  whitish,  bluish,  yellowish,  very 
pure  and  good  flux.§ 

Wild  cat  pits  of  the  S.  M.  M.  and  RR.  Co.,  2£  m.  S.  W. 
of  the  furnace,  shows  that  the  limonite  deposits  continue 
up  the  valley  towards  Adams  county  ;  for,  a  large  number 

*  Another  dolomitic  limestone  crops  out  S.  of  this  clay  mass  ;  dips  obscure. 

fThe  lump  ore  mining  has  been  suspended  because  it  averaged  2.25 
mang.  and  0.225  phos.  and  yet  gave  40  to  42  iron.  Analysis  of  McCreath's 
samples:  Iron,  42.15;  sulp.,  0.028;  sil.  mat.,  20.9;  phos.,  0.275. 

%  Dr.  Frazer  remarks  on  the  not  unfrequent  occurrence  of  this  tendency 
of  the  inward  dipping  clay  walls  of  limonite  mines  to  settle  and  reverse  the 
dip.  To  an  observer  facing  the  stope  the  bedding  appears  leaning  towards 
him  ;  but  the  removal  of  a  few  feet  of  wall  will  suffice  to  show  them  dipping 
away,  (CO  bottom  of  p.  246). 

§  Limestone  also  reported  seen  half  a  mile  up  the  mountain  side. 


246  GEOLOGICAL   SUEVEY    OF   PENNSYLVANIA. 

of  these  trial  shafts  30'  to  40'  deep  passed  through  ore 
ground;  but  the  50  per  cent  ore  held  an  excessive  (1.3) 
percentage  of  phosphorus,  which  deterred  the  company 
from  mining. 

Of  course  the  valley  must  be  a  synclinal  of  Chiques  sand- 
stone (the  debris  from  which  largely  covers"  the  surface), 
supporting  the  Primal  Upper  (hydromica)  slate  formation 
(furnishing  the  ore  ground)  and  that  supporting  the  lower 
beds  of  the  Great  Magnesian  limestone  (formation  No.  Ila), 
remnants  of  which  have  been  left  by  erosion,  as  shown  by 
the  quarries  opened  for  flux  for  the  Pine  Grove  furnace. 

We  return  now  to  the  north  foot  of  the  mountains,  to 
the  banks  along  Yellow  Breeches  creek. 

Limonites  along  Yellow  Breeches  creek. 

Mullen  (King)  ~bank ;  2  pits  in  front  of  Mount  Holly 
gap,  1  m.  W.  of  Papertown,  600'  S.  of  road  up  the  flank  of 
the  mountain  ;  full  of  mountain  wash ;  ore  largely  mixed 
with  chert  and  cobbles  of  sandstone  ;  white  clay  20'  wide 
crosses  the  mine  ;  long  abandoned  ;  ore  reported  good,  but 
hard  to  wash  ;  borehole  record  :  Surface  clay,  8';  ore  clays, 
128';  on  limestone.*  Shipments  of  uniformly  good  ore  to 
Steelton,  Newport,  etc.  A  good  deal  of  lump  ore.  Ore 
largely  confined  to  the  ravine  and  not  extending  far  east 
and  west. 

Peffer  old  bank,  2  m.  W.  of  Papertown,  £  m.  S.  of 
Barnitz  RR.  station,  1000'  S.  of  RR.  towards  the  mountain, 
close  to  the  junction  of  limestone  and  sandstone  ;  good  ore; 
abandoned  for  many  years  ;  say  5000  tons  won  ;  surface 
all  around  pit  strewn  with  ore  over  5  or  6  acres. 

From  this  southwest  for  seven  miles  there  are  no  mines. 

Then  the  isolated  Grove,  or  Peach  Orchard  bank,  2%  m. 
E.  of  Jacksonville,  close  to  the  mountain,  1  m.  S.  of  the 
creek  on  small  run  ;  long  ago  abandoned  ;  but  Augusta  and 
Cumberland  furnaces  ran  many  years  mainly  on  this  ore, 
using,  say,  50,000  tons. 

*  This  is  very  interesting.  The  limestone  so  high  up  the  mountain  face 
•with  ore  slate  clays  over  it  can  only  be  explained  by  either  (1)  a  universal 
overthrust  and  overturn  ;  or  (2)  a  fault,  of  which  there  is  no  evidence  ex- 
o.ept  in  the  valley  of  the  creek ;  or  (3)  a  descent  of  the  limestone  southwards 
under  the  quartzite  mountain,  which  is  inadmissible. 


BANKS   ALONG   YELLOW   BREECHES    CREEK.  247 

Big  Pond  banks,  3  m.  S.  W.  of  the  last,  2|  m.  S.  S.  E. 
of  Jacksonville,  on  the  last  head  brook  of  Yellow  Breeches 
creek  issuing  from  the  South  mountain;  in  the  slates  be- 
neath the  limestone;  abandoned  long  since,  although  fur: 
nishing  small  shot  and  some  bomb-shell  neutral  ore.* 

Clever  bank,  2  m.  S.  W.  of  Big  Pond;  100'xlOO'x40' 
deep;  stripping  10';  white,  yellow  and  red  ore  clays  in 
lower  part  of  limestone  formation. 

Cleoer  Mammotli  No.  1  bank,  1£  m.  S.  of  last,  on  first 
head  brook  of  Conococheague  creek  issuing  from  the  mount- 
ain ;  once  important ;  abandoned  long  before  1886  ;  200'x 
60'x  30'  deep  to  standing  water ;  solid  mass  of  ore  reputed 
to  be  in  the  floor  still ;  ore  costly  and  of  uncertain  quality. f 

The  Chestnut  bank  and  the  Muslin  bank  lie  between  the 
G.  H.  Clever  bank  and  the  railroad. 

The  Coffee  bank  and  the  Peacock  bank  hold  the  same  re- 
lative position  to  the  Clever  Mammoth ;  about  £  m.  E.  of 
Cleversburg  ;  in  the  Primal  Upper  slates  (damourite).  The 
Coffee  was  abandoned  Oct.,  1886 ;  stope  40',  exposed  to 
mountain  side  wash  ;  ore  in  tough  yellow  clay,  wavy,  not 
rich.  The  Peacock  was  full  of  water.  Stripping  heavy,  ore 
phosphorus  (.535). 

The  Greasier  mine,  1  m.  S.  W.,  and  the  Bridges  mine,  1£ 
m.  W.  of  Cleversburg,  are  in  the  limestone  country  south- 
east of  the  railroad. 

*  This  stream  sinks  in  the  limestone.  In  1872  I  sketched  this  range  of 
pits  (see  Fig.  13,  Amer.  Phil.  Soc.  Proc.,  Jan.  3,  1873).  Ore  at  creek  level 
down  stream,  and  75  feet  above  stream  to  the  south ;  only  one  bank  then 
active  ;  surface  clay,  22';  wash  and  lump  ore  20';  clay  in  bottom.  Elsewhere 
stripping  6'  on  solid  ore.  In  uppermost  (south)  bank  limestone  crops  out 
at  surface  dipping  8°,  S.  20°  E.,  i.  e.,  into  the  mountain;  S.  of  which  a  shaft 
went  down  through  52'  of  ore  and  clays  and  struck  limestone  at  bottom. 
This  limestone  is  very  ferruginous  and  makes  excellent  flux.  Ore  admira- 
ble, neutral,  always  worked  alone  in  the  Big  Pond  furnace,  £  m.  S.  E.  of 
bank.  Output  between  75,000  and  90,000  tons  between  1836and  1868,  making 
800  tons  of  pig  per  annum  (but  d'Invilliers  estimates  it  between  100,000  and 
150,000  tons).  Analysis:  Iron, 44;  sulphur., .03  ;  sil.  mat., 20.5;  phos.,  0.318. 

t  As  I  sketched  it  in  1872  it  showed  8'  surface  stuff;  12'  wash  ore ;  6!  ore 
with  someday  ;  9*  solid  lump  ore  and  still  in  floor;  but  clay  bottom  at  W 
end  ;  40  tons  output  per  day,  very  cold-short;  output  20,000  tons. 


248  GEOLOGICAL   SURVEY   OF  PENNSYLVANIA. 

Franklin  county  limonile  banks. 

Shirley's  run  is  the  county  line  between  Cumberland  and 
Franklin.  Furnace  run,  a  mile  further  S.  W.,  flows 
parallel  to  it,  out  of  the  South  mountain  down  to  Shippens- 
burg.  Means'  bank;  RoTiref 's  bank,  Gogerihauer'1  s  bank, 
are  three  small  abandoned  ore  pits  4  m.  up  the  run  from 
the  railroad. 

The  Ruby  (or  Plaster}  bank,  Southampton  bank  close  to 
Southampton  furnace,  Koser  bank,  and  Cressler  bank,  are 
ranged  along  the  run  westward,  down  stream.  The  Ruby 
bank  is  about  1200'  W.  of  the  foot  of  the  mountain,  in  the 
slates. 

The  old  Southampton  bank  is  in  the  slate  range  ;  aban- 
doned since  1865;  150'x50'x20'  deep  to  standing  water ;  cold- 
short ore.* 

From  the  last  (Furnace  run)  group  of  mines  southward 
(six  miles)  to  the  Gettysburg-Chambersburg  turnpike  there 
are  no  mines.  Here  the  face  of  the  mountains  is  set  back 
(first)  four  miles,  and  then  runs  on  to  Mont  Alto  furnace, 
4^  miles.  The  first  (northernmost)  mine  of  the  Mont 
Alto  group  is  H  ni.  S.  of  the  pike  ;  the  rest  of  them  occupy 
the  remaining  3  miles. 

The  west  face  of  the  South  mountains  south  of  the  pike 
is  called  the  White  Rock  mountain.  In  front  of  it,  south 
of  the  pike,  standing  out  in  the  limestone  valley,  is  a  low 
ridge,  a  mile  long,  called  Little  mountain,  and  between  the 
two  is  a  narrow,  shallow  vale  (opening  southward)  called 
English  valley  ;  six  mines  are  behind  Little  mountain,  two 
on  its  slopes  and  five  in  front  of  it,  at  its  west  foot. 

Little  mountain  is  an  anticlinal  of  Primal  Upper  slates, 
on  sandstone,  sinking  west  beneath  the  limestones  of  the 
valley  towards  Chambersburg,  and  east  beneath  the  lime- 
stone in  the  English  vale  (which  is  synclinal)  to  rise  again 
at  the  foot  of  White  Rock  mountain.  This  accounts  for 
the  arrangement  of  this  Pond  Bank  group. 

*Iron,  45.55;  mang.,  0.73 ;  sulp.,  0.013;  sil.  mat,  16.46;  phos.,  0.69.  The 
Ruby  analysis  reads  :  37.2  ;  1.64  ;  0.03  ;  24.25  ;  0.61. 


FRANKLIN  CO.  LIMONITE  BANKS.  249 

Mont  Alto  limonite  banks. 

Pond  bank,  a  large  abandoned  open  mine  80'  deep,  ore 
superior,  under  10'  to  30'  stripping.  A  shaft  north  of  it 
went  through  the  following :  Earth  and  white  clay,  10'; 
sand,  sharp,  light  colored,  5';  clay,  sand  and  pigment,  25'; 
black  clay,  fine-grained,  V;  lignite,  4';  clay,  sandy,  grey, 
1';  lignite,  18';  sand,  I/;  clay,  variegated,  6'.  (Wiestling's 
report  to  d' Invilliers%  1886.)* 

Little  Pond  bank,  600'  N.  of  Mont  Alto  railroad,  close  to 
base  of  Little  mountain,  formerly  an  open  cut,  afterwards 
won  by  under-ground  gangways  driven  S.  from  the  shaft 
to  the  railroad,  and  curving  round  the  Little  mountain 
anticlinal  on  a  very  flat  dip  ;  also  northward  under  the  old 
open  cut  (which  was  35'  deep.)f 

English  mine,  a  little  higher  up  the  W.  flank  of  Little 
mountain  ;  open  cut,  200'xl50'x30'  deep  to  standing  water 
(1886).  More  lump  ore  was  got  from  this  than  from  any 
other  of  the  Mont  Alto  mines,  but  it  carries  more  phos- 
phorus than  any  other,  and  so  work  was  abandoned  when 
Bessemer  pig  came  into  demand,  as  so  many  others  of  these 
limonite  banks  have  been  for  the  same  reason.:}: 

Hope  trial  pits ;  1200'  N.  E.  from  last  and  rather  on  the 
E.  slope  of  Little  mountain.  Ore  found  to  be  phosphorous 
(0.464). 

Promise  bank,  in  the  vale  on  the  White  Rock  mountain 
foot  slope  ;  actively  worked  in  1886  for  Mont  Alto  furnace ; 
first  by  open  cut,  125/xl25/x40/ deep ;  then  central  shaft 

*  I  saw  lignite  in  this  bank  in  1872,  and  reported  it  to  the  Amer.  Phil.  Soc. 
Proceedings  Jan.  3,  1873.  comparing  it  with  the  well  known  lignite  mass 
in  the  Brandon  iron  mine  in  Vermont,  and  arguing  from  it  the  tertiary  age 
of  all  the  limonite  deposits  of  the  Atlantic,  so  far  as  they  were  cavern  deposits 
in  /Silurian  limestone  valleys.  This  assigned  age,  however,  does  not  in  any 
way  conflict  with  the  theory  of  the  genesis  of  the  limonite  from  the  dam- 
ourite  or  hydromica  slates  of  the  Primal  series. 

t  Two  analyses:  Iron,  50.55  (48.60) ;  mang.,  0.300  (2. 154) ;  sulp.,  0.054  (0.048) ; 
sil.  mat.,  11.52  (11.68);  phos.,  0.157  (0.059).  McCreath. 

J  Dip  of  ore  gentle  but  decidedly  S.  E.  into  Little  mountain,  which,  as  in 
other  such  instances,  requires  explanation.  Ore  covered  with  black  clay, 
over  which  is  6'  to  10'  of  stripping.  Plenty  of  ore  left  in  this  mine.  Analysis: 
Sulp.,  0.015;  phos.,  e.849. 


250  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

70'  deeper  through  wash  ore,   and  5'  into  bottom  lime 
stone.  * 

Guilford  mine,  active  in  May,  1887,  1  m.  S.  of  last; 
same  relative  position.  Between  them  are  the  abandoned 
Westling  (1).  Limekiln  (2),  and  Calliman  (3)  banks.  The 
White  Rock  banks  (4)  is  high  up  the  mountain  slope,  and 
does  not  belong  to  the  slate  range,  but  to  the  underlying 
sandstone,  and  consequently  shows  the  highest  percentage 
of  phosphorus  ;  whereas  the  Limekiln  ore  was  almost  free 
from  phosphorus,  f 

The  Guilford  bank  was  (in  1887)  150'xlOO'x20'  to  30'  deep; 
ore  found  on  top  of  flat  ridge  a  little  W.  of  the  base  of  the 
mountain,  and  consequently  has  little  stripping,  say  4'  to 
10.':{:  Ore  stopes  largely  cut  up  with  lean  clays.  More 
bombshell  ore  has  been  got  here  than  anywhere  else.§ 

The  line  of  ore  ground  described  above  extends  S.  to  the 
RR.  1200'  and  crosses  it  into  the  B.  George  land.|| 

The  Jacob  Rock  bank  here  is  worked  solely  underground 
for  Mont  Alto  furnace. T  No.  3%  bank,  on  road.  If  m.  N. 
of  Mont  Alto ;  worked  in  1887 ;  i  acre  ;  small  lump  and 
wash  ore  plenty  ;  much  free  silica  to  be  picked  out  from 
ore  near  surface  ;  none  in  the  deeper  ore,  where  clay  takes 
the  place  of  sand  ;  15  to  20  tons  (washed)  ore  per  day. 

Ruth  shaft.     A  ridge  £  m.  N.  W.  this  last  bank  (32)  and  a 

*Two  tunnels  diverge  into  the_mountain,  from  which  gangways  branch  in 
various  directions.  (See  description  by  d'Invilliers  in  An.  Rt  1887,  p.  1432.) 
In  one,  two  beds  of  ore  27'  and  40'  thick  are  separated  by  13'  of  barren  clay 
Total  proved  thicknes^s  of  good  wash  ore  ground  in  cut  and  under-ground 
works  about  100'.  The  wash  ore  turns  out  a  percentage  of  sandstone  frag- 
ments about  as  large  as  the  largest  ore  lumps.  These  are  hand  picked  and 
thrown  aside.  Analysis:  Iron,  54.6;  mang.,  0.336;  sul.,  0.037;  sil.  mat, 
5.775;  phos.,  0.104. 

f  Analysis  show  phosphorus  in  (1)  .087;  (2)  .040;  (3)  .070;  (4)  .109. 

JThe  heavy  stripping  ground  has  had  as  much  to  do  with  the  abandonment 
of  our  limonite  mines  as  any  variety  in  the  quality  of  the  ore  ;  most  of  them 
still  retaining  large  quantities  of  ore  which  the  iron  market  will  not  pay  to 
uncover.  It  is  this  that  has  driven  the  miners  into  the  new  style  of  under- 
ground driving. 

§  These  bombs  are  very  rich  in  iron,  but  hold  so  much  clay  that  they  have 
to  be  smashed  to  pieces  and  washed. 

||  To  the  northward  the  abandoned  McNeal  bank  and  T.  Stevens'  Pond 
bank  carry  the  ore  to  the  turnpike. 

1  Analysis:  Iron,  47.35;  mang.,  0.75;  sul.,  0.066;  s.  m.,  16.02;  phos.,  0.197. 


MONT  ALTO   LIMONITE   BANKS.  251 

mile  from  the  mountain,  and  in  prolongation  of  Little 
mountain  (southward),  is  largely  slate  carrying  a  good 
deal  of  surface  ore.  A  dry  shaft  on  the  crest  of  this  ridge 
went  down  in  ore  (with  a  few  pieces  of  limestone  and  clay) 
120'.  The  ore  crop  traced  north  is  150'  wide,  almost  all 
wash  ore.  Want  of  water  has  prevented  the  establishment 
.of  a  mine  on  this  ridge.  Limestone,  vertical  (slightly  S. 
E.,  i.  e.,  overthrown),  crops  out  a  short  way  from  the  crest 
down  on  the  N.  W.  flank  of  the  ridge ;  which  fixes  the 
geological  place  of  the  slates. 

The  Mont  Alto  banks,  1,  2,  8,  4,  5,  are  almost  a  contin- 
uous open  cut,  9  m.  S.  E.  of  Chambersburg  on  the  west 
foot  slope  of  the  White  Rock  mountain  ;  served  by  a  RR. 
siding  from  the  Mont  Alto  RR.  which  runs  from  near 
Scotland,  south,  past  Mont  Alto  furnace,  to  join  the  Balti- 
more and  Cumberland  Valley  RR.  near  Waynesborough.* 

No.  1,  near  the  furnace,  long  abandoned ;  now  used  as  a 
sand  guarry,  the  outcropping  sandstone  (to  which  the  ore 
belonged)  disintegrates  and  falls  to  sand. — No.  3,  a  little 
further  on  (N.)  close  to  W.  side  of  terrace;  400'x300'x60'  to 
100'  deep  ;  "worked  to  120'  deep  ;"  now  abandoned. f— No. 
4,  next  it,  along  the  terrace  ;  60'  deep  ;  output  (of  15  years) 
100,000  tons,  all  neutral  ore,  the  main  reliance  of  the  fur- 
nace formerly  ;  not  very  rich,  but  very  free  from  siliceous 
stuff. — No.  8,  1  m.  N.  of  furnace,  on  the  same  terrace; 
crescent  shaped,  500'xl50';  everywhere  20'  to  30'  of  strip- 
ping; stopped  in  1883  ;  shaft  passed  through  30'  stripping 
and  then  70'  of  ore.  No  limestone  seen  here  ;  but  the  dip 
is  S.  E.  into  the  mountain. 

Smith  and  Awry  bank,  I  m.W.  of  Mont  Alto,  W.  of  RR. 
in  limestone  land;  1  acre,  15'  to  30'  deep,  increasing  north- 
ward ;  idle  in  1887 ;  too  much  phosphorus  for  the  Mont 
Alto  charcoal  iron  (0.415). 

Mill  bank ;  RR.  cuts  (25'  deep)  through  it,  500'  long, 

*  For  description  of  furnace  see  An.  Rt.  1887,  p.  1422 ;  and  interesting  de- 
tails in  Frazer's  Rt.,  02,  1875,  p.  257,  et  seq. 

t  A  dome-shaped  outcrop  of  limestone  shows  in  it  apparently  dipping  S.  E. 
into  the  mountain,  around  which  the  ore  was  quarried.  A  shaft  50'  deep 
wholly  in  lump  ore,  dipping  steep  towards  the  mountain,  pinching  out  E. 
and  W. 


252  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

with  nests  of  ore  in  decomposed  lime  shales ;  too  much 
phosphorus  (0.439);  abandoned. 

O.  Rock,  Pass  orchard^  and  Douglass  banks  are  small 
deserted  pits  at  the  base  of  the  mountain,  3  m.  S.  of  Mont 
Alto  and  £  m.  E.  of  Quincy  station.  They  belong  to  the 
Primal  Sandstone  range. — The  R.  MoCleary  bank,  2  m. 
W.  of  them  is  in  the  open  limestone  country  ;  150/x50'xl5/ 
deep,  with  limestone  in  its  center  dipping  25°,  S.  70°  E. 
Four  shafts  in  it  (now  all  shut)  showed  that  the  ore  was 
chiefly  pipe  ore  finely  disseminated  through  yellow  clay. 

There  are  no  mines  further  south  to  the  State  line,  but 
the  same  kind  of  ores  follow  the  foot  of  the  Blue  Ridge 
through  Virginia  and  Tennessee  ;  as  in  the  opposite  direc- 
tion similar  large  limonite  mines  range  northeastward 
through  New  Jersey  and  New  York  to  the  famous  Salis- 
bury mine  at  the  N.  W.  corner  of  Connecticut,  and  the 
Brandon  mine  in  Vermont ;  and  it  is  not  to  be  doubted 
that  if  the  damourite  slates  had  been  brought  to  the  sur- 
face anywhere  in  Middle  Pennsylvania  similar  deposits  of 
limonite  would  have  been  created  from  them  in  recent 
times  ;  but  the  general  erosion  has  not  gone  .deep  enough 
for  that,  and  the  slate  formation  has  been  as  yet  protected 
from  decomposition,  so  that  it  seems  useless  to  bore  or 
sink  for  the  limonite  beneath  the  surface.* 

Path   Valley  limonite  mines. 

The  Richmond,  Carricksfurn  and  Fannettsburg  ore  banks 
in  Path  Valley,  northern  Franklin  county,  are  perhaps  an 
exception  to  this  statement.  They  are  situated  along  a 
great  fault,  which  is  not  perfectly  well  understood,  and 
which  may  possibly  bring  the  Primal  slate  to  the  surface, 
in  which  case  the  mines  would  belong  to  the  lower  damourite 
range.  But  the  fault  more  probably  merely  throws  the 
upper  damourite  slate  against  the  Medina  sandstone  on 
the  slope  of  the  Path  mountain.  The  first  theory  is  made 

*  In  none  of  the  middle  counties  of  Pennsylvania  do  the  Primal  slates 
rise  to  the  surface  except  perhaps  at  the  Tyrone  forges  on  the  Little  J  uniata 
in  Huntingdon  county,  where  no  limonite  deposits  appear.  If  present  they 
would  greatly  assistin  identifying  the  Tyrone  beds,  over  the  precise  horizon 
of  which  hangs  some  obscurity. 


THE   TWO    VIRGINIA    RANGES.  253 

a  little  less  improbable  from  the  general  absence  of  heavy 
limonite  deposits  along  the  limestone-slate  contacts  of  Cum- 
berland and  Franklin  counties,  and  also  in  the  back  valleys 
except  at  Leathercracker  in  Blair  county.* 

The  two  Virginia  ranges. 

In  Virginia  there  are  recognized  two  distinct  ranges  of 
limonite  deposits  :  (1)  A  tower,  massive  and  dense,  dark 
and  often  pitchy  black  ore,  in  the  body  of  the  Primal  sand- 
stone ;  (2)  An  upper,  richer,  more  cellular,  brown  or  liver- 
colored  ore,  in  the  overlying  slates. 

The  lower  ores  are  usually  more  cold-short.  Both  the 
Virginian  ores  seem  to  be  richer  in  iron  with  less  silica  than 
the  general  average  Cumberland  county  ores  in  Pennsyl- 
vania. The  lower  range  is  scarcely  recognizable  in  Penn- 
sylvania ;  but  Mr.  d'Invilliers,  who  is  well  acquainted  with 
the  Virginia  ranges,  refers  to  the  lower  range  the  ore  in 
Thad.  Stevens' s  bank,  north  of  his  furnace  on  the  Cham- 
bersburg  pike,  and  the  ore  opened  in  the  face  of  the  mount- 
ain opposite  the  pike  W.  of  the  furnace.  These  I  have 
already  placed  in  the  South  Mountain  quartzite  formation, 
over  the  conglomerate  beds,  and  they  can  have  no  near 
relationship  to  the  hydromica  (damourite)  slates  at  the 
bottom  of  the  limestone,  nor  to  the  Chiques  quartzite  under 
the  slates. 

But  quartzite  beds  occur  in  the  body  of  the  chlorite  slate 
formation  in  York  county  south  of  Wrightsville,  on  the 
Susquehanna  ;  and  there  may  be  other  such  horizons  of 
quartzite  older  than  that  of  the  Chiques  Rock.  (Prazer  in 
C,  p.  202.)  Codorus  ore  (No.  43  of  the  York  Co.  map)  in 
North  Codorus  township,  may  be  of  this  case. 

GruWs  Cadorus  ore  in  quartzite. 

The  Grubb  ore  (No.  110  of  the  map,  also  called  the  "6V 
dorus  ore  bank"}  on  the  Codorus  furnace  lands  5  m.  N. 

*  The  Path  Valley  fault  discovered  and  studied  by  Dr.  A.  A.  Henderson 
of  the  First  Survey  in  1839,  1840,  is  described,  from  his  notes,  by  Prof. 
Rogers,  in  Geo.  Pa.,  1858,  Vol.  1,  p.  322,  where  Henderson's  sections  make 
the  first  theory  almost  a  certainty.  I  therefore  postpone  the  description  of 
this  ore  range  to  its  geological  place  in  a  future  chapter. 


254  GEOLOGICAL  SURVEY   OF   PENNSYLVANIA. 

of  W.  of  Wrightsville  is  remarkable  for  belonging  to  the 
Chiques  (Hellam)  quartzite  formation  itself.  Discovered 
and  opened  in  1866,  this  iron-bearing  sandstone,  quarried 
to  the  extent  of  2000  to  3000  tons  per  annum  for  St.  Charles 
Furnace  above  Columbia,  to  mix  with  Cornwall  ore,  holds 
its  iron  in  the  shape  of  ^  magnetite  and  f  red  arid  brown 
hematite;  and  having  no  sulphur  and  very  little  phos- 
phorus helps  to  make  excellent  bessemer  pig.* 


The  following  description  of  what  Dr.  Chance  considers 
a  Potsdam  sandstone  ore  mine  is  very  interesting  and 
geologically  useful. 

LehigTi  Mountain  Mining  (70.' s  limonite  mines,  2  m.  E. 
of  Emaus,  Lshigh  county,  and  next  E.  of  the  Kemmerer 
mine ;  shaft  85'  deep ;  cross  cuts  at  55'  and  85'  south  to 
ore  body  dipping  steep  (4o°±)  N.  W.  away  from  the 
mountain  towards  the  edge  of  the  limestone  (200'  to  500' 
distant);  ore  bed  varies  in  thickness  from  40'  to  5';  some- 
times pinched  out  altogether;  hanging  wall  clay  having 
layers  of  flint  and  sometimes  large  masses  of  quartzite ; 
foot  wall  also  clay  ;  mine  down  130'  (1885);  ore  40  to  50  per 
cent  iron,  rather  high  in  phosphorus  and  silica ;  probably 
an  altered  pyrite  ;  alteration  may  not  descend  beyond  300' 
where  the  drainage  level  of  the  Little  Lehigh  creek  will  be 
reached.  Outcrop  line  of  2  miles  proved  by  15  to  18  old 
surface  pits,  abandoned  because  of  continual  sliding  into 
them  of  large  quantities  of  quartz  fragments  and  sand  from 
mountain  slope  above,  making  it  impossible  to  get  clean 
ore  for  market.  Now  only  the  clean  ore  mass  is  taken  out. 
The  ore  bed  seems  to  be  faulted  at  intervals  so  as  to  present 
a  number  of  short  S.  S.  W.  crop  lines  arranged  in  echelon 

*  The  Grubbs  wrote  that  a  mixture  of  }  this  Codorus  ore  with  £  Chestnut 
Hill  and  Cornwall  ores  made  a  soft,  strong  and  very  fluid  iron.  Cornwall 
ore  contains  too  little  silica  (6  per  cent  alumina  to  15  per  cent  silica), 
whereas  J.  B.  Britton  found  in  this  Codorus  ore:  Iron  protox.,  4.13; 
sesquiox.,  36.08;  (=iron,  28.46);  ox.,  17.16;  sil.,  33.80;  al.,  4.61;  lime,  0.05; 
phos.  acid,  0.158.  For  description  of  mine  and  mining  statistics,  see  Frazer, 
Report*;,  p.  64,^1874. 


LEHIGH    MTN.    M.    CO.    LIMONITft   MINE.  255 

along  the  S.  W.  normal  line  of  the  mountain  slope  rocks, 
viz :  quartzite  lying  on  gneiss.  The  gangway  levels  also 
are  not  straight  but  curved,  the  dip  changing  from  steep  to 
flat.  Exceptions  to  the  N.  W.  dip  have  been  reported. 
(Letter  of  Dr.  H.  M.  Chance,  Nov.  3,  1885.) 

Copious  and  precise  descriptions  of  the  various  Primal 
(Potsdam)  quartzite,  sandstone  and  slate  outcrops,  expos- 
ures and  cuts  will  be  found  on  pages  99  to  135  of  Chapter 
IV,  of  D'Invilliers'  Report  on  Berks  county,  D3,  Vol.  1. 


256  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 


CHAPTER  XXI. 

Magnetic  limonite  mines  doubtfully  referred  to  the  Primal 
slates,  or  to  the  Gneiss,  or  to  the  Trias,  in  York,  Chester 
and  Berks  counties. 

The  wording  of  this  title  is  not  intended  to  express  more 
than  the  fact  that  the  magnetic  limonites  of  York,.  Chester 
and  Berks  are  so  curiously  many-sided  in  their  relations  to 
the  rock  formations  in  and  upon  which  they  lie,  that  it  is 
in  the  case  of  most  of  them  impossible  to  prove  satisfac- 
torily that  they  have  originated  from  the  decomposition  of 
iron-bearing  shales  of  a  particular  age.  They  have  all  been 
changed  from  the  condition  of  a  hydrous  peroxide  to  that 
of  an  anhydrous  sesquioxide  by  the  heat  of  trap  dykes. 
How  far  the  trap  has  introduced  iron  (with  copper)  from 
below,  or  how  far  the  action  of  the  trap  has  been  limited 
to  segregating  the  iron  distributed  in  the  sedimentary  strata, 
cannot  be  dogmatically  stated.  The  prime  fact  is  that  the 
region  of  these  mines  is  a  belt  of  country  covered  now,  or 
once  covered,  by  the  Trias  formation,  the  special  (but  not 
exclusive)  region  of  trap  outflows. 

In  JorJc  county. 

The  Dillsburg  magnetic  mines,  situated  in  the  north- 
western quarter  of  York  county,  two  miles  from  the  foot 
of  the  South  Mountains  and  a  mile  more  or  less  E.  of  Dills- 
burg,  in  the  Trias  belt,  form  a  group  over  which  has  been 
some  geological  contention  as  to  what  formation  they 
belong  to,  whether  to  the  South  mountain  cambrian  rocks,  or 
to  the  Trias  new  red  sandstone  and  shale.  All  the  mines  yield 
about  the  same  kind  and  quality  of  ore,  magnetic,  sulphur 
and  copper  bearing,  like  the  Cornwall,  Jones  and  Warwick 
ores.  It  is  a  country  of  trap,  and  dykes  of  trap  adjoin  the 
ore  ;  which  accounts  for  the  copper,  sulphur  and  magnetite. 
But  the  Valley  limestone  No.  II  is  close  at  hand  on  Yellow 
Breeches  creek,  overlaid  by  Trias ;  and  a  belt  of  Hudson 


MAGNETIC   LIMONITE   MINES   IN   YORK   CO.  257 

River  slate  No.  .Ill,  in  Cumberland  county,  points  directly 
towards  Dillsburg,  not  3  miles  distant.  The  country  north 
of  the  Trias  in  Cumberland  has  parallel  synclinal  basins  of 
III  separated  by  anticlinals  of  the  underlying  II.  There 
can  be  little  reason  to  doubt  that  the  Trias  in  York  county 
covers  other  and  similar  parallel  rolls  of  II  and  III ;  and 
therefore  it  is  entirely  proper  to  suppose  the  existence  of 
the  lime  shales  between  II  and  III  (the  upper  damourite 
slates)  beneath  the  Trias  at  and  around  the  Dillsburg  mines. 

The  situation  then  would  be  precisely  that  of  the  Corn- 
wall mine,  except  that  at  Cornwall  the  great  fault  has  let 
the  Trias  down  against  the  II-III  slates.  But  there  may 
be  faults  at  Dillsburg  also  ;  and  indeed  both  the  great  abun- 
dance of  trap  and  the  general  north  dip  of  the  Trias  pre- 
suppose them. 

On  the  other  hand,  between  the  Dillsburg  mines  and  the 
mountain  slope  (covered  with  hydromica  slates  and  frag- 
ments of  Chiques  quartzite)  the  Primal  upper  slates  should 
exist  beneath  the  Trias,  and  should  furnish  Chestnut  Hill 
ore,  turned  by  trap  into  Jones  Warwick  ore. 

The  limestone  dips  being  all  steep,  the  cross  section  dis- 
tance between  the  upper  and  lower  slates  need  nowhere  be 
more  than  a  mile  (on  a  monoclinal);  and,  therefore,  if  the 
Dillsburg  ore  be  transformed  damourite  slate  limonites  they 
may  belong  to  either  the  upper  or  the  lower  slates  ;  and  in 
either  case  the  trap  would  make  them  copper-bearing  mag- 
netic red-short  ores. 

But  as  most  of  the  numerous  mines  are  to  all  appearance 
in  Trias  rocks  they  have  been  assigned  to  iron-bearing  slates 
of  Trias  age,  altered  by  trap.  If  the  McCormick  boreholes 
near  Dillsburg  furnish  accurate  data  they  make  it  certain 
that  some  at  least  of  the  Dillsburg  ore-masses  are  true  ore- 
beds  lying  between  variously  colored  sandstone  strata,  and 
not  far  above  and  below  beds  of  limestone  and  sheets  of  so- 
called  white,  grey  and  black  trap.*  If  these  rocks  be  of 
Trias  age  it  seems  quite  impossible  to  assign  the  ores  of 

*  See  borehole  records  (condensed)  in  foot  note  to  page  ;  and  in  full  in 
C2,  p.  216. 

17 


258  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

the  Dillsbnrg  district  to  the  Primal  slates.  The  most  im- 
portant mine  for  this  side  of  the  argument  is  that  of  the 
Altland  shaft  or  Schoolhouse  mine.  The  most  important 
for  the  other  side  are  the  Bender  and  McCormick  banks. 

The  central  figure  of  the  Dillsburg  group  is  the — 

Underwood  slope  (formerly  Mumper  mine),  opened  1848; 
slope  290'  long,  28°  (average)  due  N.;  at  26'  struck  ore  18' 
thick  ;  followed  it  dipping  more  steeply  ;  roof  trap  ;  floor 
"sandstone  intermixed  witli  limestone";  distance  from 
wall  to  wall  "averages"  5';  but  ore  6'  to  30'  thick  met 
with  ;  8  side  drift  levels  averaging  70'  in  length  ;  3  shafts, 
deepest  140';  output  (1875)  40  tons  per  day,  total  output  to 
date  (1875)  say  10,000  tons  ;  ore  solid  and  hard,  blasted.- 
very  little  of  it  crystallized  magnetite.* 

Underwood's  new  mine;  2CO'  S.  of  old  slope;  one  pit 
10,000  square  feet,  15'  deep  ;  a  derrick  shaft  went  through 
25'  (20'?)  trdp  and  then  28'+  (30'?)  ore  ;  E.  and  W.  level ; 
slope  from  bottom  of  shaft  50'  long,  gentle  N.  dip  in  ore ; 
6  tons  a  day.  '  1A  layer  of  limestone  was  passed  througli" 
Ore  needs  no  washing.  South  of  derrick  shaft,  70',  another 
shaft  through  2'  trap,  then  10'  ore. — E.  N.  E.  of  derrick 
shaft,  100',  a  third  shaft,  same  record. — New  pit  sunk 
through  soil  and  gravel  30'  to  ore. — A  large  pit  S.  W.  of 
main  pit  exhausted  a  pot  of  5000  tons  of  surface  ore. — E. 
of  S.  300',  a  third  pit  (3500  sq.  ft.)  abandoned. 

Logan's  mine,  500'  E.  by  N.  of  Underwood's  slope; 
opened  in  1874  ;  shaft  50'  deep  ;  slope  from  bottom  of  shaft 
28°,  due  N.  80'  long  (1815);  output  25  tons  per  day  for  H. 
McCormick  furnaces  at  Harrisburg ;  ore  magnetic,  not 
washed;  section,  soil  and  gravel  with  some  bowlders  of 
trap,  28';  sand,  6';  ore  20';  floor  rock  2'.f 

King's  mine,  3300'  E.  of  Underwood's  slope  ;  shaft  sunk 
(1876)  through  soil  and  loose  trap,  6' ;  hard  trap,  17' ;  ore, 
9'.  A  level  driven  20'  E.  in  ore  wedged  between  trap  below 
and  hardened  sandstone  above,  dipping  (elsewhere)  23°,  N. 

*  Lowest  gangway  110'  long  E.  and  120'  W.  See  full  description  of  work- 
ing and  statistics  of  cost,  etc.,  in  Frazer's  C2,  p.  208. 

|  Statistics,  etc.,  in  C2,  p.  211.— A  trial  shaft  2400'  N.  proved  some  ore; 
ground  strewn  with  large  bowlders  of  trap. 


MAGNETIC   LIMONITE  MINES   IN   YORK   CO.  259 

40°  W.  As  this  mine  was  advanced  (spring  of  1876)  the  ore 
steadily  improved  in  quality  downward,  pyrites  diminish- 
ing, lime  and  magnesia  increasing,  and  vein  more  solid. 
The  vein  is  9£'  thick,  viz :  bottom  ore,  1$' ;  rock,  V ;  top 
ore,  7'.  Output  25  tons  per  day.* — Other  old  pits  are  to  be 
seen  in  the  neighborhood  (exhausted  ore-pots)  one  of  which 
is  said  to  have  given  2000  tons  of  surface  wash  ore,  with 
some  N.  slope  ore.  Massive  trap  is  still  visible  in  the  pit. 

McCormicJc  &  Co.' sold  mine,  500'  E.  of  the  Underwood 
slope  ;  12,000  square  feet  area  ;  begun  by  Mumper  in  1850 ; 
shaft  (in  bottom  of  pit)  140'  deep ;  ore  exhausted.  A  slope 
100'  N.  of  pit,  20°,  60'  long,  abandoned. 

McQormicK  s  long  cut  and  slope  ;  the  mine  furthest  north 
in  this  group  ;  open  cut  along  ore  crop  500' ;  roof  trap,  dip- 
ping 27°  to  34°  (20°,  Altland)  N.  Westward.  Abandoned 
(1875).f 

Smyser's  open  cut,  1000'  S.  E.  of  Underwood  slope;  ore 
like  that  of  the  other  mines  ;  total  yield,  3000  tons  ;  pit  30' 
deep  in  sand  and  gravel  (no  rock  visible),  abandoned.:}: 

BeWs  sJiaft,  33'  deep,  not  far  from  bore  hole  No.  3.§ 

*  Mr.  King's  letter,  May  22,  1876.  He  explains  that  the  "fault  rock  "  is  "a 
mixed  up,  broken  up  mixture  of  sandstone  and  trap  rock,"  and  that  imme- 
diately behind  it  (S.)  is  a  ridge  of  dark  green  rock.  See  contents  of  letter 
in  C2,  p.  213. 

fBore  hole  No.  1,  160°  N.  W.  of  middle  of  this  cut,  went  down  through 
clay,  sandstone  and  clay,  14';  bastard  limestone,  9|' ;  sandstone,  9|';  trap, 
9' ;  unknown  and  brown  sandstone,  32' ;  ore,  6'  ;  sandstone,  4'  ;  lean-ore,  4' ; 
total,  88'.— Bore  hole  No.  3  ;  white  and  red  sandstone,  17' ;  trap,  17|' ;  black, 
green,  brown  and  white  sandstones,  14^' ;  total,  49  .—Bore  hole  No.  4,  150'  S. 
of  E.  end  of  cut;  various  colored  sandstones,  50';  trap  (black),  16'  and 
(white)  63' ;  ore,  1|'  ;  white,  green  and  red  sandstones,  42' ;  total,  116'. — Bore 
hole  No.  5,  sunk  in  the  old  bank  :  soil,  &c.,  9' ;  ore,  £' ;  sandstones,  22' ;  trap 
(black),  23' ;  sandstone,  3£' ;  ore,  3|  ;  white  sandstone,  5' ;  ore,  1  \' ;  white  sand- 
stone, 11' ;  limestone  and  flint,  6' ;  limestone  and  fireclay,  10'  ;  sandstones, 
30' ;  ore,  2' ;  sandstone,  2'  ;  sandstone  and  ore,  3'  ;  limestone  and  flint,  6?' ; 
ore  and  sandstone,  Og' ;  sandstones,  17'  ;  trap  (grey),  2' ;  white  sandstone,  2' ; 
limestone,  3' ;  variously  colored  sandstone  beds,  25' ;  total,  191'.  See  these 
records  in  more  detail  in  C2,  p.  216. 

J  One  report  says  that  the  lessees  sank  45'  to  ore  25'  thick  dipping  S.  E. 
Another  report  makes  the  ore  dip  S.  W.  on  a  saddle  of  trap.  Ore  used  un- 
washed ;  scattered  through  the  bank  ;  costly  mining.  Two  observers  could 
get  no  dip  for  the  trap  in  this  bank.  C2,  p.  217. 

§  These  works  were  new  when  visited  in  1875.     See  details  in  C2,  p.  218. 


260  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

Grove's  mine,  f  m.  S.  E.  of  Underwood  slope  ;  worked  for 
2  years  previous  to  1875*. 

Price's  open  cut,  a  mile  S.  E.  of  Underwood  slope  ;  350' 
long  by  125'  broad,  abandoned  about  1860,  after  yielding  a 
large  amount  of  magnetic  ore  ;  said  (in  1875)  to  have  still  a 
6'  ore  bed  within  14'  of  surface  ;  sandstone  appears  in  the 
N.  side. 

Fuller  mine,  3£  m.  N.  E.  of  Dillsburg ;  begun  1863  ; 
worked  in  1875,  15  tons  per  day  ;  ore  strongly  magnetic  ; 
tunnel  adit  from  railroad  on  bank  of  Yellow  Breeches  creek, 
200'  due  S.  and  two  drifts  E.  and  W.  under  roof  of  trap,  dip- 
ping 24°,  N.  W.  ;  foot  wall  greenish  altered  sandrock.f 

Porter's  bank,  near  the  last ;  worked  by  G-ov.  Porter  five 
years  (from  1850  -J-  ?)  and  by  A.  Price  for  eight  years  ;  ore 
magnetic ;  pit,  40'  deep  (14'  below  creek  level) ;  ore  dipped 
30°  towards  and  under  the  creek ;  limestone  beds  in  RR. 
cut  close  by  dip  30°,  S.  10  E°.% 

Shelly' s  mine,  near  the  last,  yielded  300  tons  of  magnetic 
ore,  10'  thick,  under  20'  of  trap,  and  lying  on  Potomac 
marble.  Another  shaft  went  through  30'  of  trap  to  ore.§ 

A  group  of  pits  and  shafts  S.  W.  of  Dillsburg,  includes 
Heiges'  sJiaft,  very  little  ore; — Filler's  trial  pit ;  Berg- 
hart's  pit,  a  layer  of  ore  between  red  sandstone  (Trias); 
— H.  Heiges'  trial  pits-, — A.  Heiges  pits,  ore  and  trap  ; — 
G.  Heiges'  shaft,  30'  through  trap  and  green  sandstone  ; 
ore  4'  thick.  All  these  are  scarcely  more  than  unsuccess- 
ful prospecting  holes.  Trap  is  abundant ;  the  surveying 
needle  is  deflected  ;  Primal  slates  appear  from  beneath  the 
Trias. 

Another  group  of  pits  of  small  size  range  irregularly  past 
Wellsville  (6  m.  S.  E.  of  Dillsburg)  in  the  heart  of  the  Trias 

*See  details  in  02,  p.  219. 

t  Details  and  statistics  in  C2,  p.  220.  Analysis  (in  C,  p.  74)  :  Iron  oxides, 
62.0 ;  phos.  oxide,  0.05  ;  manganese  sesqui  oxide,  0.352. 

JThe  ore  bed  is  reported  to  have  been  6'  thick,  and  opened  for  25'  along 
the  crop.  Dr.  Frazer  thinks  that  by  "magnetic"  is  not  meant  ore  of  the 
Dillsburg  type,  but  the  "magnetic"  ore  of  the  York  valley,  and  probably 
belonging  to  the  older  (Primal)  rocks  ;  Yellow  Breeches  creek  being  prac- 
tically the  dividing  line  between  these  and  the  Trias.  (C2,  p.  221.) 

§  Such  is  the  report  of  Mr.  Snelly  to  Dr.  Frazer  in  1875.     C2,  p.  222. 


MAGNETIC   LIMONITE   MINES   IN   YORK   CO.  261 

country,  with  abundance  of  trap  :  Lichty's,  Meyers',  flick- 
er's, KimmeT s,  Cooper's,  Morganthaler' s,  Wiley's,  Bren- 
neman's,  (Jr  test's,  Barman?  s,  Gerber's,  Altman's,  Com- 
fort's, Cadioaladef  s,  Bent's,  Marshall's,  Schluthauer' s, 
Cookson's,  Smith's  (W.  72.),  Smith  s  (J.  T.) ;  but  they  all 
belong  to  the  Trias,  and  not  to  the  Primal  slates  ;  as  is  best 
shown  at  the  ScJwoUwuse  mine  or  Altland  shaft,  where  the 
micaceous  magnetic  ore  bed  is  seen  regularly  interbedded 
with  the  Trias  sandstones,  dipping  35°,  N,  W.,  and  both 
sandstones  and  ore  cut  off  by  a  vertical  trap  dyke,  only 
4'  thick.  Over  5000  tons  were  won  previous  to  1875.* 

There  remain  to  be  noticed  here  a  group  of  three  mines 
undoubtedly  of  Primal  age,  at  the  foot  of  the  South  Mount- 
ain in  York  county : 

Bender' s  magnetic  ore  miney  1£  m  S.  W.  of  Dillsburg, 
on  and  near  the  edge  of  the  Trias  ;  open  cut ;  1849,  200 
tons ;  idle  until  1873,  300  tons,  a  pocket  of  ore  5'  thick ; 
other  such  shallow  pockets  near  by  ;  ore  magnetic. 

Bender's  limonite  bank,  £  m.  W.  by  N".  of  last,  in  the 
decayed  Primal  slate  clays  which  form  the  south  flank  of 
the  mountain  range  ;  open  cut,  £  acre  ;  1874  ;  output  2000 
tons  in  1£  years  and  abandoned  ;  stripping  12'  to  20',  over 
a  mass  of  small  wash  ore  and  streaks  of  shell  ore,  23'  (and 
more)  deep  ;  one  of  the  ore  layers  dipped  56°  S.  f 

McCormick' s  bank  close  to  the  last;  a  century  old;  worked 
by  many  successive  parties  ;  wash  ore ;  very  few  large 
masses  ;  dip  of  richer  streaks  same  as  in  Bender's  bank  ; 
pit  35'  deep  to  water  ;  no  rock  seen  ;  ore  left  in  floor  ;  aban- 
doned. 

*This  is  the  best  example  of  indubitable  Trias  magnetic  ore  I  know,  and 
deserves  careful  study.  The  gangway  in  ore  from  the  shaft  east  shows  the 
ore  bed  varying  between  1'  and  6',  and  sometimes  penetrating  one  side  of 
the  trap,  for  a  few  inches  only.  The  trap  has  developed  ore  on  its  N.  W 
side,  but  not  worth  mining.  (See  picture  section  in  C2,  p.  235  ;  mine  plan, 
p.  237.) 

t  But  the  decayed  slate  rock  layers  can  be  easily  followed  by  the  eye,  in 
both  banks  dipping  30°,  S.  30°  E.  Many  of  the  leaves  of  clay  are  encrusted 
with  limonite  ;  many  of  them  are  twisted  and  bent  in  common  with  leaves 
of  hard  brittle  ore  ;  showing  plainly  that  the  segregation  of  the  ore  followed 
the  decomposition  of  the  clayslate.  (C2,  p.  229.) 


262  GEOLOGICAL   SUEVEY   OF   PENNSYLVANIA. 

In  Chester  county. 

Pickering  creek  heads  at  Windsor  in  Upper  Uwchlan,  and 
flows  eastward  through  West  Pikeland  (past  Marisville), 
East  Pikeland,  Charlestown  and  Schuylkill.  to  the  river  two 
miles  below  Phoenix ville.  The  Pickering  Valley  RR.,  10 
miles  long,  brings  down  the  ores  to  the  Phoenixville  fur- 
naces. 

The  country  is  gneiss,  undoubtedly  once  entirely  covered, 
as  it  now  is  partially,  with  Primal  slates  and  sandstone ; 
and  these  of  course  with  the  limestone,  slate  and  sandstone 
formations  of  the  Palaeozoic  series  up  to  the  coal  measures. 
If  all  these  were  removed  by  erosion,  or  nearly  all  of  them, 
before  the  New  Red  series  was  laid  down  upon  the  country, 
the  interval  of  time  between  the  Carboniferous  and  Trias 
required  for  such  erosion  would  be  incredibly  great.  And 
yet  we  see  the  Trias  resting  on  the  gneiss  along  French 
creek,  with  no  appearance  of  a  fault  at  the  contact.  The 
eroded  edge  of  the  Trias  across  Chester,  Montgomery  and 
Berks  counties  is  sufficient  proof  of  the  former  extension 
of  the  Trias  south  westward  over  the  gneiss  region,  no  doubt 
over  the  whole  of  it. 

This  is  the  foundation  of  Prof.  Rogers'  theory  of  the 
Pickering  Valley  limonite  deposits,  and  of  others  north  and 
south  of  them  in  the  gneiss  country.  He  supposed  that 
iron-bearing  Trias  sandstone  beds  caught  in  faults  in  the 
gneiss  deposited  their  iron  in  ores  left  after  the  general 
erosion  of  the  Trias  had  been  accomplished.* 

But  it  is  admissible  to  suppose  that  portions  of  the  iron- 
bearing  Primal  sandstone  and  hydromica  or  damourite  slate 
formation  have  escaped  erosion  from  the  surface  of  the 
gneiss  and  have  produced  limonite  ore  deposits  here  as  else- 
where. Although  there  are  some  serious  objections  to  this 
hypothesis  (for  the  whole  subject  of  the  erosion  of  the  gneiss 
region  of  N.  Chester  is  full  of  difficulties)  it  has  some  ad- 
vantages over  the  other  ;  one  of  which  Mr.  Rogers  himself 
furnishes,  when  he  says  :  "  It  is  an  interesting  fact,  having 

*Geol.  Penn.   1858,  Vol.  1,  pp.  83  to  90,  with  diagrams  of  faults  and  ores  ; 
copied  into  Report  C4,  1883,  p.  168. 


MAGNETIC   MINES   IN   CHESTER    CO.  263 

some  bearing  perhaps  upon  the  question  of  the  origin  of 
the  iron  ores  .  .  .  that  several  of  these  deposits  adjoin,  if 
they  are  not  closely  connected  with  outcrops  .  .  .  of  lime- 
stone" as  at  the  Lewis  bank  and  the  W.  Par  Jeer  bank.  A 
still  more  important  support  to  the  theory  is  lent  by  the 
fact  reported  by  Dr.  Frazer  (04,  p.  231)  that  exposures  of 
azoic  slate  occur  in  the  Harvey  (or  Latshaw)  mine.  The 
large  Worth  mine  of  surface  limonite  in  W.  Cain,  l£m.  N. 
of  Sadsburyville,  lends  some  support  to  this  view,  as  agreed 
by  Dr.  Frazer  in  C3,  p.  261.  The  slate  partings  in  the 
limonite  magnetite  ore  mass  at  the  Warwick  mine  are  de- 
cidedly friendly  to  this  view. 

A  group  of  old  mines  around  Yellow  Springs  were  de- 
scribed by  Prof.  Rogers  as  seen  by  him  in  1853 : 

Lewis  bank,  still  worked  in  1853,  1£  m.  N".  E.  of  Yellow 
Springs;  in  narrow  trough  (fault?)  between  steep  gneiss, 
and  gently  pitching  altered  red  sandstone  and  shale  (on  N. 
W.  side) ;  white  granite  near  south  wall ;  ore  a  loose  sandy 
mass  ;  bank  N.  E.  and  S.  W.  40'  deep ;  altered  red  rock 
holds  many  spangles  of  graphite  and  magnetite  crystals  ; 
the  unaltered  red  rock  quite  like  Trias.  A  narrow  strip 
of  limestone  is  said  to  have  been  encountered  in  this  mine. 

Fegley1  s  bank,  %  m.  N.  E.  of  Yellow  Springs,  separated 
from  the  Lewis  by  a  gneiss  range ;  two  excavations  in  line, 
between  contorted  steep  gneiss  and  altered  red  sandstone 
(on  N.  W.  side)  dipping  40°,  S.  E.  ;  granite  veins  in  gneiss 
wall ;  ore  mingled  in  a  confused  mass  of  rotted  gneiss  and 
granite ;  but  main  body  of  ore  (40'  thick)  is  in  loose  earth 
resting  on  the  red  rocks.  Fegley  bank  (1853)  200'  X  100'  X 
50'  deep ;  ore  in  bottom.  Another  large  pit,  just  N.  E.  of 
the  other,  has  a  12'  ore  bed  on  a  floor  of  red  sandstone.* 
Annual  yield  of  the  two  banks  in  1853,  2400  and  2000  tons. 
Leased  to  the  Phoenix  I.  Co.  in  1865.  Abandoned. 

Latshaw  '(later  Harvey)  mine,  £•  m.  S.  W.  of  Yellow 
Springs,  on  a  fault  between  steep  gneiss  and  S.  E.  dipping 
red  rocks,  but  decomposed  granite  in  the  south  wall  ;  ore 

*The  strip  of  red  rock  makes  a  low  ridge  600'  wide  and  half  a  mile  long, 
and  the  ore  seems  to  have  come  from  it.  Mr.  Rogers  had  no  doubt  of  its 
Trias  age. 


264  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

mass  on  and  in  crushed  and  crystalline  red  rocks,  full  of 
graphite  scales  and  mica,  looking  like  gneiss.  Output  in 
1874,  2000  or  3000"  tons  (Rogers).— Output  in  1881,  1000 
tons.  Exposures  of  azoic  slates  dipping  S.  E.  occur  in 
this  mine  (Frazer). 

Steitler  ~bank,  f  ni.  S.  W.  of  the  Latshaw,  and  on  the 
same  fault,  between  a  vertical  granite  dyke  and  S.  E.  dip- 
pings crushed  red  sandstone.*  First  worked  about  1800; 
annual  continuous  output  tor  8  years  (1845  to  1853)  3000  to 
5000  tons  of  rich  good  ore  ;  a  little  manganese  oxide  ;  a 
little  pyrites  ;  beautiful  masses  of  fibrous  and  pipe  limonite 
frequent ;  unusual  abundance  of  bombshell  ore,  often  hold- 
ing feathery-white  mica  (Rogers). — In  1879  this  excava- 
tion was  900'  long,  600'  wide  ;  had  sometimes  yielded  8000 
tons  in  a  year;  but  was  then  abandoned.  (Frazer,  C4,  p.  231.) 

Raby  mine,  in  E.  Pikeland,  1  m.  S.  W.  of  Kimberly ; 
still  worked  in  1882,  6  tons  per  day. — Ornermine,  %  m.  W. 
of  old  Fegley  in  W.  Pikeland  ;  worked  by  the  Phoenix  I. 
Co.  in  1883.  Shows  graphite. — Fussel  (Morris)  mine,  1 
m.  W.  of  Yellow  Springs,  exhausted  in  1880,  after  an  out- 
put of  250  tons.—  Tustin  (Isaac]  mine,  \  m.  S.  of  Chester 
(Yellow)  Springs  ;  opened  1851  ;  leased  to  Monocacy  Fur- 
nace Co.;  then  in  1864  to  the  Phoenix  I.  Co.;  shallow  ore  ; 
abandoned. — Prizer  mine,  600'  S.  W.  of  the  last ;  worked 
by  Phoenix  I.  Co.  from  1856  ;  then  by  Monacacy  F.  Co. ; 
large  output ;  heavy  stripping  ;  abandoned. 

Acker  (E.  Jones)  mine,  \  m.  S.  of  Latshaw  (Harvey) 
mine,  was  worked  from  1863  on  by  Phoenix  I.  Co.  with  a 
large  output ;  afterwards  for  Monocacy  furnace  ;  output  in 
1882,  20  to  30  tons  a  day.  It  was  opened  about  1853,  on  a 
different  fault  line  (600'  S.  of)  the  Latshaw  fault  line,  be- 
tween steep  gneiss  and  S.  E.  dipping  altered  crystalline  red 
sandstone  beds  full  of  mica  and  specular  iron  crystals  ;  it 
was  at  that  time  a  mass  of  fragments  of  white  granite, 
gneiss,  and  red  rock  pervaded  and  cemented  by  limonite. 
See  diagram  section  in  C4,  p.  171,  borrowed  from  Rogers' 
Geol.  Pa.,  1858. 

*  See  diagram  cross  section  on  plate,  Report  C4,  p.  171,  copied  from  Rogers' 
Geol,  Pa.,  1858. 


MAGNETIC   MINES   IN   CHESTER   CO.  265 

Mosteller  mine  in  W.  Vincent,  1  m.  E.  of  Pughtown ; 
Phoenix  I.  Co.,  1880,  15  tons  a  day.  Analysis  of  ore  :  Iron 
41.64;  silica,  23.07;  phosphorus,  0.46  (J.  C.  Smith).— 
Stauffer  mine,  f  m.  S.  W.  of  last;  Phoenix  I.  Co.,  1880; 
after  4000  tons  output,  abandoned. — Green's  mine  in  W. 
Nantmeal ;  Eckert  &  Co. ;  two  large  excavations,  i  and  f 
m.  N.  W.  of  Barnestown  station,  E.  Brandywine  and 
Waynesburg  RR. 

The   Warwick  Oroop. 

The  famous  Warwick  township  mines  of  northern  Chester, 
in  the  trap  district  on  the  edge  of  Trias,  are  among  the 
most  interesting  and  obscure  of  all  our  ore  deposits,  both 
in  respect  of  their  relation  to  the  rocks,  and  in  respect  of 
the  chemical  changes  which  have  produced  the  ore.  The 
felspathic  granite  or  conglomerate  rock  at  the  Hopewell 
mines  is  very  interesting. 

The  Hopewell  Furnace  old  mine,  1$  m.  N.  W.  of  St. 
Mary's,  was  abandoned  (1878);  but  ike  new  mine,  150'  deep, 
was  worked  by  drifts  and  slopes,  at  four  levels  ;  shaft  sunk 
in  1877-8  to  ore  40'  thick  and  no  bottom,  but  said  to  average 
only  10';  ore  between  a  hanging  wall  of  conglomerate  (with 
blue  or  amethyst  quartz)  and  a  foot  wall  of  syenite  or 
dolerite  trap  ("blue  rock");  ore  much  like  Cornwall  ore; 
ore  lying  in  veins  or  bands,  dipping  35°,  N.  70°  W. ;  open  cut 
200'  long  ;  old  shaft  abandoned  ;  new  shaft  150'  to  a  12'  ore 
dipping  35°;  exhausted,  for  in  1882  they  were  robbing  the 
pillars  at  the  rate  of  30  tons  a  day  (Frazer).  The  mine  is 
near  the  contact  of  the  Primal  sandstone  with  the  gneiss. 
Shaft  sunk  through  trap,  struck  two  veins  of  magnetic  ore 
dipping  30°,  N.  25°  W.,  the  upper  one  15'  to  25'  thick,  the 
lower  one  7'.  The  trap  runs  N.  W.-S.  E.,  cutting  and 
shifting  the  ore  (Rogers). 

Warwick  mine,  at  Marysville,  a  very  large  old  work  in 
limonite  and  magnetic  ore,  no  doubt  orginally  all  limonite, 
concentrated  from  ore- bearing  rocks  obscurely  related  to 
the  upturned  gneiss,  on  the  eroded  edges  of  which  lies  the 
ore  in  a  sheet  varying  from  2'  to  17'  in  thickness.*, 

*  As  shown  in  the  diagram  section  in  C4,  p.  239,  borrowed  from  Rogers' 
fig.  572  in  Geol.  Pa.,  as  seen  in  1854.  The  ore  is  a  mixture  of  limonite  and 


266  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

This  large  .Warwick  mine  is  in  a  gravel  mass  made  up  of 
loose  fragments  of  syenite,  quartz  conglomerate,  and  mud 
rock,  mixed  with  sand  and  clay.  A  public  road  runs  through 
the  mine. 

,  The  new  Smith"1 s  Warwick  mine  was  opened  in  1879. 
In  1882  the  Brooke  I.  Co.,  the  principal  operators,  were 
taking  out  20  tons  of  magnetic  ore  per  day. 

Steele's  mine,  %  m.  N.  of  Marysville,  abandoned  long  be- 
fore 1850,  seems  to  have  been  on  a  magnetite  vein  in  gneiss 
near  a  trap  dyke.  (04,  241. ) — LeigMon"1  s  mine,  S.  of  Marys- 
ville, just  outside  the  edge  of  a  patch  of  Trias  basal  con- 
glomerate, was  largely  opened  on  the  outcrops  of  two  mag- 
netite veins  dipping  33°,  N.  W.  ;  the  upper,  15'  thick,  pinch- 
ing in  25'  of  depth  to  only  15  inches ;  the  lower  (two  or 
three  feet  beneath  the  upper)  10'  thick  at  the  surface, 
dwindling  to  4'.*  Length  of  crop  1500' ;  length  of  pit  200' ; 
depth  of  open  cut  40' ;  total  output  20, 000  tons  ;  abandoned 
before  1853. — Knauertown  mine,  on  S.  edge  of  tongue  of 

magnetite,  the  agent  of  change  being  a  wide  trap  dyke  which  passes  across 
the  ore  mass  and  throws  it  up  on  one  side.  The  ore  lies  in  several  nearly 
flat  waves.  The  edge  of  the  Trias  new  red  sandstone  formation  laps  here 
over  the  gneiss  and  the  iron  ore.  At  one  place  the  Trias  conglomerate  is 
baked  and  altered,  holding  round  bunches  of  various  crystalline  minerals, 
hollow  spaces  (geodes)  and  vein  strings.  The  geodes  are  lined  with  beauti- 
ful crystals  of  epidote,  etc.,  and  bunches  of  large  fine  garnet  (melenite). 
Injections  of  serpentine  occur  in  the  mine.  The  greatest  depth  of  the  ore 
below  the  surface  was  60  feet ;  over  much  of  the  ground  the  ore  was  but 
little  beneath  the  surface.  Average  richness  45,  rising  sometimes  to  50  per 
cent;  somewhat  sulphurous.  The  mine  has  been  wrought  for  160  years, 
with  an  annual  output  for  15  years  of  4,000  tons ;  for  the  next  20  years  6,000 ; 
in  1853,  12,000.  The  changed  ore  is  grey,  crystalline,  magnetic ;  the  un- 
changed ore  is  a  compact  closely  cemented  brown  hematite  (limonite)  as  in 
other  mines  described  in  this  chapter. 

Inter  stratified  minutely  with  the  ore  are  plates  of  earthy  hardened  slate 
or  shale,  which  sometimes  swell  to  considerable  thickness  and  separate  the 
ore  mass  into  distinct  ore  beds.  An  intimate  mixture  of  fine-grained  ore 
with  the  clay  stuff  makes  the  lower  grades  of  ore.  What  are  these  slate 
layers  ?  The  resemblance  of  Warwick  to  Cornwall  ores  suggest  that  we 
have  at  Warwick  as  at  Cornwall  a  mass  of  hydromica  slate,  or  rather  of 
lime-shales,  decomposed  into  limonite  and  then  partially  converted  by  trap 
into  magnetite.  But  at  Cornwall  the  lime  shales  are  those  at  the  top  of  III,  as 
at  Irontoii  and  Moselem.  It  is  impossible  to  imagine  any  slate  at  Warwick 
except  the  Primal ;  and  this  if  present  will  explain  the  "injections  of  ser- 
pentine" mentioned  above. 

*See  diagram  section,  Rogers'  fig.  571,  in  C4,  p.  239. 


MAGNETIC   MINES   IN   BERKS   CO.  267 

Trias  ;  small ;  ore  and  situation  precisely  like  Warwick. — 
Crossley 's  pits,  1m.  N.  of  Knauertown  ;  abandoned  before 
1854  ;  between  walls  of  gneiss  in  a  low  ridge,  at  the  W.  end 
of  which  a  large  vein  of  magnetite  rapidly  pinched  out 
downward.* — French  Creek  magnetite  mines,  \  mile  S.  of 
Harmony ville  at  the  end  of  the  St.  Peters  branch  of  W.  & 
N.  RR.  ;  two  shafts  250'  deep  (with  hoisting  and  pumping 
engines  at  both) ;  capacity  for  output,  15,000  tons  per  an- 
num. Ore  holds  sulphides  of  iron  and  copper. f 

In  Berks  county. 

The  Jones  (  Warwick]  mine  in  Caernarvon  township,  Berks 
county,  3  m.  N.  E.  of  Morgantown,  and  12  m.  S.  of  Read- 
ing, worked  by  the  Phoenix  Iron  Co.,  was  opened  by  David 
Jones  in  1735  on  a  1000  acre  tract  sold  as  mineral  land  by 
Wm.  Penn  to  Welsh  iron  masters  as  early  as  16864  It 
was  known  as  a  Warwick  mine,  because  worked  for  War- 
wick Furnace  at  Pottstown.  It  is  however  5  miles  W.  N.  W. 
of  the  Warwick  mine  in  Chester  county.  It  is  situated  at 
the  head  of  theConestoga  valley,  where  the  Lancaster  lime- 
stone narrows  to  a  point  between  the  Trias  belt  and  the 
Chiques  quartzite  lying  on  the  Welsh  mountain  gneiss.  An 
open  quarry  of  5  acres  (in  1857)  has  a  N.  wall  of  (20°,  N. 
30°  W.  dipping)  magnesian  limestone  beds  under  which  are 
the  ore-bearing  Primal  slates  turned  into  a  limonite  and 
magnetic  ore  mass  by  a  trap  dyke  on  the  southern  side  of 
the  mine  (next  the  quartzite).  The  purest  and  richest  ore 
is  next  the  trap.  Copper  sulphide,  carbonate  and  silicate 
occur  in  the  ore  (as  at  Cornwall).  The  total  output  has 

*  Close  by  is»  the  Knauertown  (or  P'rench  Creek,  or  Elizabeth)  Copper 
mine,  in  gneiss,  but  with  a  granite  S.  wall,  dip  steep  to  N.  ;  width  of  lode 
45' ;  shaft  140'  deep  vertical,  and  45'  more  on  the  dip,  to  a  star  of  short  gang- 
ways in  three  directions  ;  abandoned  May,  1854.  Massive  dyke  of  trap  just 
south  of  the  mine,  at  the  north  edge  of  the  tongue  of  the  Trias.  Gangue 
largely  calc  spar,  through  which  are  scattered  crystals  of  magnetite,  pyrite 
and  chalcopyrite.  the  last  most  abundant  at  the  N.  wall.  (Rogers,  in  C3, 
p.  243. 

t  E.  B.  Harden,  1882,  in  C4,  p.  244. 

}See  Mrs.  James'  Mem.  of  T.  Potts,  Jr.  ;  Swank's  Statistics  for  10th  cen- 
sus ;  Lesley's  Iron  Man.  Guide  1859,  p.  561 ;  d'Invillier's  Report,  D3,  p.  226. 
Rogers'  Geol.  Pa.  1858,  Vol.  1,  p.  182.  An.  Rt.  Geol.  Survey  Pa.  1810. 


268  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

been  very  great,  as  the  mine  has  been  wrought  ever  since 
the  Revolutionary  War ;  in  1853  it  was  7,000  tons  ;  average 
for  the  year  1850  to  1854  (during  which  a  futile  attempt  to 
mine  it  for  copper  also)  10,000  tons.* 

The  Dotterer  red  hematite  mine  in  Earl  township  is  a 
remarkable  instance  of  the  uncertain  relationships  of  some 
of  our  ores.  It  is  the  only  mine  in  Berks  county  showing 
plainly,  i.  e.,  in  workable  mass,  the  two  varieties  of  specu- 
lar iron  ore,  viz :  (1)  massive,  crystalline,  steel  gray,  weath- 
ering reddish  ;  and  (2)  earthy,  uncrystalline,  blood-red  to 
brown  ;  evidently  grades  in  the  change  from  hydrous  limo- 
nite to  unhydrous  specular,  with  or  without  the  produc- 
tion of  magnetite. 

The  bed,  44'  thick,  stands  nearly  vertical  (80°)  between 
a  foot  wall  of  conglomerate  and  a  hanging  wall  of  chlorite 
slate  ;  and  is  itself  merely  a  deep  red  ore-charged  portion 
of  this  chlorite  slate  formation.  The  conglomerate  made 
up  of  pebbles  of  gneiss  and  quartzite,  runs  along  the  east 
flank  of  Saw  Mill  Hill  (near  the  summit  of  which  the  mine 
shaft  is  sunk)  while  the  crest  and  west  flank  are  made  by 
the  primal  quartzite.  The  ore,  therefore,  seems  to  belong 
to  the  lower  primal  slate  formation,  overturned  slightly 
beyond  the  vertical. f — Some  excellent  red  hematite  has 

*  The  geological  position  of  this  body  of  ore  is  unmistakably  the  same  with 
the  whole  range  of  Primal  limonite  deposits  of  the  south  edge  of' the  Great 
Valley  ;  and  yet  the  ore  is  classed  (and  very  properly )  withthe  magnetic  iron 
ores.  There  is  less  reason,  therefore,  to  doubt  that  the  Warwick  and  Pick- 
ering valley  ores  of  Chester  county  belong  to  the  same  Primal  hydromica 
(damourite)  slates.  The  magnetite,  the  copper  and  the  trap  seem  to  go 
always  together,  in  the  case  of  those  limonite  deposits  which  have  been 
wholly  or  partially  changed  into  magnetic  ores  ;  whether  as,  in  this  instance 
of  the  Jones  mine,  the  slates  are  at  the  bottom  of  the  No.  II  limestones,  or  in 
the  case  of  the  Cornwall  mine  where  the  slates  seem  certainly  to  be  at  the 
top  of  them.  Where  there  is  no  trap  there  is  no  magnetic  ore,  and  no  copper. 

f  See  description,  vertical  section  and  mine  plane  by  Mr.  D'Invilliers  in 
Report  D3,  Vol.  1,  354,  etc.  In  the  extreme  north  of  New  York  State  red 
hematite  is  mined  beneath  Potsdam  and  over  slates.  In  Berks,  Pa.,  the 
Lock  Ridge  magnetic  range  (p.  253)  seems  to  occupy  this  position.  In 
Virginia  the  red  hematites  occur  in  the  lower,  and  the  limonites  in  the  upper 
primal  slates;  ores  however  being  also  mined  in  the  intervening  sand- 
stones and  conglomerates.  (  A.  S.  McCreath's  Mineral  Wealth  of  Va.,  p.  9.) 
In  New  Jersey  the  red  hematite  comes  in  between  marbles  and  gneisses ; 


MAGNETIC   MINES    IN   BERKS   CO.  269 

been  won  from  Kaufman  &  Spangler"*  s  old  mine  in  Furnace 
Hill,  Earl  township,  long  abandoned,  apparently  in  quartz- 
ite.* — Red  hematite  was  got  close  to  limonite  in  Brum- 
bach's  ore  holes  in  quartzite  on  the  hill  1  m.  W.  of  Green 
Hill  tavern  near  the  old  Rockland  forges. f 

For  the  magnetic  iron  ore  mines  of  Berks  county  I  must 
refer  the  reader  to  Mr.  D'Invillier's  Report  D3,  Chapter 
VIII,  pp.  237  to  351,  where  he  will  find  described  in  detail 
the  interstratified  magnetites  of  the  Mesozoic  conglomerate  ; 
the  Rittenhouse  Gap  district,  Thomas  I.  Co.  mines,  Tunnel 
mine;  Gap  Mine  range,  Moll  &  Geary.  Conrad  slope, 
Ginkinger,  Weller,  Wetzel,  Miller,  Dunkle,  Gardner  sta- 
tion, Marstellar,  new  and  old  Mickley,  Finlay,  Fegley  (S. 
Boyer  &Co.),  Frederick,  Fritch,  Tutham  mines  ;  the  Rock- 
land  township  mines.  Beitler ;  Ruscombmanor  mines, 
Clymer,  Tunnel,  Schittler  ;  Oley  township,  Tulley  ;  Alsace 
township,  Reading  old  banks  ;  Hartford  township,  Sies- 
holtzville,  Bittenbender,  Gehman,  Shimersville ;  Washing- 
ton township,  Landis,  Barto,  Stouffer,  Gilbert,  Gilberg ; 
Pike  township  ;  Earl  township,  Phoanixville  and  Warwick 
mines  ;  the  Gabel  mine  ;  the  Fritz  Island  mine  ;  the  Rau- 
denbush  ;  the  Wheattield  ; — and  the  Ruth. 

but  in  Berks  county  no  such  alliance  is  known.  The  only  instance  of 
micaceous  red  hematite  known  in  Berks  is  an  unworkable  vein  on  Fritz 
Island  below  Reading.  The  Dotterer  mine  is 2  m.  due  W.  from  Hill  church  ; 
had  3  shafts  66',  61',  and  50'  deep,  with  cross  cuts,  etc.,  described  in  D3,  p. 
356.  The  foot  wall  for  at  least  75'  along  strike  is  everywhere  a  clay  slate, 
rich  in  alumina,  poor  in  iron,  carrying  5  per  cent  titanic  acid ;  used  at 
Phcenixville,  at  Pottstown,  and  (1882)  at  Norway  (old  Lawrence)  furnace 
to  mix  with  more  refractory  magnetites,  but  no  limonite.  (See  statistics  of 
charge,  analyses,  etc.,  on  pp.  356  to  359.) 

*  The  ore  was  hard,  compact,  lustrous,  what  there  was  of  it  Here  occurred 
also  magnesite  (carbonate  of  magnesia).  See  Genth's  Report  B,  p.  157. 

fThe  hill  is  riddled  with  trial  shafts  which  yield  very  little  of  this  rich 
and  desirable  ore. 


270  GEOLOGICAL  SURVEY    OF   PENNSYLVANIA. 


CHAPTER  XXII. 

On  the  Great  Valley. 

The  earliest  settlers  of  Pennsylvania  soon  learned  to  rec- 
ognize the  superior  fertility  of  limestone  land. 

While  one  stream  of  immigration  from  Philadelphia  fol- 
lowed the  line  of  the  Chester  county  valley,  occupied  the 
plain  of  Lancaster,  and  spread  itself  along  the  Lebanon, 
Harrisburg,  Carlisle  and  Chambersburg  belt,  two  other 
streams  ascended  the  Schuylkill,  Delaware  and  Lehigh 
rivers  to  take  possession  of  the  Easton,  Bethlehem,  Allen- 
town  and  Rending  portions  of  the  same  belt. 

The  distinction  was  then  made  in  the  markets  of  Phila- 
delphia between  the  wagons  which  came  from  the  Little 
valley,  and  those  which  came  from  the  Great  valley.  The 
Little  (Chester,  Downingtown)  valley  was  near  at  hand; 
the  Great  (Lehigh,  Berks  county,  Lebanon,  Cumberland) 
valley  was  far  away  in  the  interior  of  the  State,  among  the 
Indians  and  the  mountains. 

The  Lancaster  plain  was  popularly  called  the  Conestoga 
valley,  of  which  the  Pequea  valley  was  a  subdivision,  and 
was  known  to  extend  beyond  the  Susquehanna  river  as  the 
Codorus  valley  of  York  county. 

These  were  the  gardens  of  the  new  State,  which  made  the 
market  of  Philadelphia  the  finest  in  the  world. 

The  Great  valley  of  Pennsylvania  derives  its  name  not 
only  for  its  unusual  width  but  for  its  extraordinary  length. 
Whereas  the  Little  valley  \$  confined  to  two  counties,  Ches- 
ter and  Montgomery,  is  no  where  more  than  three  miles  wide, 
and  is  baunded  by  ranges  of  land  scarcely  300  feet  higher 
than  its  floor — the  Great  valley  has  an  uninterrupted  course 
of  1000  miles,  from  Canada  to  Alabama.  In  Pennsylvania 
it  has  a  course  of  150  miles,  is  in  some  places  20  miles  wide, 
and  is  bounded  by  mountain  ranges  1000  feet  high. 


THE   GREAT   VALLEY. 


271 


Levels  above  tide  of  the  water  ways. 

It  is  transversely  crossed  by  all  the  principal  rivers  of  the 
middle  Atlantic  seaboard — by  the  Hudson  at  Newburgh, 
by  the  Delaware  at  Easton,  by  the  Schnylkill  at  Reading, 
by  the  Susquehanna  at  Harrisburg,  by  the  Potomac  at 
Harper's  Ferry,  by  the  James  in  middle  Virginia,  and  in 
southern  Virginia  by  the  New  river,  which  flows  the  other 
way,  westward,  under  the  name  of  the  Great  Kenawha,  into 
the  Ohio. 

These  rivers  enter  the  valley  by  gaps  in  the  North  mount- 
ain, and  leave  it  by  gaps  through  the  South  mountain  ;  and 
while  crossing  it  are  bordered  by  hills  two  or  three  hun- 
dred feet  high;  or  in  other  words,  the  water  channels  of  the 
rivers  are  sunk  that  much  beneath  the  average  level  of  the 
general  floor  of  the  valley,  showing  a  remarkable  uniformity 
in  the  structure  of  the  valley  for  several  hundred  miles. 
It  is  only  towards  its  far  northern  end  that  it  is  cut  through 
down  to  tide  level,  by  the  Hudson  river. 

The  Delaware  enters  the  valley  at  the  Water  Gap  at  300' 
A.  T.  and  leaves  it  at  Easton  at  150'  A.  T. 

The  LeJiigh  enters  it  at  about  370'  A.  T.  and  then  flows 
sidewise  eastward  into  the  Delaware  at  Easton. 

The  ScJmylkill  enters  it  at  Port  Clinton  at  400'  A.  T.  and 
leaves  it  at  Reading  at  180'  A.  T. 

The  Swatara  enters  it  at  about  450'  A.  T.  and  then  flows 
sidewise  westward  into  the  Susquehanna. 

The  SusqueJianna  .enters  it  four  miles  above  Harrisburg 
at  about  300'  A.  T.  and  leaves  it  at  Columbia  about  250'  A.  T. 

The  Potomac  enters  it  at  about  300'  A.  T.  and  leaves  it  at 
Harper's  Ferry  at  about  250'  A,  T. 

To  put  this  in  tabular  form  :  * 


A 

c 

I 

J 

. 

| 

f( 

9 

oj 

X 

ja' 

C8 

a 

a 

& 

>> 

&0 

£ 

1 

s 

GO 

02 

3 

a 
i 

3 

• 
1 

North  Mountain,  

300' 

300' 

450' 

400' 

370' 

300'  A.  T. 

South  Mountain,   

250' 

250' 

180' 

150'  A.  T. 

*  For  all  these  levels  see  Report  on  Levels,  N,  18?a 


272 


GEOLOGICAL  SURVEY   OF   PENNSYLVANIA. 


It  is  plain  to  see  that  the  three  great  rivers  which  drain 
a  large  portion  of  four  states,  Virginia,  Maryland,  Penn- 
sylvania and  New  York,  have  cut  the  deepest  channels ; 
and  that  all  three  enter  the  Great  Valley  at  exactly  the 
same  level,  300'  A.T.  ;  while  the  smaller  intermediate  rivers, 
Lehigh,  Schuylkill  and  Swatara,  have  cut  down  only  to 
370',  400'  and  450'. 

From  the  Delaware  to  the  Susquehanna  water  gaps  in  the 
North  mountain  the  distance  (in  a  straight  line)  is  just  100 
miles. 

From  the  Susquehanna  to  the  Potomac  water  gaps  (in  a 
straight  line)  is  75  (but  by  the  curve  of  the  North  mountain 
85)  miles. 

From  the  Potomac  to  the  James  river  water  gaps,  the 
valley  of  Virginia  is  straight  for  160  miles,  and  instead  of 
being  crossed  by  intermediate  rivers,  is  drained  lengthwise, 
northward,  into  the  Potomac,  by  the  Shenandoah  river  120 
miles  long. 

The  various  sections  of  the  Great  Valley  are  drained  by 
large  streams  flowing  from  divides  both  ways  to  the  trans- 
verse river  channels  ;  thus  :  (1)  The  Little  Lehigh  eastward 
into  the  Lehigh  and  so  into  the  Delaware ;  (2)  Antilauna 
(Maiden)  creek  westward  into  the  Schuylkill ;  (3)  Tulpe- 
hocken  creek  eastward  into  the  Schuylkill ;  (4)  Swatara 
creek  westward  into  the  Susquehanna  ;  (5)  Connedogwinit 
and  Yellow  Breeches  creek  eastward  into  the  Susquehanna  ; 
Conecocheague  creek  westward  into  the  Potomac. 


ylk 
ek 


Divi 
Li 


250' 


783' 


310' 


501' 


200' 


270' 


485' 


230' 


150' 


THE  GREAT  VALLEY.  273 

The  divides  at  the  heads  of  these  lateral  or  in-valley 
streams  represent  the  general  level  of  the  whole  floor  of  the 
valley  across  the  state  ;  and  the  levels  of  these  divides  are 
indicated  by  the  summit  stations  of  the  various  railroads 
which,  together,  make  a  continuous  line  of  traffic  from  end 
to  end.  See  table  at  the  foot  of  last  page. 

By  this  showing  the  floor  of  the  Great  Valley  is  lower 
between  the  Delaware  and  Susquehanna,  than  between  the 
Susquehanna  and  Potomac.  But  it  must  be  remembered 
that  railroads  follow  depressions,  and  seek  the  lowest  place 
on  a  divide  ;  and  that  from  Harrisburg  to  Newville  (30£ 
miles)  the  Cumberland  Valley  railroad  grade  reads :  322', 
357',  436',  427',  458',  477'  (at  Carlisle)  and  533',  mostly  on  a 
pretty  level  limestone  plain.  In  the  next  eleven  miles  it 
rises  to  654',  and  suddenly  then  to  the  "summit"  783'; 
falling  again  at  Chambersburg  to  618'  and  at  Greencsstle  to 
585'.  So  that  in  reality  we  may  feel  safe  in  assuming  a  gen- 
eral level  of  the  floor  of  the  valley  across  the  whole  state, 
as  traversed  by  the  lines  of  railroad,  at  about  500'  A.  T.* 

*  A  line  of  levels  carried  along  railway  lines  from  Sandy  Hook  via  Hagers- 
town,  Md.,  Gratton,  Va.,  Athens,  O.,  Mitchell,  lad.,  to  St.  Louis  (published 
in  Coast  Survey  Report  for  1882,  page  521-f,  with  a  map  of  the  route,  page 
557),  fortunately  for  our  present  purpose,  follows  the  Great  Valley  from 
Easton,  through  Allentown,  Reading,  Lebanon,  Harrisburg,  Carlisle  and 
Chambersburg  to  Hagerstown,  and  then  ascends  the  valley  of  the  Potomac 
on  its  way  west 

Easton.  (No.  XIX)  Cut  on  one  of  the  central  piers  of  the  RR.  bridge 
across  the  Lehigh  river,  214'  above  mean  sea  level. 

Easton.     (XX)  Cut  W.  corner  of  jail,  on  foundation  stone,  357.5'. 

Easton.     (U)  Sill  of  blind  window,  E.  side  of  court  house,  363.5'. 

AHentown.  (I)  Cut  on  sill  of  basement  window  S.  side  of  front  entrance 
of  jail,  321'. 

One  and  a  half  miles  W.  of  Allentown.  (XXI)  Cut  on  N.  W.  corner  RR. 
bridge  over  wagon  road,  295  5'. 

One-half  m.  W.  of  Macungie  station.  (XXII)  Cut  on  top  stone,  N.  side 
RR.  bridge  over  small  run,  383.5'. 

Reading.  (J)  Cut  on  coping  stone,  E.  abutment  of  N.  E.  RR.  bridge  at 
RR.  depot,  264'. 

One-quarter  m.  E.  of  Shamrock  station.  (XXIII)  Cut  on  N.  E.  corner 
RR.  bridge,  424.5'. 

One-eighth  m.  E.  of  Robesonia  station.  (XXIV)  Cut  on  pier  of  small 
bridge,  432.5'. 

18 


274  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

But  the  lines  of  railroad  connect  the  principal  towns  of 
the  valley  ;  and  these  have  all  been  built  on  the  most  fertile 
and  smoothest'part  of  the  valley  floor,  viz  :  its  southern  belt 
composed  of  limestone  soil ;  and  it  is  to  this  belt  alone  that 
the  above  average  of  500'  A.  T.  applies  ;  its  northern  belt  is 
rougher  and  higher. 

The  two  belts. 

The  Great  Valley  is  divided  geologically  lengthwise,  from 
end  to  end,  into  two  belts  of  country  ;  one,  next  the  North 
mountain,  a  slate  belt;  the  other,  next  the  South  mountain, 
a  limestone  belt.  The  line  of  separation  in  some  places  runs 
for  miles  remarkably  straight ;  in  other  places  it  is  remarka- 
bly crooked  ;  but  along  the  whole  course  it  may  be  called  the 
middle  line  of  the  valley  ;  the  slate  region  being  to  the  north 
and  west  of  it ;  although  occasional  streaks  of  limestone  ap- 
pear in  the  slate  belt,  and  occasional  patches  of  slate  in  the 
limestone  belt ;  but  the  relative  proportions  in  width  vary, 
the  slate  belt  being  nearly  every  where  the  wider  of  the  two, 
and  in  parts  of  the  valley  twice  or  even  three  times  as  wide 
as  the  limestone  belt.  In  Cumberland  county,  however, 
the  limestone  belt  is  a  little  wider  than  the  slate  belt. 

One  and  a  halfm.  W.  of  Womelsdorf  station.  (XXV)  Cut  at  E.  end  of 
base  of  N.  wall  of  overhead  bridge  RR.,  483.5'. 

Lebanon.  St.  Mary's  Catholic  church.  (XXVI)  Cut  on  S.  side  of  south- 
ernmost front  entrance  ;  centre  of  cross,  on  white  marble  block,  474.5'. 

Lebanon.  (K)  Bottom  of  square  hole  in  top  of  marble  post  in  ground  oi 
Mr.  P.  L.  Weiner,  S.  E.  corner  Eighth  and  Chestnut  streets,  465.5'. 

One  and  a  quarter  m.  W.  of  Annville.  (XXVII)  S.  W.  corner  RR.  bridge 
over  Joe  Crider's  dam,  405'. 

Swatara  bridge  (RR.)  (XXVIII)  Cut  on  stone  parapet  between  Beaver 
and  Hummelstown  station,  367.5'. 

Harrisburg.  (XXIX)  Centre  of  top  surface  of  monument  in  capitol 
grounds,  marking  astron.  stat.  coast  survey,  356.5'. 

(L)  Cut  at  base  of  pillar  at  S.  E.  corner  capital  building,  367.5'. 

Carlisle.     (M)  Cut  on  base  of  column  at  W.  side  of  jail  entrance,  472.5'. 

Shippensburg.  (XXX)  Cut  on  water  table  of  house  and  store  of  W.  C. 
J.  Reddig,  N.  W.  Corner  Main  and  Railroad  streets,  654'. 

Chambersburg.  (N)  Cut  on  pedestal  at  base  ofN.  pillar  of  court  house 
front,  620.5'. 

Greencastle.  (XXXI)  Center  of  cross  cut  in  stone  in  front  wall  of  RR. 
depot,  7"  above  sidewalk,  S.  of  entrance,  588  5  . 

Hagerstown.  (A)  Cut  on  water  table  of  court  house,  corner  Washington 
and  Jonathan  streets,  on  Jonathan  street  side,  552.5'  =  168.3402  meters, 


THE   GREAT   VALLEY   BELTS.  275 

The  Slate  belt  has  an  average  general  level  about  two  hun- 
dred feet  higher  than  the  limestone,  say  700'  A.  T.  This  is 
strongly  marked  all  the  way  from  the  Delaware  river  at 
Belvedere,  to  the  Schnylkill  river  at  Leesport,  by  a  steep 
hill-slope  down  from  the  higher  slate  floor  of  the  valley  to 
its  lower  limestone  floor;  and  this  step  in  the  surface  is 
made  more  remarkable  by  narrow  openings  or  ravines  from 
which  issue  numerous  small  water  courses  heading  in  the 
recesses  of  the  slate  land,  and  at  the  foot  of  the  North 
mountain. 

This  elevated  terrace-like  edge  of  the  slate  belt  contin- 
ues, although  in  less  regular  style,  through  Berks  into 
Lebanon  county  ;  can  be  recognized  in  Dauphin  and  Cum- 
berland counties  ;  but  gradually  becomes  less  conspicuous 
in  Franklin  county.  There  is  no  mistaking,  however,  the 
greater  relative  height  of  the  slate  belt  everywhere  along 
the  Great  valley. 

The  distinction  is  emphasized  moreover  in  all  cases  where 
limestone  coves  invade  the  slate  belt,  and  where  slate  ridges 
traverse  the  limestone  belt.  It  is  evident  to  the  most  in- 
different spectator  that  the  surface  of  the  limestone  land 
lies  naturally  lower  than  that  of  the  slate  land,*  but  a 
clear  exhibition  is  made  of  it  by  the  contour-line  maps  of 
Lehigh  and  Northampton  counties  published  with  Reports 
of  Progress  D,  Ds  and  Ds.  These  maps  show  the  relative 
levels  of  the  whole  limestone  belt  of  the  valley,  of  the  edge 
of  the  slate  belt,  and  of  the  slopes  of  the  South  Mountains, 
all  the  way  from  the  Delaware  to  the  Schuylkill  rivers,  f 

No  contour -line  surveys  of  the  Slate  belt  have  been  made 
anywhere  along  the  valley  ;  and  until  such  surveys  have 
been  made  and  a  continuous  contour- line  map  of  it  has  been 

*  The  reason  for  it  will  be  given  further  on,  in  connection  with  the  under- 
ground cavernous  condition  of  the  limestone  belt. 

t  It  is  evidently  desirable  that  the  Legislature  should  provide  means  for 
continuing  this  topographial  survey  westward  across  the  Susquehanna  river 
to  the  Maryland  line. 

In  Franklin  and  Cumberland  counties  the  South  Mountains  have  been 
elaborately  surveyed  in  the  same  manner,  and  down  their  western  slopes  to 
the  south  border  of  the  limestone  belt ;  but  the  means  of  the  survey  were 
to  olimited  to  bear  the  expense  of  carrying  the  work  across  the  limestone 
land  to  the  edge  of  the  slate  land. 


276 


GEOLOGICAL   SURVEY    OF   PENNSYLVANIA. 


C/i.XXII,p/ate/T 


Conedoguincl  Creek  in  Cumberland  Co.  fa. 


THE   GKEAT   VALLEY   BELTS. 


277 


§£  I.&S'S 


278  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

executed,  no  entirely  accurate  knowledge  of  its  geological 
structure  can  be  obtained.  We  know,  however,  that  it  is 
everywhere  very  much  crumpled  into  narrow  folds ;  and 
that  some  of  these  folds  are  so  sharp  that  the  limestone  for- 
mation everywhere  underlying  it  comes  occasionally  to  the 
surface. 

The  north  edge  of  the  Slate  belt  is  high  up  on  the  slope 
of  the  North  mountain ;  in  fact  the  outcrops  of  the  top 
layers  of  the  formation  run  only  one  or  two  hundred  feet 
beneath  the  crest  of  the  mountain. 

Synclinal  mountains  of  IV  in  III. 

The  upper  part  of  the  Slate  formation  is  coarser  or  more 
massive  than  the  lower  part,  and  in  some  places  contain 
pebbles  in  such  abundance  as  to  become  conglomerate  rock. 
Therefore,  as  in  some  places  along  the  south  edge  of  the 
slate  belt  the  underlying  limestone  comes  to  the  surface 
along  the  middle  line  of  an  uncommonly  sharp  and  strong 
up/old — so  in  some  places  along  the  north  edge  of  the  slate 
belt  the  upper  and  coarser  slates  have  been  preserved  along 
the  middle  line  of  an  uncommonly -sharp  and  deep  down- 
fold. 

In  two  notable  cases  even  the  Medina  sandstone  No.  IV 
has  been  thus  preserved  ;  and  this  is  the  explanation  of 
Hole  mountain  in  Lebanon  county,  and  ParneWs  Knob 
mountain  in  Franklin  county — both  of  them  standing  out 
in  front  of  the  North  mountain.  (Plate,  page  285.) 

Hole  mountain  in  Lebanon  county  is  a  ridge  five  miles 
long  ending  at  the  Swatara  river.  Its  top  is  a  V-shaped 
pinched  stripe  of  the  sandstone  No.  IV,  held  in  a  vice  of 
upper  slates.  Along  the  banks  of  the  Swatara  the  slates 
can  be  seen  going  down  in  front  of  it  and  coming  up  behind 
it,  and  then  going  down  again  under  the  North  mountain. 

ParneW  s  mountain,  in  Franklin  county,  is  of  precisely 
the  same  character,  but  longer,  and  produced  by  a  deeper 
down-fold  (synclinal)  of  the  slate  belt.  It  is  10  miles  long 
and  entirely  cut  off  from  the  North  mountain  behind  it  by 
the  narrow  straight  upfold  (anticlinal)  of  Bear  valley.  The 
down-fold  is  so  deep  that  a  regular  canoe  of  the  sandstone 


THE   GREAT   VALLEY   BELTS.  279 

No.  IV  has  been  preserved,  its  two  crests  being  separated 
by  a  middlegroove  in  which  lie  some  of  the  lowest  soft  layers 
of  the  Clinton  red  shale  formation  No.  V. 

In  studying  Hole  mountain  we  make  a  first  step  towards 
understanding  the  geology  of  all  Middle  Pennsylvania  ;  in 
studying  ParneTC  s  mountain  we  make  a  second  step  ;  and 
if  we  consider  Jordan's  Knob  behind  it,  we  take  the  third 
step.  For  the  North  mountain  here  (at  London)  doubles 
back  upon  itself  (see  page  plate)  and  after  zigzaging  around 
Horse  valley,  Amberson's  valley  and  Path  valley,  comes 
back  to  Loudon  and  runs  on,  as  if  nothing  had  happened 
to  divert  it  from  its  course,  into  Maryland.  But  all  these 
zigzags  represent  high  upfolds  and  deep  downfolds  in  the 
slate  formation  No.  Ill  which  underlies  the  mountain  every- 
where ;  and  not  only  in  the  slate  formation  No.  Ill,  but 
in  the  limestone  formation  No.  II  which  lies  still  deeper 
everywhere  under  the  slate  ;  for  along  the  middle  of  Am- 
ber son' s  valley  and  Path  valley  the  underlying  limestone 
has  been  brought  up  and  bared  at  the  surface  ;  while  the 
steep,  dipping  slates  are  confined  to  the  side  hills  and  to 
the  steep  mountain  slopes.* 

Anticlinal  bells  of  limestone  in  the  slate. 

The  great  upfold  (anticlinal)  of  Path  valley  runs  on  from 
Loudon  southward  bringing  to  the  surface  in  front  of  Cove 
mountain  a  narrow  belt  of  limestone. 

The  upfold  of  Bear  valley  runs  on  also,  by  Bridgeport, 
Mercersburg  and  Simpstown,  and  brings  to  the  surface 
another  long  narrow  belt  of  limestone.  Between  these 
two  parallel  limestone  strips  runs  a  strip  of  slate,  preserved 
in  the  downfold  (synclinal)  of  Jordan's  Knob.  The 
Loudon  and  the  Mercersburg  strips  of  limestone  termi- 
nate in  two  coves  at  the  Maryland  line,  the  Punchbowl 
(or  Corner),  and  Blair's  valley;  and  these  two  coves  lie 
between  Cove  mountain  and  two  mountain  spurs  in  Mary- 
land (Two  Top  mountain  and  Casey's  knob)  which  ex- 
actly correspond  to  Jordan's  knob  and  Parnell's  knob 

*  Along  the  north  side  of  Path  valley  runs  a  great  fault,  so  that  the  under- 
lying limestone  has  slipped,  up  against  the  upper  slates  on  the  mountainside. 


280  OEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

Ch.XXH,  plate  3. 


THE   GREAT  VALLEY   BELTS. 


281 


Cross  section  of  the  Great  Valley  from  near 
Cowan's  Gap  south  through  Scotland  to  the 
South  Mountain  in  Franklin  County,  ?a. 


282  GEOLOGICAL   SURVEY    OF  PENNSYLVANIA. 

towards  which  they  look,  the  distance  being  about  14  miles. 
Blair's  valley  is  the  easternmost  of  the  two  coves,  and  corres- 
ponds in  all  respects  to  Bear  valley  between  the  Jordan 
and  Parnell's  knobs. 

The  geology  of  this  part  of  Fayette  county  is  beautifully 
simple,  symmetrical  and  instructive.  It  is  rendered  still 
more  instructive  by  the  following  particular  : 

A  third  upfold  (anticlinal)  runs  in  front  of  Parnell's 
mountain,  and  brings  to  the  surface  in  the  slate  belt  the 
underlying  limestone  in  a  third  long  narrow  slip,  which 
starts  at  a  point  at  Strasburg,  and  is  crossed  by  the  Cham- 
bersburg  pike  just  west  of  St.  Thomas,  where  it  is  1%  mile 
wide.  After  passing  St.  Thomas  southward  this  strip  of 
limestone  becomes  nearly  5  miles  wide  at  the  Greencastle- 
Mercersburg  pike,  and  so  passes  on  into  Maryland.  The 
slate  belt,  which  is  seven  miles  wide  at  Newville  in  Cumber- 
land county,  6  miles  wide  at  Chambersburg  in  Fayette 
county,  is  thus  narrowed  to  3  miles  at  Welsh  run  and  the 
Maryland  line ;  the  main  limestone  belt  13  miles  wide  bor- 
dering it  on  the  east,  and  the  Welsh  run  limestone  belt  4 
to  5  miles  wide  bordering  it  on  the  west. 

This  widening  of  the  Welsh  Run  limestone  belt  south- 
ward from  St.  Thomas  might  have  been  produced  in  two 
ways  ;  it  was  actually  produced  in  a  third  way  exactly  con- 
sistent with  all  that  has  just  been  said.  (1)  It  might  have 
been  produced  by  a  swelling  upward  of  the  Strasburg  anti- 
clinal after  passing  south  by  St.  Thomas ;  or  (2)  it  might 
have  been  produced  by  a  flattening  out  of  its  dips  on  both 
sides ;  but  it  actually  was  produced  (3)  by  two  other  addi- 
tional anticlinals  running  alongside  of  (in  front  or  east  of) 
the  Strasburg  upfold; — one,  which  may  be  called  the  St. 
Thomas  anticlinal,  brings  up  a  strip  of  limestone  south  of 
St.  Thomas  ; — the  other,  the  Rock  Spring  anticlinal,  which 
brings  up  a  little  prong  of  limestone  3  miles  S.  of  St.  Thomas, 
and  after  crossing  the  slate  belt  obliquely  produces  the 
Rock  Spring  limestone  cove  3  miles  N.  of  Chambersburg. 

These  three  up-folds  in  the  slate  belt  of  middle  and 
northern  Franklin  combine  to  keep  the  limestone  up  to  the 
surface  along  the  Wetsh  run  belt  near  the  Maryland  line. 


THE   GREAT   VALLEY   LIMESTONE   COVES.  283 

Limestone  coves  in  the  slate  belt  edge. 

The  limestone  indentation  in  the  edge  of  the  slate  belt 
at  Rock  Springs  is  about  3  miles  deep.  (Plate,  page  285.) 

Another  similar  indentation  of  limestone  in  the  south- 
east edge  of  the  slate  belt  occurs  at  Fairview  and  Middle 
Spring  on  the  Cumberland  county  line  (page  plate).  Both 
these  indentations  point  southwest,  showing  that  the  anti- 
clinals  which  upheave  the  underlying  limestone  through 
the  slate  sink  in  that  direction. 

Another  indentation  is  shown  upon  the  map  at  Newville 
in  Cumberland  county,  but  it  points  northeast.  Newville 
is  built  in  this  little  limestone  cove  and  has  slate  hills  all 
round  it  except  to  the  west.  The  outlines  of  slate  show  a 
downfold  (synclinal)  running  just  south  of  the  village. 

Another  very  little  indentation  in  the  south  edge  of  the 
slate  belt  is  made  at  Plainfield,  4  miles  west  of  Carlisle,  and 
the  arrows  on  the  map  along  the  creek  here  show  that  the 
prong  of  slate  is  a  true  synclinal. 

Another  very  pretty  indentation  of  limestone  in  the  slate 
belt,  two  miles  long  and  pointing  (like  the  last  two)  east- 
ward, lies  back  (north)  of  Kingston,  six  miles  east  of  Car- 
lisle. Here  the  arrows  on  the  map  instead  of  explaining 
the  facts  are  very  confusing,  all  of  them  pointing  south  at 
various  angles.  The  cause  of  this  will  be  explained  here- 
after, but  it  may  as  well  be  mentioned  here  that  most  of 
these  upfolds  (anticlinals)  and  downfalls  (synclinals)  are 
not  only  squeezed  tightly  together,  but  so  bent  over  north- 
ward (as  if  by  a  pressure  from  the  South  mountains)  that 
the  strata  which  ought  to  dip  north  dip  south,  and  cannot 
therefore  be  easily  separated  from  those  which  ought  to  dip 
south.  In  other  words,  one-half  of  the  south  dipping  strata 
are  in  reality  overturned  and  lie  with  their  upper  faces 
downwards. 

Another  limestone  cove  in  Cumberland  county  runs  up 
into  the  south  edge  of  the  slate  belt  in  the  opposite  direc- 
tion (northeast)  behind  the  long  prong  of  slate  which  points 
out  half  a  mile  west  of  Kingston  along  a  deep  downfold 
(synclinal)  in  the  limestone  belt.  (Plate,  page  276.) 

No  such  interruptions  of  the  south  edge  of  the  slate  belt 


284  GEOLOGICAL   SURVEY   OF   PENNSTLVANIA. 

Ch.XXU,  plate  5~. 


Specimen  section  ofwaveA  in 
7o  tiluttrcdc 


anticlinal  Coves  of  JT,  and.  synclinal  Prangs 
cdong-tke  center  line  cfthc  ^eaJ;Yaflcy,  Cumber/and 


MOURSVILLE 


•,tt 


TOx 


FAIRVIEW 


;t^( 


-25' 


90° 


I 


,40° 


so; 


\20° 


diagonal  and 'transverse-  limes-Tone  tL'jj,).     ,. 


THE   GREAT   VALLEY   LIMESTONE   COVES.  285 


limestone  and  Slate  belts-  (M^HT)  of  the,  9reat  Yallcy. 
7o  illustrate  Chap, XXII  of  Ttnal  Report  IWf, 


T/  4'"   '       NV  »'  /^N 

*    ''  ji  Chamber s'&ury      *$    ^  ( 

»*  r&        **•     '       »X     .  .jV 


286  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

occur  in  Dauphin  and  Lebanon  counties.  In  Berks  county, 
approaching  the  Schuylkill,  they  become  very  numerous, 
but  produce  a  state  of  things  geographically  so  curious 
and  important  as  to  require  a  special  description.  East  of 
the  Schuylkill  the  edge  of  the  slate  alternately  advances 
upon  the  limestone  and  retreats  from  it  in  a  series  of  small 
irregular  curves  which  scarcely  disturb  the  straight  line  of 
the  contact;  but  there  is  a  decided  cove  at  Moselem,  and 
another  at  Kutztown,  both  pointing  west;  and  together  they 
broaden  the  limestone  belt  and  contract  the  slate  belt  a 
trifle.  At  Monterey  near  the  Lehigh  county  line,  a  cove 
points  northeast. 

In  Lehigh  Co.  limestone  coves  back  of  slate  prongs  play 
a  great  role  in  the  geography.  One  is  produced  by  an  an- 
ticlinal passing  Trexlerville  ;  another  deeper  one  lies  north 
of  it ;  a  third  and  very  large  one  is  that  of  Jordan  creek ; 
a  fourth  is  the  Ironton  cove.  All  these  point  west,  and 
have  the  effect  of  reducing  the  breadth  of  the  slate  belt  on 
the  Lehigh  river  to  one-half  of  the  breadth  it  has  on  the 
Berks-Lehigh  county  line. 

In  Northampton  county  the  many  irregularities  in  the 
face  line  of  the  slate  belt  are  all  of  the  nature  of  coves  ;  but 
in  no  case  are  they  shut  in  behind  synclinal  prongs  of  slate. 
But  on  the  other  hand  we  have  here  smajl  circuses  of  lime- 
stone completely  enclosed  in  the  slate  belt,  back  of*  its  edge, 
anticlinal  in  their  structure,  and  teaching  the  same  lesson 
as  the  coves,  viz :  that  the  limestone  formation  No.  II  passes 
down  (northward)  underneath  the  slate  formation  No.  Ill, 
and  is  here  and  there  brought  up  through  it  to  the  present 
surface  by  upfolds  or  anticlinal  waves. 

Synclinal  belts  of  III  in  II. 

Prolong  two  limestone  coves  (one  pointing  east  the  other 
pointing  west  into  the  edge  of  the  slate  belt)  until  their 
opposite  points  meet,  and  you  will  have  a  strait  of  limestone 
between  the  mainland  of  slate  and  a  long  narrow  island  of 
slate  in  front  of  it  ;  the  strait  of  limestone  being  an  anti- 
clinal or  upfold,  and  the  island  a  synclinal  or  downfold,  or 
basin. 


SYNCLINAL   BELTS   OF  III   IN   II.  287 

Such  basins  of  slate  in  the  limestone  belt  are  numerous 
enough  to  prove  that  the  slate  formation  No.  Ill  originally 
entirely  covered  the  limestone  formation  No.  II. 

In  Franklin  county  one  commences  3  miles  South  of 
Chambersburg  and  runs  4  miles,  crossing  the  South  Penn 
RR.  £  mile  from  the  Marion  junction.  The  arrows  near 
Marion  point  the  limestone  going  down  very  steeply  under 
the  east  edge  of  the  slate  strip.  This  slate  strip  is  un- 
doubtedly a  closely  folded  downfold  (synclinal). 

The  other  is  a  similar  little  strip  of  slate  half  a  mile  west 
of  Greencastle,  a  few  hundred  yards  wide,  a  mile  or  so  long, 
and  separated  from  the  edge  of  the  slate  belt  by  a  strip  of 
limestone  only  a  few  hundred  yards  wide.  An  arrow  at 
its  north  end  pointing  east  and  three  others  along  the  rail- 
road pointing  west  show  that  this  little  strip  of  slate  also 
lies  in  a  closely  folded  trough  in  the  limestone. 

Returning  now  to  the  eastern  end  of  Cumberland  county, 
the  map  shows  the  slate  belt  suddenly  widening  from  3 
miles  at  Kingston  and  Hogestown  to  5  miles  at  the  Susque- 
hanna  river.  Its  edge  makes  a  beautiful  curve  to  the  river 
at  Bridgeport  and  Harrisburg.  Part  of  this  curve  is  a  great 
fault,  of  which  more  will  be  said  hereafter,  the  limestone 
country  has  been  etevated  and  the  slate  country  depressed  ; 
so  that  the  Connedogwinet  creek,  however  often  it  tried  to 
break  through  the  wall,  was  never  able  to  do  more  than 
scoop  little  semi-circles  from  it  at  various  points  along  the 
line  ;  and  this  explains  the  remarkable  loops  of  the  creek. 

In  Dauphin  county  the  edge  of  the  slate  belt  runs  on 
east  nearly  straight  for  seven  miles  to  Beaver  station  on 
the  Lebanon  Valley  railroad,  the  railroad  between  Harris- 
burg  and  Beaver  keeping  on  the  limestone.  From  Beaver 
across  to  the  North  mountain  is  all  slate,  and  the  belt  is  8 
miles  wide  and  continues  of  that  width  into  Lebanon  county, 
its  south  edge  being  a  very  even  line  and  nearly  straight. 

But  between  Beaver  and  the  Swatara  river  towards  Hum- 
melstown  there  is  a  space  of  about  a  mile  where  the  slate 
belt  throws  a  projection  southward  over  the  limestone  ;  and 


288  GEOLOGICAL  SURVEY   OF   PENNSYLVANIA. 

this  projection  turns  west  and  forms  a  belt  of  slate  land  in 
the  heart  of  the  limestone  belt,  a  mile  or  two  wide,  extend- 
ing back  6  miles  past  Church ville  to  the  Susquehanna  at 
New  Cumberland.  The  river  flows  across  this  slate  belt  3 
miles  below  Harrisburg. 

At  New  Cumberland  (on  the  west  bank  of  the  river)  this 
slate  belt  is  scarcely  half  a  mile  wide  ;  but  it  keeps  on  west, 
in  a  trough  of  the  limestone,  8  miles,  and  ends  in  two  blunt 
prongs  one  to  the  north  and  the  other  to  the  south  of 
Shepherdstown.  Before  coming  to  an  end  it  broadens  out 
to  a  width  of  two  miles,  with  such  varieties  of  dip  as  to 
baffle  all  explanation.  Only  it  is  evident  that  this  belt  of 
slate  overlies  the  limestone,  and  runs  east  and  west  about 
12  miles,  splitting  the  limestone  belt  into  two  ;  just  as  the 
three  slate  belts  of  Southern  Franklin  county  split  up  the 
limestone  belt  into  four. 

In  Lebanon  county  the  slate  belt  is  unbroken  by  the  ap- 
pearance at  the  surface  of  any  large  appearances  of  the  un- 
derlying limestone.  Its  width  from  Lebanon  to  the  Swatara 
gap  in  the  North  mountain  is  9  miles.  Its  south  edge  is 
quite  straight  as  far  as  Lebanon  ;  there  bending  a  little  it 
runs  almost  straight  into  Berks  county.  The  Union  canal 
on  the  north  side  of  Lebanon  marks  the  contact  of  the  lime- 
stone sinking  beneath  the  slate.  The  Ime  passes  one  mile 
north  of  Myerstown. 

The  limestone  belt  is  1£  miles  wide  on  the  Dauphin-Leba- 
non county  line ;  5  miles  wide  at  Lebanon  ;  G£  miles  wide  at 
Shafferstown;  and  6  miles  wide  at  the  Lebanon-Berks  county 
line. 

No  strips  of  slate  have  been  preserved  on  the  limestone 
belt,  except  at  its  southern  edge,  where  large  tracts  of  slate 
may  be  supposed  to  overlie  the  limestone  where  everything 
is  covered  up  by  the  comparatively  recent  Mesozoic  Trias 
red  shale  formation,  to  be  described  further  on. 

The  edge  of  one  of  these  slate  tracts  extends  for  4  miles  at 
Cornwall,  and  is  visible  for  a  mile  in  width  along  the  rail- 
road to  the  mines.* 

*There  may  be  some  doubt  about  these  slates  being  No.  III.  They  may 
be  tbe  slates  beneath  the  limestone. 


SYNCLINAL   BELTS   OF   III   IN   II.  289 

Another  semi-circular  slate  tract  2£  miles  long  (E.  and 
W.)  and  1£  broad  (N.  and  S.)  appears,  at  Shaefferstown. 
The  limestone  dips  beneath  it  all  around  its  eastern,  north- 
ern and  western  sides,  there  can  be  no  doubt  about  its  being 
a  preserved  portion  of  the  slate  belt,  now  separated  from  it 
by  an  eroded  interval  of  just  5  miles.  The  south  border  of 
this  patch  is  overlapped  by  the  edge  of  the  great  Mesozoic 
(Trias)  red  shale  formation  of  Lancaster  county.  How  far 
south  the  slates  extend  under  the  red  shale  is  not  known ; 
but  no  slates  appear  on  the  limestone  in  the  Manheim, 
Ephrata  and  Conestoga  valleys  in  Lancaster  county  south  of 
the  red  shale. 

In  Berks  county  the  slate  and  limestone  belts  of  the  Great 
Valley  are  so  intermingled  that  no  general  description 
would  be  understood.*  While  the  northern  or  main  part 
of  the  slate  belt  runs  to  and  across  the  Schuylkill,  long 
prongs  and  strips  of  slate  cross  the  limestone  belt  in  the 
triangular  enlargement  of  the  Great  Valley  between- 
Womelsdorf,  Leestown  and  Reading ;  and  long  strips  of 
limestone  traverse  the  slate  belt  north  of  Womelsdorf  and 
Bernville  on  the  Union  canal. 

Southern  edge  of  No.  II. 

Having  thus  traced  the  contact  of  the  limestone  and  slate 
belts  along  the  middle  line  of  the  great  Valley  from  the 
Maryland  state  line  to  the  Schuylkill  river  in  Berks  county, 
and  pointed  out  the  streaks  of  limestone  coming  up  through 
the  slate,  and  the  prongs  and  ridges  of  slate  still  left  un- 
eroded  on  the  limestone,  in  all  four  counties,  it  will  be 
proper  to  describe  the  southern  edge  of  the  limestone  belt, 
and  show  how  essentially  different  it  is  in  Franklin  and 
Cumberland,  from  what  it  is  in  Dauphin  and  Lebanon. 

The  southern  edge  of  the  limestone  belt  in  Franklin  and 
Cumberland  counties  runs  along  the  foot  of  the  South 
mountains  to  their  eastern  termination  11  miles  west  of  the 
Susquehanna  river.  Here  it  turns  round  the  end  of  the 

*  It  can  only  be  understood  by  an  examination  of  the  colored  geological 
map  of  Berks  county,  made  to  accompany  Report  D3,  Vol.  Ill,  which  re- 
mains unpublished,  except  as  one  of  the  maps  in  the  Hand  Atlas  Report  X. 
19 


290  GEOLOGICAL    SUKVET    OF   PENNSYLVANIA. 

mountain  southward  and  is  immediately  lost  beneath  the 
Mesozoic  Trias  red  shale. 

It  is  evident  that  the  limestone  of  eastern  Cumberland 
county  and  the  limestone  of  middle  Lancaster  county  are 
connected  underneath  the  Trias  red  shale  belt  which  sepa- 
rates them  at  the  present  surface  by  a  breadth  of  more  than 
10  miles  measured  along  the  river. 

Whether  the  Cumberland  county  limestone  and  the  York 
county  limestone  are  also  connected  underneath  the  Trias 
red  shale  directly  across  a  distance  of  17  miles,  is  less  cer- 
tain. The  doubt  arises  from  the  possible  underground  con- 
nection of  the  South  mountain  rocks  beneath  Dillsburg, 
Rosstown  and  Liverpool  with  Chiques  rock  at  Columbia. 

If  such  be  the  case,  we  must  draw  the  edge  of  the  under- 
ground limestone  belt  from  Yellow  Breeches  creek  (2  miles 
north  of  Dillsburg)  to  New  Holland  at  the  bend  of  the  river, 
and  so  on  towards  Lancaster  city. 

But,  on  the  other  hand,  as  we  do  not  know  what  has 
caused  the  depression  in  which  the  Trias  red  shale  was  de- 
posited, we  cannot  tell  how  deep  it  may  be  ;  consequently, 
we  cannot  tell  whether  or  not  the  limestone  in  York  county 
covers  the  South  mountain  rocks  under  the  Trias  red  shale. 

The  main  point  is  that,  when  the  South  mountains  come 
to  an  end,  the  limestone  belt  becomes  covered  with  Trias 
red  shale,  the  north  edge  of  which  is  of  course  the  south 
edge  of  the  surface  limestone  belt  in  eastern  Cumberland, 
across  Dauphin  and  nearly  across  Lebanon  county.  Not 
until  we  reach  the  eastern  corner  of  Lebanon  does  the  south- 
ern edge  of  the  surface  limestone  belt  rest  again  against 
South  mountain  rocks. 

Here  a  small  isolated  mountain  mass  called  South  mount- 
ain in  Lebanon  county  and  Mulbaugh s  Jiill  in  Berks 
county,  separates  the  limestone  belt  to  the  north  of  it,  from 
the  red  shale  belt  to  the  south  of  it  in  Lancaster  and  Ches- 
ter counties. 

East  of  Mulbaugh's  hill  the  red  shale  laps  around  and 
again  covers  the  south  edge  of  the  limestone  as  far  as  to 
the  Schuylkill  river  below  Reading. 

East  of  the  Schuylkill  river  the  South  mountain  gneisses 


THE   GREAT   VALLEY.  291 

rise  in  the  range  of  highlands,  with  the  great  valley  of  lime- 
stone at  its  north  foot,  and  so  continues  through  New 
Jersey  and  New  York  into  New  England. 

Mulbaugh 's  hill  at  the  corner  of  Lebanon,  Berks  and 
Lancaster  counties  is  therefore  an  isolated  piece  of  the 
highlands  about  2  miles  broad  and  10  miles  long,  surrounded 
on  the  north  by  limestone  and  on  the  south  by  red  shale  ; 
but  underground  no  doubt  entirely  surrounded  by  lime- 
stone ;  for  the  limestone  is  seen  going  down  under  the  red 
shale  at  both  ends  of  it ;  and  there  is  every  reason  to  believe 
that  the  Trias  belt  south  of  it,  which  is  not  more  than  6 
miles  broad  at  the  west  and  10  at  the  east,  occupies  a  buried 
limestone  valley  of  unknown  depth. 

We  have  then  in  Cumberland,  Dauphin,  Lebanon  and 
Berks  counties  an  extraordinary  phenomenon,  which  has  a 
most  important  bearing  upon  the  river  drainage  of  the  whole 
Atlantic  coast.  The  great  range  of  the  South  mountains 
which  otherwise  extends  continuously  for  many  hundred 
miles,  from  its  southern  end  in  Georgia  to  its  northern  end 
in  New  England,  is  here  broken  by  a  gap  60  miles  wide, 
I.  e.  from  Dillsburg  in  York  county  to  Reading  in  Berks 
county.  A  great  gateway  through  which  the  greatest  river 
of  the  coast  (the  Susquehanna)  drains  the  back  country  into 
the  greatest  bay  of  the  coast  (the  Chesapeake) ;  and  the 
breadth  and  depth  of  the  bay  correspond  to  the  area  and 
volume  of  the  river,  which  has  been  filling  it  during  all  the 
ages  since  the  Coal.  And  in  this  gateway  stands  a  pillar 
(Mulbaugh  s  hill)  to  mark  the  continuance  of  the  range  un- 
derground. 

Relation  of  the  South  Mountain,  uplift  to  No.  II. 

Had  it  not  been  for  this  remarkable  break  in  the  South 
mountain-Blue  Ridge-Highlands  range  of  the  Atlantic  sea- 
board region  of  the  United  States,  it  might  have  been  sup- 
posed that  the  limestone  formation  No.  II  was  deposited  in 
a  sea,  the  southeastern  shore  of  which  lay  at  the  north- 
western foot  of  the  South  mountain  range,  then  in  existence. 
But  the  South  mountain  range  was  not  then  in  existence. 


292  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA  . 

The  sea  extended  to  that  part  of  the  surface  of  the  globe 
now  covered  by  the  Atlantic  ocean. 

This  fact  is  made  known  in  several  ways : — (1)  By  the 
great  thickness  of  the  formation  at  the  foot  of  the  mount- 
ain range ;  (2)  by  the  existence  of  faults  along  the  foot  of 
the  mountain  range  ;  and  of  course  faults  presuppose  the 
spread  of  the  formation  southeast  of  the  faults  ;  (3)  by  the 
appearance  of  the  limestone  formation  in  valleys  between 
the  parallel  ridges  of  the  mountain  range ;  for  such  lime- 
stone valleys  can  only  represent  fragments  of  the  general 
limestone  outspread  preserved  in  deep  troughs  ;  (4)  by  the 
appearance  of  the  limestone  along  the  southeastern  foot  of 
the  mountain  range ;  as,  for  example,  in  southern  Berks 
and  Northampton  counties,  in  New  Jersey  and  New  York; 
(5)  by  large  areas  of  the  limestone  formation  between  the 
South  mountain  and  the  present  Atlantic  coast ;  as,  for 
example,  in  York,  Lancaster,  Chester  and  Montgomery 
counties  ;  but  chief  (6)  by  the  great  expanse  of  the  forma- 
tion (both  covered  and  not  covered  by  Trias  red  shale), 
through  the  60  mile  opening  in  the  range  above  described, 
far  away  towards  Maryland. 

The  numerous  relics  of  the  limestone  formation  No.  II, 
preserved  as  small  isolated  areas,  in  southeastern  Pennsyl- 
vania, taken  in  connection  with  the  isolated  areas  remain- 
ing in  the  heart  of  the  mountain  range,  suffice  to  prove  that 
it  originally  extended  in  an  unbroken  sheet,  and  probably 
in  a  nearly  horizontal  attitude,  over  all  the  United  States 
and  Canada  ;  and  that  it  probably  now  underlies  the  Creta- 
ceous and  Tertiary  belt  of  the  Atlantic  and  Gulf  States,  and 
perhaps  the  whole  of  the  Atlantic  ocean,  the  Gulf  of  Mexico 
and  the  Caribean  Sea,  covered  of  course  by  less  ancient 
Palseozic,  as  well  as  by  Mesozoicand  Kainozoic  formations. 

It  follows  that  the  uplift  of  the  South  mountain  must 
be  later  than  the  limestone  and  slate  formations  of  the 
Great  Valley.  The  date  of  the  birth  of  the  range  can  even 
be  fixed  with  a  near  approach  to  truth.  Its  upheaval  seems 
to  have  been  in  some  sense  the  cause  of  the  folding  of  all 
the  formations  of  middle  Pennsylvania  of  the  more  gentle 
waves  in  western  and  northern  Pennsylvania,  and  southern 
NewYork,  and  of  the  great  faults  of  Virginia  and  Tennessee. 


THE   GREAT   VALLEY.  293 

Now,  as  these  foldings  and  faults  affect  the  Coal  measures 
No.  XIII  at  the  top  of  the  series,  just  as  seriously  and  in 
precisely  the  same  manner  as  they  affect  the  lowest  forma- 
tions of  the  series,  the  sandstone  No.  I,  the  limestone  No. 
II,  the  slate  No.  Ill,  the  sandstone  No.  IV,  &c.,'  the  fold- 
ing action  must  have  taken  place  after  the  Coal  measures 
had  been  deposited.  On  the  other  hand,  the  Mesozoic 
(Trias)  red  shale  formation  next  following  in  age  the  Coal 
measures  lies  quietly,  as  we  have  seen,  over  the  upturned 
edges  of  the  older  series,  and  therefore  the  folding  action 
must  have  begun  and  ended  in  the  interval  of  time  between 
the  deposite  of  the  last  Coal  measures  (Permian  of  Green 
county)  and  the  first  or  bottom  beds  of  the  Mesozoic  strata 
which  we  see  lying  sometimes  upon  the  gneiss,  sometimes 
on  No.  I,  sometimes  on  No.  II,  along  a  line  east  and  west 
of  Norristown  in  Montgomery  county  and  elsewhere. 

If  the  folding  action  was  produced  by  a  push  of  the  whole 
Atlantic  coast  region  northwestward — as  it  evidently  was — 
for  there  is  a  general  overturning  of  the  tops  of  the  folds  in 
that  direction — the  push  must  have  been  connected  with 
the  rise  of  the  whole  range  of  the  South  mountains  from  its 
northern  to  its  southern  end ;  for  the  folded  country  is  a 
thousand  miles  long  by  five  hundred  broad  ;  and  the  im- 
mense height  of  the  upfolds  (anticlinals)  and.  depth  of  the 
downfolds  (synclinals),  amounting  variously  to  5  miles 
vertical,  shows  that  nothing  less  happened  than  a  shifting 
back  of  the  whole  Atlantic  belt  of  the  earth's  crust  north- 
westward a  distance  of  at  least  4.0  miles. 

The  mountains  thus  created  were  evidently  as  grand  as 
any  more  recently  produced  in  any  part  of  the  world,  the 
Andes  and  the  Himalayas  for  example.  But  these  consist 
of  the  last  deposits  of  the  ocean,  and  have  so  lately  ascended 
into  the  air  that,  although  their  destruction  is  going  o  n 
with  great  rapidity,  many  of  their  summits  are  still  more 
than  five  miles  high.  Whereas,  a  like  process  of  destruc- 
tion has  been  diminishing  our  old  Pennsylvania  mountains 
for  many  geological  ages,  so  that  not  a  trace  is  left  of  their 
original  magnificence  ;  the  edges  of  a  few  of  the  harder 
formations  make  continuous  ridges  and  these  not  more  than 
1000  or  2000  feet  above  the  general  surface  of  the  low  lands. 


294  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 


CHAPTER  XXIII. 
Why  is-  there  no  coal  in  the  Great  Valley  f 

The  answer  to  this  often  asked  question  is  easy,  short  and 
practical : — No  coal  beds  can  be  found  in  the  Or  eat  Valley 
because  the  Coal  Measures  which  once  covered  the  region 
have  all  been  swept  away  into  the  Atlantic  Ocean. 

The  geological  structure  of  the  Great  Valley,  taken  as  a 
whole,  is  simple  and  easy  to  understand.  It  has  large 
features  not  to  be  misunderstood  ;  in  fact  visible  at  a  glance 
upon  the  colored  geological  map  of  the  State,  where  a  band 
of  blue  (limestone)  and  a  band  of  gray  (slate)  run  side  by 
side  its  whole  length  across  the  State. 

I  will  recapitulate  in  a  few  short  sentences  the  principal 
points  of  the  last  chapter  so  that  they  may  be  kept  in  mind. 

1.  The  South  Mountain  sandstone  (No.  2)  is  older  than 
the  limestone  formation  in  the  valle}7,  and  passes  down 
under  it  to  make  a  foundation  for  the  whole  valley  and  for 
all  Pennsylvania,  New  York  and  Ohio  to  the  northwest  of  it. 

2.  The  limestone  strata  (No.  II.)  are  older  than  the  slates 
of  No.  Ill,  and  of  course  underlie  the  slate  belt ;  except 
where  the  slate  belt  is  thin  and  worn  away,   letting  the 
underlying  limestone  appear  in  the  coves.     The  whole  lime- 
stone belt  was  once  covered  by  the  slate  formation.     As  the 
cleaning  away  of  the  slate  from  off  the  limestone  belt  has 
been  always  going  on,  and  is  still  going  on,  only  isolated 
patches  of  the  lowest  part  of  the  slate  formation  remain 
here  and  there  on  the  limestone  belt. 

3.  The  slate  formation  (No.  III.)  is  older  than  the  North 
mountain  sandstone  and  passes  under  it  northward. 

4.  The  North  Mountain  sandstone  (No.  IV.)  descends  in 
its  turn,  northward,  beneath  the  formations  of  Pike,  Monroe, 
Carbon,  Schuylkill,  Perry  and  Fulton  counties. 

We  shall  see  in  succeeding  chapters  how  formations  II, 
III,  IV  rise  several  times  to  the  surface  in  middle  Penn- 
sylvania ;  every  time  making  a  limestone  valley  surrounded 


THE   GREAT   VALLEY.  295 

by  a  slate  belt  and  by  a  mountain  like  the  North  mountain. 
Then  we  shall  see  them  plunging  vertically  to  a  great  depth 
beneath  the  Allegheny  mountain,  along  the  top  of  which 
runs  the  first  bituminous  coal  basin.  Here  we  see  all  the 
formations  from  IV  to  XIII  piled  upon  them.  In  Huntingdon 
county  all  the  formations  from  IV  to  the  Broad  Top  Coal 
measures  (XV)  are  piled  upon  them.  Even  close  by  the  Great 
Valley,  in  Dauphin,  Schuylkill  and  Carbon  counties,  all  the 
formations  from  IV  up  to  the  top  of  the  Anthracite  Coal 
measures  (XVII)  remain  piled  upon  them  ;  the  limestone 
No.  II  lying  at- the  enormous  depth  of  30,000  feet  beneath 
the  city  of  Pottsville. 

Just  as  we  see  along  the  Little  Juniata  all  the  formations 
from  XIII  in  the  Allegheny  mountain  to  IV  in  Bald  Eagle 
mountain  rising  (southeastward)  one  after  the  other  to  make 
an  arch  h've  miles  high  in  the  air  over  the  Nittany  limestone 
and  slate  valley,  and  then  descending  (southeastward)  one 
after  the  other  in  Tussey  and  Terrace  mountains  beneath 
the  Broad  Top  coal  field — just  so  we  see  the  whole  pile  of 
formations  from  XII  to  IV  coming  straight  up  from  the 
underworld  in  the  Sharp  mountain,  Second  mountain  and 
North  mountain  to  make  a  similar  great  arch  in  the  air  over 
the  slate  and  limestone  belt  of  the  Great  Valley  . 

But  as  the  great  arch  over  Nittany  Valley  has  all  been 
swept  away,  and  it  is  useless  to  seek  for  coal  at  the  present 
surface  anywhere  between  the  Cambria  and  Clearfield  coal 
mines  and  the  Broad  Top  coal  mines,  so  the  arch  over  the 
Great  Valley  has  been  swept  away  and  it  is  useless  to  seek 
for  coal  south  of  Sharp  mountain  in  Schuylkill  and  Dauphin 
counties. 

The  coal  measures  have  been  swept  away  from  the  Great 
Valley  many  geological  ages  ago  ;  and  we  know  by  long 
experience  that  there  are  no  workable  beds  of  coal  in  any 
of  the  pile  of  formations  beneath  the  coal  measures,  except 
one  bed  in  No.  X  at  Duncannon,  and  that  is  worthless, 
and  has  been  swept  away  (with  the  rest  of  the  rocks)  from 
the  Great  Valley. 

To  illustrate  what  has  been  stated  above  in  a  few  words 
I  insert  two  cross  sections  which  will  speak  to  the  eye  better 
than  any  words  : — 


296  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

Section  through  Harrisburg  (page  277,  plate  2)  from  Dun- 
cannon  at  the  mouth  of  the  Juniata,  down  the  Susquehanna 
to  Columbia ;  and 

Section  across  Franklin  county  (page  281.  plate  4)  from 
Path  Valley  mountain,  through  Scotland  to  the  South 
mountains.* 

The  practical  importance  to  the  farmers  of  the  Great 
Valley  of  knowing  these  facts  and  understanding  the  above 
statement  is  evidently  considerable.  Why  should  they 
waste  time  and  money  in  digging  for  coal  where  it  cannot 
possibly  exist  ? 

There  is  not  a  trace  of  a  coal  bed  left  at  any  point  in 
any  county  along  the  whole  course  of  the  Great  Valley 
between  the  Hudson  and  the  Potomac;  nor  in  Amberson's 
valley  and  Path  valley  which  lie  behind  the  North  mountain 
in  Franklin  county  ;  nor  in  the  Fishing  creek  Trout  run 
Pine  Grove  valley  in  northern  Dauphin  and  Lebanon 
counties. 

All  reported  discoveries  of  coal  beds  are  mistakes  which 
a  few  words  will  suffice  to  explain. 

Along  the  center  line  of  the  Great  Valley,  between  the 
limestone  belt  and  the  slate  belt,  the  black  Utica  slate 
formation,  Ilia,  crops  out,  always  thin,  and  often  absent. 
In  other  words,  the  bottom  rocks  at  the  southern  edge  of 
the  slate  belt  are  often  as  black  as  the  black  slate  of  a  coal 
bed,  and  have  deceived  many  persons  into  digging  for  coal. 
When  weathered  down  they  make  the  jblack  clay  which  is 
so  conspicuous  in  the  great  Ironton  iron  mines  of  Lehigh 
county,  and  the  Moselem  mine  of  Berks  county.  They 
make  a  black  soil  at  other  places  along  the  lines  of  junction 
of  the  slate  and  limestone  lands.  But  no  impressions  of 
coal  plants  are  ever  seen  in  these  Utica  black  slates.  But 
occasionally  impressions  of  graptolites  may  be  observed  on 
them,  looking  like  lead  pencil  marks  on  paper;  some  of 
them  are  merely  forked  lines  ;  some  of  them  look  like  the 

*  These  sections  have  been  carefully  constructed  on  a  scale  of  4  miles  to  1 
inch  from  observed  outcrop  dips  in  the  Great  Valley  and  to  the  north  of  it 
so  numerous  that  no  material  error  can  be  imagined  in  the  general  shape  of 
the  arch  in  the  air  over  the  Great  Valley. 


THE  GREAT  VALLEY.  297 

edge  of  an  open  umbrella ;  others  like  holly  leaves.  They 
are  the  remains  of  curious  little  animals  which  swarmed  at 
the  surface  of  the  ancient  sea  ;  and  they  were. so  numerous 
that  their  dead  bodies  darkened  and  even  blackened  the 
mud  which  afterwards  was  hardened  into  slate  rock.  These 
graptolite  slates  are  exposed  to  view  in  the  horse  shoe  bends 
of  Connedogwinnet  creek  in  Cumberland  county. 

Discoveries  of  coal  are  reported  from  time  to  time  by 
people  living  in  front  of  tJie  North  mountain,  on  its  foot 
slopes.  Pieces  of  so  called  coal  are  frequently  found  lying 
on  the  surface  or  are  knocked  out  of  the  exposures  of  dark 
slate  ;  for  example,  near  Mercersburg  and  London  in  Frank- 
lin county.  But  these  pieces  are  not  indications  of  the 
existence  of  a  workable  coal  bed.  They  are  merely  black 
shale  layers  in  the  upper  part  of  the  slate  belt  (Hudson 
river  slate  formation  Illb,}  charged  with  the  animal 
carbon  of  dead  graptolites  and  trilobites  (water  bugs)  which 
lived  in  immense  numbers  in  the  waters  of  that  age.* 

Discoveries  of  coal  have  also  been  reported  from  behind 
the  North  mountain  in  Lebanon  county,  along  a  narrow 
belt  of  the  Marcellus  formation  (VIIK)  which  runs  entirely 
across  the  state  into  the  southern  states,  and  zigzags  through 
many  of  the  valleys  of  our  middle  counties.  It  is  a  narrow 
belt  of  outcropping  black-slates  very  much  resembling  the 
black-slates  which  cover  coal  beds  in  the  coal  regions.  But 
it  is  slate  and  not  coal.  People  who  see  it  in  a  hillside  in 
the  form  of  a  regular  bed,  and  very  black,  looking  a  good 
deal  like  the  outcrop  of  a  coal  bed,  think  that  it  is  merely 
the  bad  edge  of  a  good  coal  bed.  They  who  try  to  burn  a 
piece  of  it  in  a  blacksmith's  fire  find  that  it  will  blaze  a 
little  at  first  and  then  remain  red  hot  and  throw  out  a  good 
deal  of  heal;;  but  when  they  take  the  piece  out  of  the  fire, 
it  is  nothing  but  a  stone.  This  however  does  not  discourage 
them  ;  there  are  plenty  of  wandering  miners  seeking  a  job 
who  assure  them  that  if  they  will  "go  down  on  the  bed"  it 
will  turn  to  good  coal.  In  almost  every  county  in  the. state 

*  The  chemical  analysis  of  a  specimen  of  this  deceptive  kind  of  coal,  found 
back  of  Mercersburg  in  Franklin  county,  will  be  given  in  a  subsequent 
chapter,  where  the  rocks  of  the  slate  belt  are  described. 


298  GEOLOGICAL   SURVEY    OF  PENNSYLVANIA. 

lying  between  the  North  mountain  and  the  Allegheny 
mountain  considerable  sums  of  money  have  been  wasted  in 
sinking  shafts  and  drifting  tunnels  into  this  belt  of  Mar- 
cellus black  slate  during  the  last  fifty  years,  but  no  valuable 
coal  bed  has  ever  been  obtained.* 


CHAPTER  XXIV. 


The  Great  Valley  Limestone  No.  II. 

Having  described  in  the  last  chapters  the  general  topo- 
graphical and  geological  features  of  the  Great  Valley,  I 
shall  give  in  this  and  following  chapters  descriptions  of  its 
two  principal  formations  in  sufficient  detail  to  make  them 
understood  : — (1)  the  limestone  beds  in  the  Lehigh  region  ; 
the  quarries  between  the  Schuylkill  and  Susquehanna  ;  the 
quarries  west  of  the  Susquehanna  ; — (2)  the  slate  belt  with 
its  roofing  slate  quarried  in  the  Lehigh  region  ;  and  its 
clay-limestone  beds  on  the  Susquehanna. 

The  reader  will  thus  be  prepared  for  a  description  of  these 
formations  where  they  have  been  preserved  in  synclinal 
basins  in  Chester,  Lancaster  and  York  ;  and  where  they  are 
brought  up  to  the  present  surface  by  anticlinal  waves  in 
Fulton,  Perry,  Juniata,  Mifflin,  Bedford,  Blair,  Hunting- 
don, Centre,  Clinton  and  Lycoming  counties. 

The  exhibition  is  so  great,  the  wealth  of  observations  so 
over-abundant,  that  the  most  condensed  summary  of  the 
facts  published  in  the  reports  of  the  survey  will  seem  to 
need  ,«ome  apology  for  its  length.  But  it  is  an  embarass- 

*  In  Perry  and  Juniata  counties  thin  streaks  of  very  slaty  Marcellus 
coal  cross  the  bed  of  the  Juniata  river,  and  much  money  was  formerly 
wasted  in  following  them  into  the  hillside ;  all  money  thrown  away. 
Peoples'  experience  of  Marcellus  black  slate  mining  in  other  states  has 
always  been  the  same. — I  have  added  this  instance  of  deceptive  coal  pros- 
pecting, because  it  is  of  importance  to  the  citizens  of  Lebanon  and  Dauphin 
Bounties  in  the  Great  Valley.  It  will  find  its  place  again  in  a  future  chapter 
on  the  Marcellus  formation. 


THE   GREAT   VALLEY.  299 

ment  of  riches.     I  can  only  strive  to  classify  the  subjects 
.properly,  and  avoid  repetitions.* 


Subdivision  of  No.  II. 

In  New  York  state  No.  II  is  subdivided  into  (1)  Trenton, 
Black  river  and  Bird? s-eye  limestone  at  the  top  ;  (2)  Chazy 
limestone  in  the  middle  ;  and  (3)  Calciferous  sandstone  at 
the  bottom,  resting  on  the  Potsdam  sandstone,  f 

In  Pennsylvania  along  the  Great  Valley  belt  the  only 
distinct  division  of  it  that  can  be  made  is  into  upper  purer 
limestone  beds,  ancj  lower  magnesian  cherty  and  sandy  beds  ; 
that  is,  if  the  New  York  names  are  to  be  used,  into  Trenton 
limestone  on  top,  and  Calciferous  sandstone  for  all  the  rest 
of  it  down  to  the  bottom  4 

*The  detailed  descriptions  of  quarries  may  seem  needless  ;  but  they  are 
only  specimens  on  a  large  scale  of  the  economical  geology  of  the  state,  and 
teach  the  structural  geology  in  a  better  manner  than  it  could  be  taught  by 
verbal  general  statements.  It  is  a  kind  of  object  teaching.  It  shows  the 
difficulties  and  the  successes  of  field  work.  It  points  out  localities  for  study. 
Above  all,  it  has  a  business  value.  The  quarries  of  the  Great  Valley  are 
selected  because  they  are  a  numerous,  connected  and  tj'pical  series,  and 
have  played  a  master  role  in  the  history  of  the  growing  wealth  of  Pennsyl- 
vania. 

fThe  discussion  on  the  "Quebec  group"  of  the  Reports  of  the  Canada 
Survey  do  not  concern  us  in  Pennsylvania  ;  but  any  geologist  who  desires 
to  know  the  last  word  on  it  will  find,  it  in  two  short  communications  in 
Science,  Dec.  26,  1890,  page  359  ;— one  by  R.  W.  Ells,  repeating  his  opinion 
(published  in  the  Canada  Survey  Report  of  1887-8,  pp.  83,  84,  K)  viz.:  "That 
these  [Quebec]  rocks  represent  a  peculiar  development  of  strata  of  Trenton 
age,  and  probably  even  down  in  that  formation,"  sustaining  Logan's  old 
view ; — the  other,  by  Alfred  R.  C.  Selwyn,  the  Director  of  the  Canada  Sur- 
vey, opposing  W.  Ami's  views,  and  repeating  his  own  opinion  (as  against 
Logan)  published  in  187(>-7,  that  the  Quebec  city  rocks  are  certainly  of  Hud- 
son river  (Lorraine,  Cincinnati)  age,  overlying  the  Trenton. — I  may  be  per- 
mitted  to  add  here  that  neither  my  conversations  with  Logan  while  he  lived, 
nor  the  study  of  his  written  statements  of  the  case,  removed  my  objections 
to  what  I  regarded  his  extraordinary  and  improbable  theory  of  an  expan- 
sion of  a  part  of  formation  ^o.  II  eastward  into  a  great  local  formation 
named  by  him  "the  Quebec  group." 

f  Writing  of  the  magnesian  part  of  the  formation  in  the  Lehigh  region,  Prof. 
Prime  says  :  "  Lithologically  it  seems  to  be  impossible  to  make  any  distinc- 
tion between  the  limestones  which  must  belong  to  different  geological  hor- 
izons ;  for  limestones  from  the  top  of  the  series,  close  to  the  Trenton  lime- 
stone, look  quite  as  much  like  those  from  just  above  the  Potsdam  [C'hiques] 


300  GEOLOGICAL   SUEVEY   OF   PENNSYLVANIA. 

Even  in  the  back  valleys  of  Middle  Pennsylvania  no 
better  sub-division  of  the  whole  formation  can  be  made ; . 
although  the  unbroken,  uncrumpled  condition  gives  a 
chance  to  put  its  beds  in  vertical  order  which  is  not  possible 
in  the  Great  Valley.  For  we  there  see  only  a  gradation 
from  the  purer  beds  at  the  top  downward  into  middle  cherty 
beds  and  lower  sandy  and  cherty  beds,  without  any  strongly 
marked  general  horizons  of  change. 

Prof.  Stevenson's  railroad  section  of  4519  feet  of  it  in 
Bedford  county,  Snake  Spring  township  (Report  T2,  p.  93) 
will  illustrate  the  fact. 

420'  of  Trenton  blue  flaggy  limestones,  He;  succeeded 
downwards  by  thicker  beds  of  light  blue  or  bluish  grey ; 
mostly  not  silicious  ;  many  yielding  superior  lime.* 

1351'  of  Chazy  beds,  in  part  116 ;  highest  beds  hardly 
silicious ;  white  chert  balls  begin  to  appear  (descending) 
600'  below  the  top ;  next  400'  cherty  limestones  ;  further 
down  more  and  more  silicious  ;  black  chert  appears  at  1200' 
from  top  ;  streaks  of  chert  so  numerous  that  the  weathered 
surface  is  fretted  with  ridges. f 

420'  of  concealed  measures. 

419'  of  limestone,  mostly  silicious. 

400'  (estimated)  concealed  measures. 

175'  (exposures  imperfect)  limestone,  silicious. 

150'  concealed  measures. 

300'  (Calciferous  in  part,  Ha)  beds  of  cherty  calcareous 
grit ;  fretted  weather  surfaces  show  the  abundance  of  thin 
'chert  layers. 

90'  concealed  measures. 


sandstone  (No.  1)  as  do  specimens  taken  from  two  beds  in  the  same  quarry 
not  ten  feet  vertically  apart.  No  traces  either  lithological  or  palseontological 
have  been  found  by  which  the  Calciferous  sand  rock  (said  by  Rogers  to  occur 
near  Easton)  can  be  recognized  or  differentiated  from  the  other  formations." 
(Report  D2,  page  11.) 

*The  line  of  separation  of  the  Ulica  slate  No.  Ill  from  the  underlying 
Trenton  limestone  No.  II,  is  almost  abrupt  where  well  seen  in  Milligan's 
Cove  (T2,  p.  93).  Fossils  rare;  Calymene  senaria  and  Strophomena  alter- 
nata,  obtained  from  one  of  the  highest  beds.  Columnaria  alveolata  was 
seen  in  Morrison's  cove  (p.  94). 

f  Cyathophylloid  fossils  got  near  the  base  of  this  subdivision  along  the 
Juniata. 


THE  GREAT  VALLEY.  301 

620'  of  limestone  beds  sandy  but  with  very  little  chert ; 
most  of  them  might  be  called  a  calcareous  sandstone. 

175'  concealed  measures — Total,  4519  feet.* 

No  one  can  doubt  that  the  uppermost  beds  of  the  lime- 
stone belt  represent  the  Trenton  outcrop  on  the  Mohawk 
river.  We  can  therefore  safely  use  that  term  in  Pennsyl- 
vania; and  typical  Trenton  fossils  occur  in  sufficient  numbers 
to  justify  its  use. 

Chazy  fossils  occur  sparingly  in  the  middle  magnesian 
beds,  and  I  see  no  objection  to  retaining  that  name. 

But  Calci/erous  sandstone  was  from  first  to  last  an  un- 
fortunate New  York  term  and  ought  to  abandoned.  The_ 
beds  are  limestone,  riot  sandstone  beds,  although  they  are 
often  sandy,  and  have  an  abundance  of  silica  in  the  form 
of  chert ;  but  many  of  the  lowest  beds  are  nearly  pure 
magnesian  limestone,  layers. f 


CHAPTER  XXV. 

No.  II  in  the  LeMgh  region. $ 

The  beds  of  limestone  along  the  Lehigh  river,  where  they 
have  been  exposed  to  special  view  in  very  extensive  quarries 
worked  for  the  Allentown,  Crane  and  Thomas  furnaces,  are 
seen  to  vary  much  in  texture,  color,  hardness,  structure  and 
chemical  composition. 

Some  beds  are  compact,  others  crystalline. 

Blue  and  dove  colors  prevail ;  but  some  beds  are  almost 
white,  others  nearly  black  ;  and  the  blue  limestones  are  of 
all  shades  from  lightest  to  darkest  blue. 

*  It  is  quite  probable  that  towards  the  northern  edge  of  Bedford  county  a 
greater  thickness  of  this  formation  is  brought  to  the  surface ;  but  no  details 
were  obtained  there.  (T2,  p.  94. ) 

1 1  am  unwilling  to  add  another  name  to  our  already  copious  nomenclature 
by  calling  them  the  Allentown,  or  the  Easton,  or  the  Reading,  or  best  of  all 
the  Bethlehem  formation,  which  last  would  be  unexceptionable,  if  distinct 
limits  could  be  assigned  to  it,  which  cannot  be  done.  I  prefer  therefore  to 
distinguish  vaguely  the  lower,  middle  and  upper  portions  by  the  old  num- 
bers, Ha,  life,  He. 

JI  take  the  substance  of  this  chapter  from  Prof.  Prime's  report,  D,  D2,  D3. 


302  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

The  hardest  beds  are  commonly  those  of  dark  blue  color  ; 
others  are  soft,  disintegrating  to  |  or  %  of  an  inch  on  a 
weathered  surface  so  that  they  can  be  rubbed  to  loose  sand 
between  the  fingers.  Groups  of  the  harder  beds  make  little 
ridges  which  determine  to  some  extent  the  direction  of 
brooks  and  streams  on  the  surface.* 

The  softer  beds  give  lines  of  sink-holes  leading  down  to 
caverns  through  which  subterranean  streams  flow,  some- 
times reappearing  at  the  surface  in  large  springs,  at  other 
times  emptying  into  the  larger  river  valleys.  Many  of  the 
longitudinal  vales  are  ancient  caverns  which  have  lost  their 
roofs. 

Two  different  kinds  of  structure  are  well  known  to  the 
farmers  :  rock  limestone  and  slaty  limestone.  The  massive 
beds  of  rock  limestone  are  accounted  to  make  a  better  farm 
lime,  or  stronger  manure  ;  and  this  is  probably  a  correct 
opinion,  for  the  slaty  limestone  owes  its  structure  to  its  greater 
percentage  of  silicate  of  alumina,  which  does  not  act  as  a 
manure.  Some  very  pure  lime  or  lime-magnesia  (dolomite) 
beds  with  a  very  slight  percentage  of  silica  are  extremely 
thin-bedded,  slaty  looking,  and  ringing  when  struck. — Some 
shaly  beds  have  so  large  a  percentage  of  alumina  that  they 
decompose  to  clay. 

A  very  strange,  peculiar  and  entirely  mysterious  feature 
of  some  beds  is  a  structure  resembling  a  mass  of  clam  shells 
closely  packed  together  with  their  round  sides  uppermost. 

The  chemical  composition  varies  between  a  pretty  pure 
carbonate  of  lime,  and  a  nearl}'-  correct  dolomite  (half  lime, 
half  magnesia),  but  always  with  some  amount  of  silica, 
alumina,  iron,  phosphorus,  carbon  and  water  of  crystalliza- 
tion. And  it  seems  that  the  lower  (more  southern)  beds  of 
the  formation  are  more  magnesian  (on  the  whole)  than  the 
upper  (more  northern)  beds.f 

*Well  exemplified  in  the  steep  bluff  of  hard  limestone,  bounding  the 
Jordan,  |  m.  N.  W.  of  the  Thomas  I.  Co.'s  mine,  No.  149  of  the  map.  Ex- 
tensive quarries  of  good  curbing  and  crossing  stones  are  worked  on  the  N. 
bank  of  the  Jordan,  f  m.  E.  of  Orefield. 

f  Such  is  the  opinion  of  Prof.  Roepper  of  Bethlehem,  and  Mr.  W.  Firm- 
stone  of  the  Glendon  I.  Works,  whose  analyses  have  been  numerous  and 
intentionally  directed  to  the  discrimination  of  the  beds  as  fluxes.  It  is  cer- 


THE   GREAT   VALLEY.  303 

The  dolomite  beds,  however,  are  distributed  among  the 
limestone  beds  in  a  curiously  capricious  manner,  showing 
no  kind  of  order  or  system  anywhere  throughout  the  form- 
ation.* This  is  the  case  high  up  in  the  series  ;  as  appears 
from  analyses  of  10  of  the  beds  of  Grove  quarry  in  Black 
Log  Valley,  made  for  Orbisonia  furnace  in  Huntingdon 
county  ;  where  the  Trenton  formation  is  exposed,  about 
500'  thick,  dipping  about  60°,  and  composed  of  dark  blue- 
and  gray  soft  argillaceous  limestones  alternating  with  blue 
lime  shales  (more  abundant  toward  the  top);  the  quarry  be- 
ing opened  in  lower  beds,  measuring  22,  20,  10,  24,  18,  21, 
20,  32,  30,  and  72  inches  thick  respectively  ;  and  the  re- 
spective percentages  of  carbonate  of  lime  being  (in  whole 
numbers)  90,  85,  90,  74,  81,  83,  81,  82,  85,  47,  the  last  and 
lowest  a  dolomite.  (F,  p.  260.) 

Damourite  (hydromica)  layers  only  half  an  inch  or  more 
in  thickness  part  the  limestone  beds  from  one  another  all 
through  the  formation,  and  in  such  numbers  that  a  hun- 
dred of  them  have  been  counted  in  a  single  outcrop.  They 
are  regularly  interstratified  with  the  limestone  beds,  and 
are  decomposed  by  the  weather  into  clay.f 

But  the  damourite  is  sometimes  seen  as  leaves  thinner 
than  paper,  completely  intermingled  with  the  limestone  and 
so  thoroughly  incorporated  as  to  make  a  separation  of  the 
two  impossible.  The  flakes  of  the  mica  in  this  latter  case 
cross  the  body  of  the  limestone  in  all  directions.^ 

tain  that  the  cement  beds,  so  rich  in  alumina,  are  at  the  top  of  the  magnesian 
series,  or  in  the  Trenton  formation  II  c. 

*Of  this  more  will  be  said  in  describing  the  McCormick  quarries  at  Har- 
risburg.  Here  I  will  merely  give  Mr.  J.  B.  Britton's  analyses  of  viine  beds 
in  Troxell's  quarry,  Jordan  Bridge  of  the  C.  <fe  P.  R.  R. ;  A.  the  lowest  bed  ; 
I.  the  highest ;  A.  to  E.  worked  for  flux  for  Crane  I.  C.  furnaces,  F.  to  I.  re- 
jected. 

Garb,  lime, 85.2,76.8,78.2,61.5,70.1,63.9,71.9,58.3,89.5; 

Garb,  mag., 5.9,17.0,14.5,26.8,20.1,    3.1,    8.3,    2.3,    0.6; 

Silica, 7.1,    4.1,    4.7,    7.3,    6.1,27.7,14.6,33.2,    8.2. 

For  the  percentages  of  phosphorus,  alumina,  iron,  etc.,  and  for  many 
other  similar  limestone  analyses,  see  Prime's  Report,  D2,  1878,  page  16  to  20. 

f  Hydromica  is  a  hydrous  silicate  of  potash  and  alumina. 

J  Prof.  Prime  adds  that  this  may  excite  a  suspicion  that  the  damourite  has 
been  a  subsequent  production,  although  the  limestone  rock  is  fresh  and  hard 
and  shows  no  sign  of  water  percolation,  or  mineralogical  change  of  any 


394  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

The  great  mass  of  damourite  slate  (primal  slate)  at  the 
bottom  of  the  formation,  with  its  line  of  limonite  iron  ore 
banks,  has  been  described  in  a  previous  chapter.  A  large 
quantity  of  damourite  slate  appears  at  the  top  of  the  forma- 
tion also  in  some  places  along  the  line  of  contact  with  the 
slate  belt ;  and  in  this  upper  outcrop  occur  the  great  limo- 
nite mines  of  Ironton  in  Lehigh  county,  and  Moselem  in 
Berks  county  ;  also  as  I  believe,  the  Corn  wall  magnetic  iron 
ore  mine  in  Lebanon  county  ;  and  the  Path  Valley  limonite 
mines  in  Franklin  county.* 

Cliert  is  abundant  in  the  lower  portion  of  the  great  lime- 
stone formation  No.  II,  both  in  scattered  balls,  and  in  lens- 
shaped  masses.  The  chert  is  sometimes  honeycombed,  or 
contains  cavities  from  which  rhombohedral  crystals  of  dolo- 
mite have  been  dissolved  out. 

Sandstone  beds  are  sometimes  met  with  between  the  lime- 
stones ;  and  they  help  much  to  prove  the  mechanical  deposit 
of  the  whole  formation.  A  few  only  have  been  noted;  the 
largest  not  2'  thick  ;  all  in  the  magnesian  beds  ;  and  all  in 
company  of  damourite  ore  bearing  slates. f 

kind. — To  my  mind  it  is  only  another  proof  that  the  limestone  was  not  a 
chemical  precipitate,  but  a  regular  mechanical  sediment ;  and  that  the  rivers 
which  brought  the  sediment  to  the  sea  carried  large  quantities  of  floating 
flakes  of  mica  from  some  mica  schist  region  ;  sometimes  spread  the  mica 
flakes  when  most  abundant  in  thin  layers  ;  at  other  times  when  less  abund- 
ant the  mica  flakes  would  slowly  settle  singly  to  the  bottom  and  stand  or  lie 
as  they  happened  to  touch  bottom.  A  typical  locality  for  this  exhibition  is 
the  limestone  exposure  in  the  bottom  of  the  Ironton  R.  R.  Co.'s  iron  mine. 

*It  has  been  already  said  that  some,  if  not  many,  of  the  smaller  limonite 
banks  of  Northampton  and  Lehigh.  county,  located  in  the  middle  region  of 
the  limestone  belt,  may  have  been  produced  by  damourite  slate  partings  in 
the  middle  of  the  formation.  But  many  more  of  them  are  connected  with 
synclinal  folds  in  which  the  slates  of  III  have  once  lain,  but  are  now  swept 
away ;  these  mines  must  be  referred  then  to  the  damourite  slates  at  the  top 
of  II.  But  see  a  subsequent  chapter  for  reasons  to  modify  this  statement  so 
as  to  make  it  refer  to  the  top  of  the  magnesian  limestones  and  not  to  the  top 
of  the  Trenton. 

f  Instances  are : — A  sandstone  bed  19  inches  thick,  cut  by  the  L.  &  S- 
RR.  just  west  of  the  round  house  at  Bethlehem  ;  quite  conformable  ;  lower 
9"  a  pure  quartzite  ;  upper  10"  more  of  a  conglomerate  of  quartzite  with  some 
limestone  ;  evidently  a  breccia  of  two  adjoining  beds  produced  by  pressure. 
(D3,  p.  172.) — A  thin  bed  of  saccharoidal  sandstone  at  the  Breinig  mine 
between  Trexlertown  and  Breinigsville  ;  analysis  showed  quartz,  with  small 
quantities  of  damourite  ;  evidently  a  sandy  layer  in  the  ore  bearing  potash 


THE   GREAT   VALLEY.  305 

Oolitic  lime  stone  beds  are  frequently  encountered,  but  not 
confined  to  any  fixed  horizon  in  the  series  ;  no  use  can  be 
made  of  them  by  the  field  geologist  in  establishing  the  order 
of  the  beds  ;  for  they  are  very  local  and  irregular,  the 
oolitic  character  often  disappearing  from  a  bed  only  a  few 
feet  from  where  it  is  strongly  pronounced.  The  round  grains 
are  generally  a  little  larger  than  sturgeon's  roe  ;  sometimes 
loosely  scattered  through  a  crystalline  limestone  ;  at  other 
times  so  abundant  that  there  is  hardly  room  between  them 
for  the  cementing  paste.* 

Breccia  beds.  It  frequently  happens  that  one  limestone 
bed  lying  between  two  others  is  a  sort  of  conglomerate,  but 
differing  from  pudding  stone  conglomerates  in  two  features: 
— (1)  The  fragments  are  all  and  always  angular,  sharply 
angular,  and  not  rounded  or  rolled  in  water  ; — (2)  These 
angular  fragments  are  not  composed  of  various  kinds  of 
rocks,  but  are  all  limestone,  and  all  of  the  same  sort  of  lime- 
stone, whether  more  or  less  magnesian  ; — (3)  These  beds 
moreover  are  to  be  met  with  in  all  parts  of  the  limestone 
belt,  from  the  bottom  magnesian  beds,  to  the  top  non- 
magnesian  beds. — It  is  evident  then  that  such  beds  are  not 
of  the  nature  of  gravel  conglomerates  formed  on  ancient 
shores  by  the  action  of  waves  ;  but  that  they  are  breccias, 
that  is,  broken-up  or  smashed  layers  of  limestone,  crushed 
by  the  pressure  force  of  an  earth  movement  from  the  south, 
the  fragments  of  the  bed  remaining  in  their  places,  and 
being  afterward  cemented  together  by  percolating  lime 
waters  depositing  calcite.f 

slates.  (D,  p.  34.) — A.  similar  layer,  only  one  inch  thick,  occurs  in  the  ore 
slate  of  the  Schwartz  and  Fogel  mine.  (D,  p.  36.)— A  bed  of  sandstone  5" 
thick  is  interstratified  in  the  quarry  next  but  one  to  the  Brewery  on  the 
Delaware;  and  another  5"  to  8"  thick  in  the  quarry  next  the  Brewery,  in 
company  with  thin  beds  of  damourite  and  an  oolite  limestone.  (D3,  171.) 

*  The  fish-roe  grains  of  oolitic  limestone  have  been  usually  explained  as 
grains  of  sand  around  which  the  carbonate  of  lime  has  concreted  itself. 
Recently  it  has  been  proven  by  the  microscope  that  some  limestones,  if  not 
all  of  them,  are  made  oolitic  by  rounded  fragments  of  fossil  bryozoa.  They 
are  apparently  the  lime  mud  of  destroyed  coral  reefs  in  which  lie  enclosed 
small  bits  of  coral  rounded  by  the  waves  but  not  reduced  to  mud. 

t  Prof.  Prime  notes,  as  typical  localities,  Mary  Kohler's  quarry  £  m.  W. 
of  Whitehall  station  (L.  V.  RB.),  and  an  exposure  on  the  Jordan  just  N.  of 
Helfrich's  spring.     (D2,  p.   13.)     He  gives  an  analysis  of  the  M.   Kohler 
breccia  on  page  15. 
20 


306  GEOLOGICAL   SURVEY    OF   PENNSYLVANIA. 

Cement  beds  occur  somewhere  in  the  Trenton  limestone 
(//  c),  along  the  edge  of  the  slate  belt,  which  crosses 
the  Lehigh  river  at  Coplay.  Here  are  the  quarries  of  the 
Coplay  Cement  Works,  and  of  the  Lehigh  Cement  Works 
on  the  west  bank  ;  and  the  quarries  of  the  Old  Lehigh  Ce- 
ment works  and  of  the  Allen  Cement  Company  on  the  east 
bank.  They  are  traceable  westward  to  the  Ironton  *  mine  in 
Lehigh  county  ;  and  eastward  all  along  the  road  from  Sieg- 
fried's Bridge  to  Nazareth  in  Northampton  county  ;  and 
again  in  the  neighborhood  of  Martin's  Creek  village  at  the 
Delaware,  f  A  subsequent  chapter  will  be  given  to  these 
cement  beds,  their  quality  and  use. 

The  folded  stratification  of  No.  II. 

The  limestone  quarries  along  the  Lehigh  show  the  folded 
and  compressed  condition  of  No.  II ;  and  yet  much  of  it  is 
seen  to  be  less  complicated  than  was  formerly  supposed  ; 
merely  lifted  and  thrown  into  waves ;  as  for  example  in 
the  Lehigh  Valley  Iron  Co.'s  long  quarry  at  Coplay,  the 
north  end  of  which  shows  two  short  sharp  little  upfolds 
disturbing  an  otherwise  almost  horizontal  outspread.:}: 

The  prevalence  of  cleavage  planes,  generally  sloping 
southeast,  obscures  the  stratification,  and  sometimes  almost 
obliterates  it.  Sometimes  it  is  impossible  to  read  the  dip, 
the  beds  being  broken  up  into  a  mass  of  blocks  of  irregular 
shape.  § 

While  the  majority  of  the  dips  are  towards  the  south, 

*D2,  p.  57,  58.  Dr.  Genth's  analysis  of  a  sample  from  here  reads  :  Garb, 
lime,  82.05  ; insoluble  silicates  of  alumina,  etc.,  15.07  ;  ferrous  and  mang.  car- 
bonates, 0.09;  carb.  magnesia,  0.17;  water,  2.42;  carbon  and  undetermined 
matter,  0.20. 

f  D3,  p.  164. 

\  See  the  beautiful  photo-lithograph  picture  in  D2,  plate  2,  p.  54.  The  south 
end  of  this  quarry,  on  the  contrary,  shows  the  limestone  beds  thrust  up 
suddenly  into  a  vertical  attitude,  and  then  turned  sharply  over  in  a  larger 
anticlinal  with  a  squeezed  top.  (See  plate  1  in  the  same  report  D2.)  What 
is  exceedingly  interesting,  one  of  the  upfolds  in  plate  2  is  crossed  on  top  by 
horizontal  beds,  proving  the  great  amount  of  slip  and  slide  of  bed  on  bed 
which  took  place  during  the  movement. 

§  As  in  H.  Stein's  quarry  2  m.  S.  W.  of  Fogelsville,  a  picture  of  which  is 
given  in  report  D,  p.  9  ;  also  the  Hokendauqua  quarry  close  to  the  L.  V.  R.  R.; 
the  Coplay  quarry ;  and  those  just  outside  of  Catasauqua  (D2,  p.  54). 


THE   FOLDED   STRATIFICATION    OF   NO.  II.  307 

there  are  many  exposures  of  north  dips,  but  not  enough  to 
account  for  all  the  south  dips  ;  consequently  many  of  the 
south  dips  must  be  overturns  ;  and  this  is  proven  by  over- 
turned compressed  anticlinal  folds  exposed  in  the  quarries 
along  the  Lehigh  river.* 

The  magnesian  limestone  lowest  beds  are  said  by  Prof. 
Prime  (D2,  p.  55)  to  be  always  conformably  superimposed 
upon  the  Chiques  ("Potsdam")  quartzite,  even  when  the 
latter  show  steeper  dips  than  those  of  the  neighboring  lime- 
stone beds. 

The  Trenton  limestone  uppermost  beds  also,  as  a  rule, 
conformably  underlie  the  slate  beds  of  No  III ;  although  in 
some  places  both  are  seen  inverted  so  as  to  place  the  slates 
underneath  the  limestones. f 

Fossils  in  Lehigh  county  are  very  rare  in  the  limestones; 
too  few  to  serve  the  palaeontologist  who  wishes  to  use  them 
for  subdividing  the  whole  into  formations  of  separate  ages. 
A  Maclurea,  and  some  cross  sections  of  EuompTialus 
(species  unknown)  were  first  found  in  a  quarry  2  m.  E.  of 
Ballietsville,  indicating  the  Chazy  age  of  the  beds.  Then 
three  casts  of  Monocraterion  (worm  burrows)  were  found  in 
the  bed  of  the  Jordan,  just  W.  of  Helfrich's  spring.:}:  A 
dozen  specimens  of  Lingula  (species  unknown)  were  found 
in  Schadt's  quarry,  £  m.  N.  W.  of  Helfrich's  spring.  A 

*One  such  at  Catasauqua  passes  through  a  hill  and  is  quarried  on  the  east 
and  west  sides  of  the  hill.  The  two  sections  of  the  arch  thus  made  were 
photographed  and  lithographed  for  plate  3  (Rau's  quarry)  and  plate  4 
(Weaver's  quarry)  in  Prof.  Prime',s  report  D2.  The  slip  and  slide  of  the 
beds  on  one  another  in  the  pinch  of  the  arch  is  finely  shown  in  Rau's  quarry. 

fThe  anticlinals  and  synclinals  of  Lehigh  county  are  located  and  de- 
scribed by  Prof.  Prime  in  D2,  pp.  55  to  57. 

\  Here  is  a  cave  and  a  water  sink.  Prof.  Torell  indentified  these  casts  as 
belonging  to  his  Swedish  Cambrian  genus;  the  name  M.  lesleyi,  will  prob- 
ably be  abandoned  for  Scolithus,  as  the  funnel-shaped  end  of  the  cast  is 
often  seen  in  the  Cambrian  Scolithus.  (For  figures  and  description  see 
Appendix  to  Report  D2,  p.  80.)  But  the  presence  of  this  fossil  cast  is  no 
evidence  of  the  Cambrian  age  of  the  magnesian  limestone  beds.  As  Prof. 
Prime  says  in  his  summary  of  evidence  of  their  Chazy  and  Calciferous  age 
there  is  no  sign  of  a  stiatigraphical  break  in  the  series  from  the  top  of  the 
acknowledged  Trenton  beds  to  the  bottom  of  the  Magnesian  series.  "  There 
is  not  a  particle  of  evidence  that  any  of  these  limestones  belong  to  Huronian 
(as  suggested  by  Dr.  T.  S.  Hunt)  or  older  epochs ;  all  the  facts  point  the 
other  way."  (D3.  p.  163.) 


308  GEOLOGICAL   SURVEY    OF   PENNSYLVANIA. 

poor  fragment  of  an  Orthoceras  was  found  in  a  loose  rock 
1000'  N.  of  the  tavern  at  Scherersville. 

Fossils  in  Northampton  county  have  been  got  from  the 
middle  and  upper  limestones  ;  thus — Maclurea  (or  Euom- 
phalus]  in  Dech's  quarry,  \\  m.  S.  W.  of  Bath  ;  probably 
of  Chazy  age. — Encrinal  stems,  not  far  N.  E.  of  last; 
Trenton  age-,  also  abundant  in  the  upper  beds  of  Krock's 
quarry  at  Christian  spring ;  also,  from  there  eastward  to  i 
m.  E.  of  Nazareth,  wherever  the  limestones  are  weathered; 
also,  in  Russ'  quarry,  just  S.  W.  of  Nazareth  (here  in  com- 
pany with  a  few  Orthis  testudinaria);  also,  on  Knecht's 
farm  close  to  Bushkill  creek,  £  m.  S.  W.  of  Stockertown 
(here  in  company  with  Ohcetetes  lycoperdon  and  0.  testudi- 
naria}; also,  at  quarry  opposite  Churchville  church,  in 
upper  weathered  rocks  (the  lower  beds  affording  Leptcena 
sericea,  0.  testudinaria,  and  0.  pectinella);  also  £  m.  E.  of 
Kellers  tavern  (two  or  three  encrinal  outcrops).  All  these 
exhibitions  prove  that  encrinal  stems  mark  theTrenton  out- 
crop.— In  the  quarries  on  the  Delaware  just  S.  of  Ho  well's 
cotton  mill  are  found  Leptcena  sericea,  Orthis  pectinella, 
O.  testudinaria,  Strophomena  alter  nata,  Chcetetes  lycoper- 
don. and  one  or  two  other  undetermined  forms,  lying  in 
colonies  of  from  20  to  200  individuals,  and  not  scattered 
through  the  rocks,  which  are  evidently  of  Trenton  age. 


GREAT   VALLEY   LIMESTONE   QUARRIES.  309 


CHAPTER  XXVI. 

Limestone  quarries  of  tlie  Great  Valley  between  the  Schuyl- 
kill  and  the  Susquehanna  rivers. 

Looking  from  the  car  window  of  a  train  moving  westward 
from  Reading  towards  Harrisburg  a  geologist  is  struck  with 
the  remarkable  fact  that  the  limestone  beds  cut  by  the  line, 
or  exposed  in  quarries  within  his  view,  seem  to  be  all 
dipping  southward,  and  usually  at  low  angles.* 

But  after  passing  Myerstown  station,  a  broad  flat  plain 
of  limestone  or  shale  begins  to  spread  out  south  of  the  rail- 
road, showing  few  exposures  of  any  kind.  At  Lebanon, 
across  this  plain  runs  the  branch  railroad  to  the  Cornwall 
iron  mines,  and  along  this  railroad  quarries  and  natural  ex- 
posures show  the  limestone  formation,  lying  comparatively 
flat ;  that  is,  rolling  with  gentle  north  and  south  dips  ;  the 
last  south  dips  sinking  beneath  the  Cornwall  trap  dyke. 
South  of  the  dyke  the  lime  shales  at  the  top  of  the  forma- 
tion dip  S.  and  are  cut  off  by  the  great  Cornwall  fault,  their 
edges  abutting  against  the  downthrown  edges  of  the  trias. 

*  Thus  approaching  Wernersville  station  the  dip  is  10°  S.  Great  quarries 
opposite  the  station  show  the  same.  Passing  the  station  the  same  dip  ap- 
pears at  the  creek.  Approaching  Robesonia  station  the  dip  is  20°  S.  Beyond 
that  station  is  a  fine  quarry  with  dips  of  20°  S.  Here  a  branch  RR.  runs 
south  up  a  little  valley  between  highlands  to  Robesonia  furnace.  The  hill 
W.  of  the  furnace  is  perhaps  500'  high  ;  a  long  gentle  slope  of  limestone 
descending  to  the  railroad  ;  the  slope  from  the  foot  of  the  hill  to  the  railroad 
at  Womelsdorf  station  is  half  a  mile  wide;  dip  at  "the  station  5°  N.  (?); 
beyond  the  station,  30°  S.  Most  of  the  line  between  here  and  Richland 
station  is  through  slaty,  thin-bedded  limestone  beds  all  dipping  gently  S. 
but  at  one  exposure  30°. 

Slack  slates  make  a  great  show  in  the  cut  east  of  Richland  station. 
Curiously  enough  the  fields  to  the  south  expose  ribs  of  limestone  striking 
N.  and  8.;  and  in  a  second  black  slate  cut,  west  of  Richland  station,  there  is 
an  anticlinal  roll  striking  also  N.  and  &.  but  much  crushed  and  contorted. 
Further  west  dark  limestone  and  slate  dip  10°,  W.  of  S.  Still  further  on, 
approaching  Myerstown  station,  are  more  fine  cuts  in  dark  slate  dipping 
10°  south. 


310  GEOLOGICAL   SURVEY    OF   PENNSYLVANIA. 

In  spite  of  the  general  flatness  of  the  limestone  of  the 
Lebanon  plain,  there  are  plenty  of  contortions,  rolls,  steep 
dips  and  probable  overturns  in  the  quarries  around  the  city 
of  Lebanon,  and  up  to  the  south  edge  of  the  slate  belt, 
which  is  itself  greatly  compressed  and  crumpled  with  over- 
thrown south  dips. 

From  Lebanon  to  Harrisburg  S.  dips  prevail  both  in  the 
limestones  and  in  the  slates  ;  and  of  course  more  than  half 
of  them  must  be  overturns  ;  for  the  two  great  formations 
as  a  whole  are  descending  northward  to  profound  depihs 
beneath  the  Anthracite  coal  basins  of  Schuylkill  county. 
And  the  same  state  of  things  obtains  west  of  the  Susque- 
hanna  river  all  the  way  to  Maryland  and  Virginia. 

In  the  following  description  of  the  quarries  it  will  be 
noticed  that  the  southward  dips  vary  between  S.  E.  and  S. 
West.  This  shows  that  the  pressure  has  operated  in  all 
directions,  subjecting  the  stratification  to  all  kinds  of 
irregularities  ;  often  so  excessive  as  to  swing  the  dips  round 
to  east  and  west,  that  is  directly  across  the  strike  lines  of 
the  valley.  For  instance,  on  the  east  side  of  the  Schuylkill 
at  Reading,  the  dips  are  due  east,  or  towards  the  mountain 
back  of  the  city.  On  the  west  side  of  the  river  they  are  S. 
E.;  further  west  they  are  S.;  still  further  west  S.,  S.  W. 
and  sometimes  even  west.* 

That  the  south  dips  are  sometimes  normal  and  sometimes 
overturned  is  not  a  matter  of  theory.  In  Brinkley  and 
Zinn's  quarry  at  Wernersville  can  be  plainly  seen  a  fold 
thrown  over  to  the  north,  the  beds  on  both  sides  of  it  dip- 
ping 45°  S.  20°  W.  the  fold  being  tightly  compressed.  An- 
other fold,  not  quite  tightly  compressed,  but  overthrown  to 
the  N.  40°  E.  is  visible  in  Goul's  quarry,  2  m.  W.  of  Wer- 
nersville. Another  is  seen  in  Donges'  quarry  at  Myers- 
town,  Lebanon  county,  in  the  laminated  lime  slate  beds 
dipping  to  the  eastward,  the  fold  being  pushed  over  to 
the  west. 

Other  evidences  of  the  generally  folded,  compressed  and 
overthrown  condition  of  the  whole  formation  would  appear 

*  Supposing  a  N.  and  S.  fault  at  Reading,  which  is  not  probable,  the  fault 
line  4  projected  southward  would  strike  the  trap  mountain  W.  of  Birdsboro'. 


BERKS   COUNTY   QUARRIES.  311 

in  the  quarry  faces  were  it  not  that  the  excavations  usually 
follow  the  outcrop  lines  of  such  beds  as  are  of  superior 
quality,  and  seldom  cut  across  a  series  of  folded  strata. 

In  the  following  condensed  description  of  the  limestone 
quarries  of  the  Great  Valley  in  Berks,  Lebanon,  Dauphin, 
Cumberland  and  Franklin  counties,  between  Reading  on 
the  Schuylkill  river  and  Mont  Alto  near  the  Maryland  state 
line,  I  make  use  of  the  elaborate  notes  of  Mr.  E.  V.  d'lnvil- 
liers,  published  in  the  Annual  Report  of  the  Progress  of 
the  Survey  in  1886,  part  IV,  pages  1517  to  1562. 

Berks  county  quarries. 

FrilV  s  quarry,  at  the  west  end  of  the  Lebanon  Valley  RR. 
bridge  over  the  Schuylkill  river  at  Reading ;  large,  excel- 
lent for  building,  curbing,  or  paving  ;  quarry  beds  good  and 
regular  for  60';  dip  regular  40°,  S.  30°  ^.—Another,  1000' 
S.  of  bridge,  rich,  dark  blue,  good  building  stone ;  2200 
perches  per  year,  at  40  to  60  cents  a  perch  ;  dip  40°,  S.  25°  E. 

DrexeT s  quarry,  near  the  last;  occasionally  wrought ; 
beds,  V  to  4'  thick  ;  easily  quarried  and  handled ;  dip,  40°, 
S.  20°  E. 

Gudlirts  quarry,  1$  m.  W.  of  Schuylkill,  small ;  aban- 
doned ;  dip  steep,  S.  E. 

Private  quarry  of  thin  lean  beds,  3£  m.  W.  of  river  ; 
abandoned. 

DeckerV  s  quarry,  Sinking  Springs,  poor,  abandoned  ;  dip 
irregular  35°  to  50°,  say  S.  25°  E. 

Pfeifer's  quarry,  near  last,  abandoned  like  the  others 
because  the  lean  stone  is  neither  fit  for  furnace  fluxing  nor 
lime  burning.  Dip  obscure,  probably  S. 

HuyetCs  quarry,  on  the  turnpike,  1  m.  W.  of  Sinking 
Springs  ;  large,  abandoned  ;  lean,  hard,  dark  blue-gray, 
beds  alternately  thick  and  thin  (slaty),  all  dipping  30°, 
southward,  and  much  cut  up  with  cleavage  planes. 

Evans'  quarry,  on  RR.  i  m.  west  of  Columbia  Branch 
junction  (1  m.  W.  of  Sinking  Springs);  large,  old,  aban- 
doned, beds  not  pure,  dip  40°,  S. 

Ruth's  quarries  (two),  on  Columbia  branch  RR.  No.  2 
furnished  flux  for  Birdsboro'  furnaces  ;  dip  35°,  S. — No.  1 


312  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

sent  flux  to  Reading  furnace  ;  light  blue,  lean,  quite  thin- 
bedded,  dip  40°-45°,  S.  15°  E. 

Ludwig's  quarry,  S.  W.  of  last;  3  kilns;  500  bushels 
per  week  ;  home  market  at  7  cents  a  bushel ;  opposite  the 
Hat  Factory,  first  station  on  Columbia  branch  RR.  If  m. 
S.  W.  of  Sinking  Springs.  Slaty,  curly,  crushed  beds  next 
the  road,  expensive  and  irregular  to  quarry.  Elsewhere  in 
the  vicinity  beds  dip  regularly  S. 

Seltzer's  quarry,  £  m.  W.  of  last,  old  ;  beds  fairly  good, 
weathered,  broken,  irregularly  dipping  35°,  S. 

Old  quarry,  long  abandoned,  8  m.  W.  of  Reading  (near 
Wernersville),  beds  very  hard,  with  occasional  slate  part- 
ing, irregular,  dip  ?  55°,  S.  20°  E. 

Miller's  quarry,  E.  end  of  Wernersville,  300  yds.  W.  of 
last,  small  exposure  of  thin  beds,  dipping  25°,  S.  20°  W. 
(not  E.). 

BrinMey  and  Zinris  quarry,  opposite  Wernersville 
station,  once  used  by  Reading  and  Pottstown  furnaces,  now 
for  farm  lime  ;  125'xlOO',  face  25'  high  ;  beds  in  west  wall  a 
compressed  anticlinal  roll  leaning  over  to  the  north,  both 
legs  dipping  45°,  S.  20°  W.  (not  E.)  and  only  10'  of  beds, 
as  thus  doubled,  visible.* 

Whitmoyer  BroS  s  quarry  (KnoTr'  s),  near  Wernersville 
station  ;  large,  20'  high  ;  2  car  loads  a  day  to  Reading  and 
Pottstown  furnaces ;  dip  20°  to  40°,  S.  35°  W. 

Deppen's,  J.  W.  (No.  1);  an  immense  quarry  N.  W.  of 
Wernersville  ;  very  old  ;  3  kilns  ;  much  flux  also  sent  to 
furnaces  ;  stone  not  quite  good  enough  for  flux  ;  550/x300/; 
25'  face  of  beds  dipping  20°,  S.  20°  W. ;  bedding  not  es- 
pecially prominent,  and  much  of  the  stone  quite  silicious, 
pale  blue  to  grey. — (No.  2)  on  a  line  with  the  last  further 
east  and  in  the  same  beds,  9  kilns  sometimes  in  use. 

Hull' s  quarries  (two)  west  of  last,  small ;  beds  quite  con- 
glomeritic  (not  plainly  stratified,  dip  (?)  20°,  S.)  containing 
a  number  of  different  silicious  limestone  and  sandstone 

*  This  is  a  notable  instance  of  the  complicated  structure  of  the  whole  lime- 
stone belt,  and  of  great  value  to  the  geologist ;  but  it  must  be  used  with  due 
precaution  ;  for  it  may  mislead  the  student  into  the  error  of  doubting  the 
normal  south  dips  when  they  present  themselves,  as  in  the  exposures  south 
of  Lebanon. 


BERKS    COUNTY    QUARRIES.  313 

pebbles,  only  sligJitly  rounded,  and  all  firmly  cemented 
together  *— A  quarry,  £  m.  E.  of  last,  in  bluff  400'  N.  of 
pike  ;  lean,  cavernous,  pale  blue,  abandoned. 

GouTs  quarries  (three)  in  a  N.  W. — S.  E.  line  crossing 
the  RR.  3  m.  W.  of  Wernersville  (H  m.  E.  of  Robisonia); 
— (1)  just  S.  of  pike  ;  2  kilns  ;  good,  heavy  bedded,  dipping 
55°,  S.  40°  W.  in  N.  wall,  arched  over  to  a  less  sleep  S.  40° 
W.  dip.-f—(2)  S.  of  RR.  (11  m.  W.  of  Reading);  disused  ; 
moulh  of  cave;  dip  30°,  S.  40°  W.J— (3)  S.  E.  of  last,  small, 
1  kiln. 

Two  small  farm  quarries,  £  m.  N.  W.  and  in  line  with  the 
three  Goul  quarries  show  dips  of  40°,  nearly  due  S.  and 
40°,  S.  15°  W.§ 

Wenrich's  (W.)  quarry  on  the  hill  slope  S.  of  RR.  1  m. 
S.  E.  of  Robisonia  station  ;  small ;  dip  40°,  S.  15°  W.— 
WenricKs  (A.\  %  m.  N.  of  the  station  ;  35°,  S.  20°  W. 

Deppen's  (Sam.}  S.  of  RR.  £  m.  W.  of  Robisonia  sta- 
tion ;  2  kilns,  35,000  bushels  per  annum  ;  some  building 
stone  sold,  but  beds  thin  and  broken  ;  dip  20°,  S.  20°  W. 

A  quarry,  on  the  RR.  H  ni-  west  of  Robisonia  station  ; 
small ;  important  as  showing  a  dip  of  85°,  S.  W. — Another 
\  m.  W.  of  it,  just  N.  E.  of  AVomelsdorf  station,  worked 
for  RR.  ballast,  dips  60°,  S.|| 

Moore1  s  quarry,  on  RR.  1  m.  W.  of  last,  and  S.  W.  of 
Womelsdorf ;  small ;  much  earth  to  strip ;  beds  £'  to  !£' 

*  These  conglomerates  are  among  the  strangest  phenomena  of  the  forma- 
tion No.  II,  and  very  hard  to  explain.  Were  it  not  for  the  sandstone  peb- 
bles, they  might  all  be  taken  for  breccias,  or  crushed  limestone  beds 
cemented. 

fHere  then  is  another  evident  compressed,  overthrown  anticlinal,  not 
quite  transverse  to  the  strike  of  the  belt,  but  very  oblique  to  it. 

I  The  stone  here  is  reported  quite  manganesian.  This  shows  that  we  are 
in  the  lower  division  of  the  formation  (Ha);  and  the  sum  total  of  dips 
southward  must  be  interpreted  and  calculated  with  this  fact  in  view. 

§  This  only  emphasizes  the  general  rule  of  the  whole  limestone  belt,  that 
the  strike  lines  are  all  local,  and  cannot  be  followed  for  even  half  a  mile. 
In  other  words  the  irregularity  of  limestone  strikes  is  as  great  and  universal 
as  that  of  dips.  The  compression  of  the  formation  was  equal  in  all  direc- 
tions vertical  and  horizontal.  The  structure  could  not  exhibit  these  features 
had  the  movement  not  been  effected  under  the  enormous  weight  of  the 
higher  Palaeozoic  formations. 

||  These  are  instances  of  very  high  dips  which  help  to  give  credence  to  the 
overturned  anticlinal  exposures. 


314  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

thick  ;  very  dark  blue,  medium  quality  for  flux  ;  good  for 
ordinary  building  ;  dip,  35*,  S.  10°  W. 

Lebanon  county  quarries. 

Gehref  s  quarry,  on  RR.  near  county  line,  W.  side  of 
steep  hill,  E.  of  Sheridan  furnace,  small,  fair  building  stone. 
— EckerV  s,  small  quarry  N. . of  RR.  W.  of  Sheridan  sta- 
tion.— Kauffman  &  CoS's,  £  m  S.  of  Sheridan  station,  once 
worked  for  flux,  lean  and  slaty  and  abandoned  for  the  Ann- 
ville  stone  now  in  use. 

Kauffman  &  Co.'s  large  abandoned  quarry,  just  S.  W. 
of  Richland,  slaty  beds,  dipping  25°,  S.  15°  W.  round  to 
due  W.* — Shaffer  &  YingsC  s  small  pits,  in  hard,  silicious, 
irregularly  disturbed  beds. — Landls1  quarry,  on  RR.  at 
Richland  ;  old  ;  all  stone  (when  quarried)  sent  to  Tamaqua, 
Schuylkill  conuty,  lime  kilns  ;  quality  fair  ;  beds  of  variable 
thickness,  broken,  dipping  15°  to  20°,  S.  25°  W.— Loose's 
two  small  quarries,  £  m.  W.  of  last,  75'  long,  20'  high  ;  dip 
15°,  S.  W. 

HartlieV  s  quarry,  on  RR.  2  m.  W.  of  Richland,  1£  m. 
E.  of  Myerstown  ;  stone  admirable  for  curbing,  paving 
and  light  building ;  light  covering;  dip  10°  to  15°,  S.  10° 
to  20°  W.—Jtoyer's,  near  last ;  300'  long  along  RR.,  20' 
high,  beds  £'  to  3'  thick,  uniformly  good  for  building  and 
curbing  ;  dip  10°,  S. 

Myerstown,  three  quarries  on  the  canal,  by  which  their 
stone  is  shipped  to  Reading  for  plastering  walls  : — Miller, 
«/!,  in  thinly  laminated  slaty  beds  dipping  S.  E.  (not  S.  W.) 
—Miller,  /.,  dip,  20°,  S.  10°  E.—Donaes\  250' long,  22' high 
in  N.  face,  which  shows  a  small  anticlinal  arch,  dipping 
20°  to  35,  east  (not  south,  or  S.  E.)beds  thinly  laminated, 
with  some  slaty  impure  layers ;  2  kilns  of  300  bushels 
capacity  each.f 

Sassier  quarry,  1  m.  W.  of  Myerstown,  £  m.  N.  of  RR. ; 
35  years  old ;  2  kilns  of  350  and  400  bushels  capacity ; 

*Here  is  a  specimen  of  the  universal  warped  structure  of  the  whole  belt, 
full  as  it  is  of  innumerable  small  short  dying  anticlinals  around  the  ends  of 
which  the  strike  lines  swing  sharply,  and  throw  the  dips  off  fanwise. 

f  Here  we  have  both  anticlinal  and  transverse  dips. 


LEBANON    QUARRIES.  315 

45,000  bush,  have  been  burned  here  in  one  year  all  for  farm 
use  at  8  cents  per  bushel  ;  in  1886  only  4,500 ;  250'  long  N. 
and  S.  by  150'  E.  and  W.  by  20'  high ;  dip  in  W.  wall  32°, 
S.  22°  E.  in  N.  wall  45°;  in  E.  wall  still  steeper. 

UricKs  ( Vol.}  quarry,  £  m.  W.  of  last,  £  m.  N.  of  RR., 
semicular,  70'  long,  18'  face  ;  2  kilns ;  3,000  bush,  per  sea- 
son for  farm  use  ;  beds  good,  hard ;  J'  to  2f  thick,  easily 
quarried  ;  produces  some  of  the  best  building  stone  in  the 
whole  Lebanon  Valley;  much  of  it  used  for  building;  2 
horse  load  sold  for  75  cents,  (1  perch  measured  in  the  wall) 
if  the  purchaser  loads  and  hauls  his  own  stone.  Dip,  55°, 
S.  15°  E. 

Urictts  (S.)  \  m.  W.  of  last,  on  canal,  very  long  rambling 
quarry.  200'  wide  near  E.  end  ;  one  pit  at  the  lock,  100'x- 
50'xlo'  deep  ;  dip  here  60°,  S.  20°  E.;  in  N".  face  57°,  S.  25° 
E. ;  in  next  pit  55°,  S.  15°  E. ;  stripping  uniform  and  rather 
heavy  ;  stone  good  flux  shipped  east. 

Beckley 's,  1  m.  S.  W.  of  last,  |  m.  S.  E.  of  Prescott  sta- 
tion, small,  1  kiln  of  250  bush,  drawing  80  bush,  per  day  ; 
quarrying  costs  5  c.  per  100  bushels  ;  lime  sold  to  farms  at 
8  c.  per  bush.;  ballast  delivered  on  RR.  track  for  $1  per 
one-horse  load.  N.  B.  this  is  the  last  quarry  until  the 
Lebanon  quarries  are  reached,  four  miles  further  west. 

Lebanon  city  group. 

At  Lebanon,  on  the  east  side  of  the  city  is  a  line  of 
quarries  extending  N.  and  S.  viz.:  Horst's  &  Fritz's  N.  of 

the  RR.,  Shenk  &  Herr's,  Wagner's,  Houck's, , 

March's  and  Coleman  heirs',  S.  of  the  RR.  On  the  west 
side  of  the  city  are:  Brock  Bro.'s,  N.  of  the  RR.  and 
Meily  &  Brother's,  Groninger's,  Coleman  heirs'  and  Horst's. 

Horst  quarry,  very  old,  150'x250'x40'  deep ;  2  kilns, 
drawing  each  125  bushels  daily;  yearly  output  35,000 
bushels,  worth  12  to  15  c.  picked  lime  delivered,  4  c.  slaked, 
used  chiefly  for  mortar  and  plaster  ;  beds  1'  to  2£';  dip  35°, 
westward,  in  some  parts  swinging  round  to  the  south. — In 
a  brick  yard  quarry,  1000'  E.  of  last,  the  limestone  beds 
dip  35°,  S.  25°  W.— Fritz's  quarry,  abandoned;  2  kilns 
(supplied  from  Wagner's  quarry);  bluegrey  beds,  withou 


316  GEOLOGICAL   SURVEY    OF   PENNSYLVANIA. 

regular  dip :  cleavage  planes  70°,  towards  W. ;  275'  long, 
20'  deep,  stripping  heavy. 

STierik  and  Herr' s  ;  old  ;  2  kilns  ;  120'x75'x20'  deep,  dip 
on  W.  side  15°,  westward  ;  on  E.  side  55°,  southward.* 

Wagner' s;  %  m.  S.  of  last ;  160'xlOO'x20';  beds  massive, 
used  largely  for  Lebanon  city  buildings  ;  dip  35°,  S.  30°  E. 

HoucJc's,  S.  end  of  city  ;  100'x20';  good  bluegray  beds, 
dipping  35°,  S.  30°  E. — Another,  near  it,  exclusively  for 
building  stone,  250',  E.  and  W.  20'  high  ;  dip  20°-30°,  S.  E. 
(This  stone  is  finely  laminated.} — March's,  near  the  last, 
and  on  the  Cornwall  and  Lebanon  RR.  175'  N.  and  S.  35' 
deep  ;  flux  and  building  stone  ;  dip  20°,  S.  50°  E.f 

Coleman  heirs',  two,  immense  quarries,  old,  abandoned, 
together  1000'  long,  along  the  RR.,  formerly  fluxing 
Cornwall  andDonaghmore  furnaces,  but  too  hard  and  lean  ; 
N.  quarry  beds  all  dip  35°,  S. ;  S.  quarry  32'  wide,  35'  deep, 
dip  35°  to  50°,  S. 

Brock  Brothers'  quarry  exclusively  worked  for  the  N. 
Lebanon  furnaces,  on  the  old  canal ;  400'x500'x40'  deep  ; 
steam  drills,  etc.,  in  use  ;  35'  of  beds  (!'  to  4'  thick)  dip 
20°,  S.  20°  W.;  in  places  wavy;  but  in  S.  and  E.  sides 
strata  even  beds  and  regular  dip  ;  the  stone  is  light  gray  to 
pronounced  blue  and  of  superior  quality,  but  not  quite  so 
non-siliceous  as  the  Annville  stone. 

Meily  &  Brother,  just  S.  of  their  Lebanon  furnaces,  S.  of 
RR. ;  started  1868  ;  in  1886  400'xlOO'x30'  deep  ;  very 
handsome  face,  especially  along  the  north  side  of  main  cut. 
and  dipping  gently  15°,  toward  S.  W.;  stripping  heavy; 
massive  stone  can  be  quarried  through  the  larger  part  of 
the  uncovered  area  ;  stone  blue-gray,  somewhat  lighter  than 
Annville  stone  ;  beds  thin  and  massive  (!'  to  3')  quite  free 
from  silicious  matter  /  quarry  contracts,  30  c.  a  ton  ;  1200 
tons  of  flux  per  month. 

Gloninger  estate,  small,  1  m.  W.  of  Lebanon  center,  on 
Quittapahilla  creek,  2  kilns,  each  draws  200  b.  per  day  ; 
12£  c.  picked,  6  c.  per  bushel  run  of  the  kiln  ;  local  mar- 
ket ;  dip,  25°  to  45°,  S. 

*  Another  case  of  rapidly  changing  dip  ;  or  warp. 

f  Here  we  have  one  of  the  very  highly  diagonal  strike  lines. 


ANNVILLK   QUARRIES.  317 

Coleman  heirs*,  near  Donaghmore  furnace ;  hillside 
quarry  ;  dips  S. 

Coleman' s  quarry,  on  RR.  just  W.  of  Colebrooke  fur- 
naces, 2m.  W.  of  Lebanon  city;  enormous  excavations; 
output  of  flux  for  the  Colebrooke  furnaces  very  great ; 
steam  drills,  etc.;  all  the  strata  good,  lie  very  flat,  but  gen- 
erally dip  gently  southward.* 

The  Annville  group. 

Annville  is  4f  miles  W.  of  Lebanon  city. — Kr eider's 
quarry  is  3  miles  W.  of  Lebanon,  on  the  RR.  If  m.  E.  of 
Annville  ;  started  1885  ;  100'x90'x20';  exclusively  for  flux, 
15  small  car  loads  per  day  ;  strata  vary  ;  30'  of  good  blue 
stone;  stripping  heavy;  dip  of  S.  face  12°,  S.  10°  W.,  of 
W.  face  15°-20°,  S.  60°  W.—  Yoke's,  \\  m.  E.  of  Annville, 
small,  2  kilns. — Kreider 's,  £  m.  E.  of  Annville  ;  good  stone, 
dips  steep  S. 

Light  and  ffouser's  quarry'  just  W.  of  Annville  ;  stone 
deep  blue,  excellent ;  stripping  heavy  ;  long  cut  in  hill- 
side to  reach  best  stone  in  S.  end,  where  75'  wall,  20'  high  ; 
cleavage  prominent  (with  slips  75°,  N.  80°  E.)  dip  25°,  W. 
and  25°,  S.  10°  W. 

Beaver's  quarry,  just  W.  of  last,  on  same  S.  side  of 
creek  ;  old,  large,  600'x800',  back  from  creek  to  pike  ;  dip 
everywhere  gently  S.  E.  and  S.  W.;  small  roll,  one-half 
of  saddle  exposed,  with  35°  dip,  diminishing  rapidly  to  10° 
at  the  pike.  Farm  lime  and  chemical  lime,  and  much  fur- 
nace flux  (80  tons  a  day  to  Sheridan  and  Topton).  In  1886, 
1,000  bush,  lime  a  month  went  to  C.  Warner  &  Co.'s  paper 
works  at  Wilmington,  Del.  Five  draw  kilns,  6'x26',  150 
bu.  per  kiln,  four  always  in  action.  Cost  of  quarrying, 
breaking  and  delivering  at  kiln,  85  c.  per  100  bushels,  pow- 
der and  tools  furnished  to  contractor.  Fhix  stone  sold  on 
cars  at  quarry  for  41  c.  'per  ton.  Analysis  96  to  98  per 

*Here  is  a  typical  case  of  undistured  localities  in  the  great  belt,  which 
have  escaped  the  otherwise  ubiquitous  pressure-crumpling.  The  belt  is  here 
nearly  at  its  widest,  and  the  quarry  is  not  far  from  the  edge  of  the  slate  belt 
to  the  north  of  it  Consequently  the  purer  beds  of  the  upper  or  Trenton 
division  (77c)  of  the  great  formation  are  here  quarried. 


318  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

cent.  carb.  lime. — Light  and  Housed  s,  small,  new  in  1886. 
— Messner's,  old,  abandoned. 

Kauffman  &  Co?  s  two  quarries  ;  one  on  RR.  250'  from 
creek  ;  beds  V  to  !£',  very  regular  and  uniform,  25°  to  30°, 
S.  10°  W.— The  other  S.  of  it,  150'  wide,  20'  deep ;  stone 
finely  laminated,  dips  20°,  S.  40°  E.  (sometimes  swinging 
to  S.  W.);  beds  not  massive,  nor  thick,  and  more  gray  than 
the  other  Annville  stone  ;  output  of  both  quarries  3000  to 
4000  tons  per  month  to  Sheridan  and  Reading  furnaces. 

Brightbill  &  Sorts  two  very  large  quarries  on  RR.  If  m. 
W.  of  Annville  ;  one  500'  long ;  50'  of  rock  exposed  ;  ex- 
cellent, fine-grained,  soft,  brittle,  blue-gray,  thin  beds, 
wavy  on  W.  side,  regular  (on  E.  side)  dip  60°-70°,  S.  40° 
E.  Crush  in  S.  face. 

Kr  eider's  quarry  just  west  of  last ;  5  kilns,  output  5500 
bush,  per  month  shipped  to  Powers  &  Weightman's 
chemical  works  in  Philadelphia,  and  to  Pa.  Salt  Co.  Always 
in  high  repute  for  chemical  and  other  special  uses,  and 
flux ;  100  bush,  lime  from  6£  tons  stone  and  17CO  Ibs.  coal 
(best  record);  output  of  flux  stone  1000  tons  per  month,  at 
31  c.  per  ton  on  car.  Quarry  250'xl75';  10'  to  30'  deep  ;  dip, 
12°  to  45°,  S.  E. 

Batdorff  &  Beaver's,  next  west  in  the  line;  300'  long, 
irregular  shape,  40'  to  50'  face  in  places  ;  inexhaustible 
quantity  of  first-class  limestone;  output  2300  tons  per 
month  ;  best  stone  from  center  of  quarry  ;  blue,  soft,  %50' 
thickness  of  beds  suitable  for  the  market ;  dipping  uni- 
formly, 40°  to  70°,  both  to  S.  E.  and  S.  W.* 

ShenJc  BroSs  old  quarries,  |  m.  W.  of  last,  small,  aban- 
doned, 10'  face,  dip  65°  (?)  S. 

Oruber  &  Bowman  pits  and  kilns  at  Palmyra,  near  the 
Dauphin  county  line,  furnish  good  building  stone,  and  farm 
lime.  Their  beds  have  no  geological  connection  with  the 
Annville  beds  (3  miles  E.  of  them)  and  are  out  of  line  with 

*There  are  slaty  layers  in  this  quarry  which  do  not  appear  in  Kreider's 
quarry  probably  because  they  run  past  the  Kreider  quarry  to  the  south  of 
it.  It  is  a  task  for  a  future  survey  to  clear  up  the  geology  of  this  important 
line  of  beds  ;  to  determine  whether  these  dips  are  overthrown  or  not ;  to  fix 
their  place  in  the  column  of  II  a,  6,  c ;  and  to  reveal  their  connection  with 
the  slate  belt  III  a,  &,  to  the  north  of  them. 


DAUPHIN    COUNTY    QUARRIES.  319 

them  far  to  the  south,  but  in  line  with  the  first  quarries  in 
Dauphin  county  next  to  be  described. 

Dauphin  county  quarries. 

Shenk  (Ab.)  quarry,  1000'  S.  of  RR.  1  m.  W.  of  Palmyra 
station,  in  horizontal  strata*  peculiarly  adapted  for  build- 
ings, in  layers  from  9"  to  2',  sold  at  the  quarry  for  60-65  c. 
on  cars  at  RR.  station  for  90-95  c.  per  perch. — Barber's 
(JR.  RR.)%m.  W.  of  last,  on  S.  side  of  RR.;  old  ;  dip  10°,  S. 

Landis  quarry,  £  m.  N.  of  RR.,  £  m.  W.  of  Lebanon 
county  line  and  £  m.  N.  W.  of  Shenk  quarry  ;  superior 
quality  of  bedsf  (Trenton?);  6  kilns,  for  farm  use  from 
1856  to  1881,  since  then  for  building  and  plastering  also  ; 
SCO'  long  N.  and  S.  50'  wide,  30'  face,  dip  35°  to  40°  S.  20° 
E. — Gingrich's  quarry  near  and  south  of  last ;  face  25';  dip 
25°  to  35°,  S.  30° ~E.—  HoJce's,  near  last,  abandoned,  dip  60°, 
S.  25°  E. 

Mayer's  abandoned  quarry  just  S.  of  Derry  station,  on 
steep  bluff  facing  Spring  creek ;  beds  £'  to  3£'  thick,  dip 
50°,  S.  60°  ^.—Hershey  quarry,  near  and  E.  of  last ;  build- 
ing stone  for  new  Derry  church  ;  50/x25/,  18'  face,  dip  12° 
to  20°,  S.  E. 

Swatara  quarries. 

Kavffman  &  Co.,  abandoned,  300'  long,  face  20',  dip  S. 
E. — Landis  quarry,  facing  last  on  W.  and  Zimmerman 
quarry  its  continuation  north.:}:  Landis  kilns  (3)  put  out 
2800  bush,  lime  per  week.§  Dip  of  S.  end  of  Landis  quarry 
45°,  S.  E. — Zimmerman  quarry  makes  a  fine  display  of 

*  Perhaps  with  the  slightest  possible  slope  S.  E. 

t  Rock  grey- blue  ;  output  6000,  7000  bush,  per  month,  all  sold  in  Philadel- 
phia and  New  York  for  paper,  glassware,  sugar  refining,  medicine,  as  well 
as  building,  large  wagons  holding  85  to  90  bush.  (80  Ib.  to  bush.)  take  it  to 
Palmyra  station  ;  hauling  $1.75  per  100  bushels;  kilns,  6x18x20,  consume  \\ 
tons  pea  coal  to  100  bush,  lime  ;  drawn  twice  a  day. 

J  There  are  only  26'  of  interval  strata  between  the  top  Zimmerman  bed 
and  the  bottom  Landis  bed  ;  but  the  strata  are  crushed  and  folded,  hard  to 
read,  and  expensive  to  work.  The  deep  blue  massive  Landis  N.  beds  can 
be  faintly  identified  with  the  S.  Zimmerman  beds. 

§See  statistics  of  hands,  powder,  etc.,  etc.,  in  An.  Rt  1886,  part  IV,  p.  1535, 
by  d'Invilliers. 


320  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

good  stone  for  lime  ;  60'  of  beds  exposed  dipping  20°  to  25°, 
S.  E.*  Output  13,000  bush,  of  farm  lime  per  year. 

Union  Deposit  Furnace  Co.s"1  large  quarry  just  N.  W. 
of  Swatara  station,  E.  side  of  branch  RR.  to  furnace  ;  200' 
(N.  &  S.)  long,  35'  working  face,  displaying  WO'  of  suc- 
cessive beds  all  dipping  60°,  S.  35°  E.;  lower  beds.(N.  end) 
somewhat  slaty  ;  center  beds  handsome  blue  stone  (like  the 
Annville  stone  only  rather  more  massy  V  to  3'  thick);  best 
center  beds  measure  25';  upper  (S.)  beds  broken  by  cleavage, 
not  so  pure,  harder  to  quarry. 

Erb's  quarry,  \  m.  N.  of  Swatara  station,  N.  side  of 
Spring  creek  ;  125'  (N.  &  S.)  22'  high  ;  tightly  folded  beds, 
dipping  E.  (?),  3  kilns  for  local  market. 

Ginrlch 's  three  quarries  f  m.  N.  W.  of  Swatara  station, 
S.  of  Swatara  creek,  close  to  the  edge  of  the  slate  belt  (Hudson 
River  Slate,  No.  111.)— (a)  180'  long,  20'  face,  dip  at  E.  end 
45,°  S.  25°  E.;  at  W.  end  the  same  -but  more  massive  ;  — (b) 
125'  long,  28'  face,  beds  wavy,  dip  irregular  ; — (c)  175'  long, 
20'  face.  Average  stripping  (on  all)  5' ;  beds  1'  to  4'  thick, 
each  layer  very  uniform,  f 

Hummelstown  group. 

Garman's,  1  m.  E.  of  Hummelstown;  long  disused  100' 
long,  20'  face  :  beds  hard  and  slaty,  dipping  30°,  S.  60°  E. 
(i  m.  E.  on  RR.  there  is  a  dip  of  45°,  E.  S.  E.) 

Hershey1  s  three  small  quarries,  £  m.  E.  of  Hummelstown, 
on  branch  RR.  to  Walton's  Brownstone  (Trias)  quarries;—- 
(a)  75'  long,  15'  high  against  steep  W.  hillside,  in  beds  slaty 
and  finely  laminated,  dipping  25°,  S.  40°  E;  (b)  on  level, 
older,  40'  diameter ; — (c)  at  limekilns,  small.  Analysis 
(claimed)  97  to  98  p.  c.  carb.  lime.  Building  stone  sent  to 

*  Thickest  beds  3  ;  much  good  building  stone  could  be  obtained  here,  the 
stratification  is  so  regular ;  breaking  in  rectangular  blocks. 

t  The  fifteen  quarries  just  described  (Palmyra,  Berry,  Swatara  groups) 
work  a  belt  of  upper  (Trenton  ?)  limestones  next  to  the  slate  belt,  under 
which  they  should  descend.  And  yet  all  the  dips  are  S.  S.  E.  away  from 
the  slate  belt.  This  parallelism  with  the  slate  belt  edge  precludes  the 
notion  of  nonconformability ;  therefore  there  must  either  be  an  upthrow 
fault ;  or  all  the  limestone  beds  must  be  overthrown  and  therefore  reversed, 
the  lower  beds  lying  upon  the  upper. 


DAUPHIN    CO.    QUARRIES.  321 

Harrisburg  builders,  and  Reading  bridge  work.*     Dip  in 
all  three  S.  &  S.  E. 

Holler's^  at  Hummelstown.  between  RR  and  Swatara 
river  ;  250'xl25'x25'  face  ;  beds  4"  to  3',  dipping  uniformly 
23°,  S.  10°  E.;  stripping  averages  3';  sold  for  building;  4 
kilns,  output  40,000  bush,  per  year.— Rutherford's,  \  m. 
W.  of  last,  on  N.  bank  of  river ;  200',  narrow,  20'  face, 
building  stone  like  last ;  dip  20°  to  30°,  S.  40°  *&.— Eagle's, 
on  turnpike  at  bridge,  f  m.  W.  of  Hummelstown  ;  small, 
for  local  farm  lime  ;  dip  obscure,  gently  S. 

Beaver  station  group. 

Allweiris  quarry,  300  yds.  E.  of  Beaver  station  (175  yds. 
N.  of  RR.)  on  the  edge  of  the  slate  belt;  200'  long  (on  N. 
side  of  steep  bluff),  25'  face  ;  dips  observed  30°,  S.  and  60°, 
S.  23°  W.  showing  much  warping,  f 

Webner's  quarry,  abandoned  near  RR.  E.  of  Beaver 
station;  beds  thin,  S.  dip. — Rutherford's  quarry  just  W.  of 
station  ;  150'xlSO';  30'  N.  wall ;  dip  in  N.  wall  30°  S.  becom- 
ing quite  flat  southward  along  E.  and  TF.  walls. 4  Some 
beds  large  and  massive  building  stone  ;  2  kilns,  20,000  bush, 
farm  lime  per  year. — CasseV  s  quarry,  long  abandoned,  mid- 
way between  Beaver  and  Rutherford  stations. 

*  None  of  the  layers  exceed  4',  but  there  is  little  cleavage. 

f  A.  very  Interesting  locality,  being  near  the  east  point  of  a  long  narrow 
belt  of  limestone  enclosed  between  the  great  slate  belt  on  the  north  and  an 
isolated  branch  of  it  running  from  it  S.  W.  and  W.  to  the  Susquehanna  below 
Harrisburg.  The  limestone  belt  must  be  anticlinal ;  and  the  slate  branch 
belt  synclinal.  On  the  RR.  near  Beaver,  limestone  dips  20°,  S.  E.  towards 
the  southern  slate ;  so  also  20°,  S.  dips  are  to  be  found  along  the  south  edge 
of  the  limestone  belt  one  and  two  miles  from  the  river.  On  the  RR.  ap- 
proaching the  Susquehanna  limestone  N.  dips  are  seen,  as  if  going  under  the 
great  slate  belt  edge  to  the  N.  But  generally — almost  universally — the  lime- 
stones dip  S.  at  various  angles,  as  will  be  shown  in  the  description  of  the 
quarries  between  Beaver  and  Harrisburg.  Of  course  the  30°  and  60°  S.  dips 
in  the  text  above  must  be  overturned  N.  dips.  What  makes  this  more 
striking  are  slate  dips  of  35°  and  32°  S.  within  a  mile  E.  N.  E.  of  Beaver. 
These  and  also,  58°,  40°,  60°,  70°  S.  dips  in  the  slate  belt  a  mile  and  more 
north  of  Beaver,  must  be  all  or  most  of  them  overturns. 

t  This  would  make  an  overturn  of  the  30°  dip  an  impossibility  ;  and  an 
anticlinal  between  the  quarry  and  the  slate  edge  on  the  north  a  necessity, 
unless  an  upthrow  fault  be  made  to  run  the  7  miles  from  Beaver  to  Harris- 
burg. 

21 


322  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

Paxtang  group. 

Metes  quarries  E.  of  Paxtang  station. — (a)  150  yds.  N.  of 
RR.  250'  E.  &  W.  20'  to  25'  face ;  hard,  thick,  building 
stone  beds,  dip  in  S.  face  55°,  S.  20°  W.;  in  E.  face  35,  due 
S.;  4  kilns.— (b)  50  yds.  N.  of  last,  100'xlOO'x25';  dip  wavy, 
25°  to  35°  S.  W.— (c)  N.  of  RR.  £m.  E.  of  station  ;  regular 
•beds,  1'  to  2|'  thick,  dipping  25°,  S.  5°  W.— (d)  S.  of  RR. 
near  last ;  beds  of  pale  blue,  or  bluish  grey  inclined  to  be 
cavernous,  6"  to  2'  thick ;  output  60,000  bush,  in  a  single 
year  (3  kilns).* —  WilJielm? s  quarry  a  little  north  of  (c),  beds 
V  to  3',  dip  20°,  S.  15°  E. 

Rutherford? s  (J.  A.)  \  m.  S.  E.  of  station,  (3  m.  E.  of 
Harrisburg)  worked  in  1884  for  fluxing  McCormick  &  Go's 
Paxton  furnaces  ;  large  N.  E. — S.  W.  opening  each  side  of 
Spring  creek  ;  beds  very  fine  grained  ;  so  much  cleft  as  to 
obscure  the  dip,  which  is  S.  S.  E.  in  40'  of  beds,  S.  end. 

Rutherford  estate  quarry  J  m.  S.  of  station  S.  side  of 
Spring  creek  ;  2  kilns,  best  lime  hauled  to  Harrisburg  where 
it  brings  16c.  per  bushel ;  local  farm  lime,  7c. ;  2240  Ibs. 
coal  to  100  bush,  lime ;  30'  face  of  good  grey-blue  strata, 
dipping  40°,  S.  15°  E.  (cleavage  55°,  N.  15°  W.). 

Rutherford  No.  0,  N.  of  RR.  close  to  station ;  200',  E. 
and  W. ;  long  abandoned  ;  beds  hard,  siliceous,  like  or  per- 
haps the  same  as  the  beds  in  the  RR.  cuts  towards  Harris- 
burg. f 

McCormick' s  quarry,  on  RR.  f  m.  W.  of  Paxtang  station 
and  2  m.  E.  of  Harrisburg;  400'  long  (S.  W.);  best  stone 
now  got  at  S.  end  ;  good,  pure,  smooth-grained,  gray  lime- 
stone, very  low  in  silica,  and  easily  quarried ;  beds  2'  to  4' 
thick  ;  40'  face  ;  dip  generally  S.  E.  but  a  small  synclinal 
and  anticlinal  roll  near  center  of  quarry  close  to  a  clay 
seam  (fault  f}^.  Output  of  flux  for  Paxton  furnaces  at 
Harrisburg  165  cars  of  16  tons  each  per  month  ;  quarry 

*  See  statistics  of  work,  cost,  etc.,  in  An.  Rt.  1886,  IV,  p.  1527. 

f  No  dip  is  given  by  D'Invilliers;  but  on  Sander's  dip  map  of  Dauphin  a 
N.  dip  is  here  marked  ;  which,  if  true,  is  important. 

f  It  seems  as  if  the  change  from  the  northern  4  to  12  p.  c.  siliceous  beds  to 
the  southern  non-siliceous  beds  took  place  at  the  clay  seam  ;  the  color  cer- 
tainly changes  there,  the  siliceous  beds  being  a  medium  blue. 


DAUPHIN    CO.    QUARRIES.  323 

started  April,  1886;  steam-drill  (2"  diam.)  drills  80'  per 
day. — An  old  quarry,  300'  E.  of  last,  shows  a  synclinal 
with  gentle  dips  on  S.  side  and  70°,  S.  30°  E.  on  N.  side.* 
Wister  BroSs  quarry,  on  RE.  If  m.  E.  of  Harrisburg ; 
stripping  8'  over  30'  beds  (6"  to  3£"),  of  good  quality,  mostly 
massive,  full  of  cleavage  planes  ;  dips  at  both  ends  42°-52°, 
S.  10°  E. 

Great  quarries  are  seen  in  the  hills  facing  the  Susque- 
hanna  south  of  Harrisburg,  furnishing  flux  to  the  iron 
works. 

*  Precisely  the  reverse  of  what  we  should  expect ;  even  an  upthrow  fault 
north  of  it  would  not  furnish  a  probable  explanation,  for  such  a  fault  would 
have  a  N.  dipping  brush  on  its  southern  side.  We  must  take  this,  like  so 
many  other  structural  features  of  the  limestone  belt,  as  an  exhibition  of  the 
infinitely  irregular  effects  of  the  general  movement-pressure.  The  common 
diagonalism  of  these  dips  to  the  straight  course  of  these  anticlinal  limestone 
belts  is  very  remarkable  and  hard  to  explain. 


324  GEOLOGICAL    SURVEY    OF    PENNSYLVANIA. 


CHAPTER  XXVII. 

Limestone  quarries  of  the  Or  eat  Valley  west  of  the  Sus- 
quehanna,  and  in  Mountain  Creek  valley. 

Cumberland  county  quarries. 

Opposite  Harrisburg  there  is  a  continuous  exposure  of 
upturned  limestone  beds  in  the  Susquehanna  right  bank, 
and  in  the  railroad  cuts,  from  Bridgeport  down  (south)  to 
New  Cumberland,  a  distance  of  two  miles  ;  this  being  the 
width  of  the  Beaver-Rutherford-Paxtang  limestone  belt  (of 
the  quarries  last  described)  where  it  crosses  the  river  at  and 
below  Harrisburg.  The  belt  is  enclosed  between  the  great 
slate  belt  on  the  north,  and  an  outlying  synclinal  slate  belt 
on  the  south  ;  as  shown  on  the  colored  geological  map  of 
Cumberland  county.* 

All  the  exposures  of  limestone  for  the  whole  width  of  the 
belt  show  south  dips  ;  and  yet  the  belt  ought  to  be  anticli- 
nal, with  south  dips  at  New  Cumberland  and  north  dips  at 
Bridgeport.  Consequently  the  south  dips  at  Bridgeport 
must  be  overturned  north  dips  ;  but  the  overturn  is  so  ex- 
treme that  the  beds  dip  only  30°,  with  great  regularity  and 
perfect  conformability  along  the  whole  face  of  the  great 
quarries  of  McCormick  &  Co.,  beginning  at  the  limekiln 
south  of  the  west  end  of  the  Harrisburg  bridge.  The  low- 
est beds  at  the  limekiln  must  therefore  be  geologically  the 
top  beds  of  so  much  of  the  series  as  is  exposed  in  the  quar- 
ries ;  and  the  slates  at  the  bridge  instead  of  overlying  them 
must  descend  southward  beneath  them.f 

*  Published  in  Atlas  to  D5,  with  Franklin  and  Adams  county  maps,  etc. 

t  It  is  impossible  to  construct  the  curve  of  such  a  gigantic  collapsed  over- 
turned anticlinal  without  imagining  a  slip  fault  on  the  north  side  of  it, 
either  in  the  limestone  or  in  the  slate,  or  between  the  two.  There  is  no 
sharp  distinction  between  the  limestone  and  slate  formations;  the  limestone 
grows  shaly  upward  and  gradually  merges  into  the  shales;  and  this  is  well 
shown  by  Mr.  B.  S.  Lyman's  field  sections  of  the  passage  rocks  between  II 


CUMBERLAND    COUNTY    QUARRIES.  ,       325 

McCormick  &  Go's  (old  Walton)  quarry,  about  £  m.  S.  of 
the  RR;  bridge,  exposes  along  the  N.  C.  RR.  about  400'  of 
strata  dipping  25°  to  30°,  S. ;  varying  in  thickness  from  2 
inches  to  12  feet  solid  ;  and  in  quality  from  a  nearly  pure 
limestone,  with  but  1  or  2  per  cent  of  magnesia,  to  a  nearly 
typical  dolemite  with  35  or  40  per  cent  of  magnesia.* 

Williams'  quarry,  on  Yellow  Breeches  creek,  10  m.  S. 
W.  of  Harrisburg,  at  the  junction  of  the  Dillsburg  Branch 
and  H.  &  P.  RRs. ;  purer  blue  limestone  20',  overlaid  by 
less  pure  greyish  white  20',  dipping  12°  to  15°,  S.  E.  good 
strong  lime  for  local  market. 

Boiling  Springs  quarry,  5  m.  higher  up  the  creek,  west; 
60'  face  of  blue  limestone  with  smooth  grain,  in  plates  6" 
to  18"  thick,  dipping  20°  to  30°,  due  E.  Furnishes  flux  to 
Katharine  furnace. 

Woods',  and  other  smaller  quarries  between  Carlisle  and 
Mt.  Holly,  on  the  Gettysburg  &  Harrisburg  RR.  furnish 
farm  lime  for  local  market. 

Pine  Grove  quarry  on  Mountain  creek,  7  m.  above  Mt. 
Holly  Springs,  in  the  heart  of  the  South  Mountains,  near 

and  111  in  the  horse-shoe  bends  of  the  Conedogwinet creek  north  of  Hoges- 
town,  Kingston  and  Middlesex  a  few  miles  further  west.  Therefore  there 
is  no  mode  of  exactly  locating  such  a  fault ;  nor  of  determining  its  exact 
shape,  or  vertical  extent. 

That  the  faulting  was  accompanied  by  much  crumpling  is  plainly  enough 
visible  to  one  standing  on  the  bridge  and  looking  down  upon  the  river  bed 
(at  low  water)  marked  with  beautiful  zigzags  of  the  slate  edges ;  proving 
that  the  crumpling  was  not  merely  in  vertical,  but  equally  in  horizontal  and 
in  fact  all  directions. 

The  overturn  is  proved  also  by  a  70°  S.  dip  in  the  slates  at  the  bridge  ;  by 
the  almost  universal  S.  dip  exposures  throughout  the  slate  belt;  by  the 
great  width  of  the  slate  belt  (4  miles  from  Harrisburg  bridge  up  to  Marys- 
ville  RR.  bridge  in  the  gap)  which  can  only  be  accounted  for  by  many  col- 
lapsed and  overturned  folds  in  the  slate  belt  itself;  also,  by  the  S.  dips  in 
the  outlying  slate  belt  (\  mile  wide)  at  New  Cumberland  ;  and  by  the  S. 
dips  of  the  limestone  further  south,  where  it  emerges  from  the  S.  edge  of  the 
same  ; — all  concurring  in  one  generalization,  viz. ,  that  the  Great  Valley  rocks, 
of  all  kinds,  along  the  Susquehanna  river,  have  been  thrown  into  a  series  of 
folds  large  and  small,  by  a  northward  thrust  of  the  region,  whicfi,  making 
the  folds,  also  tightly  compressed  them,  and  tilted  them  over  to  the  north— 
of  course  giving  a  S.  dip  to  them  all. 

*  An  elaborate  if  not  exhaustive  study  of  this  admirable  exposure  was 
published  in  report  MM,  1879,  pp.  311  to  362.  The  main  facts  and  my  deduc- 
tions from  them  will  be  given  in  a  subsequent  chapter  xxviii. 


326  GEOLOGICAL   SURVEY    OF   PENNSYLVANIA. 

the  Adams  county  line;  opened  more  or  less  for  a  mile  along 
the  outcrop ;  but  main  output  from  one  large  quarry  of  flux 
for  Pine  Grove  furnace,  say  2500  tons  a  year  ;  thickness  of 
beds,  100';  dip  25°  to  30°  S.  E.;  stone  blue,  massive,  low  in 
silica';  pit  250'x75'x50'  deep.* 

Franklin  county  quarries. 

Williamson'1  s  quarry  (Hawbecker' s)  on  S.  Penn.  Br. 
Cumb.  Val.  RR.  2  m.  W.  from  main  line  above  Marion ; 
near  the  top  of  formation  He  (Trenton),  the  slates  of  III 
outcropping  to  the  W.  and  N.  E.  of  the  quarry  ;  large  and 
fine  faces  ;  75'  to  100'  of  beds  dipping  45°,  S.  E.  away  from 
the  slate  belt,  and  therefore  overturned. 

Mt.  Alto  quarry,  f  m.  from  furnace ;  60'  face  of  beds 
dipping  S.  E. ;  good  but  rather  magnesian  flux  stone;  mixed 
with  Harshman  quarry  flux  at  Quincy,  which  shows  carb. 
lime,  95.482;  carb.  mag.,  2.262;  ox.  iron  and  al.,  0.440; 
silica,  2.340.f 

*  Mr.  King  reports  that  these  beds  contain  only  4  per  cent  carb.  mag.  and 
5  of  silica  ;  while  the  dolomitic  limestone  in  the  neighboring  ore  bank  con- 
tains 40  of  carb.  mag.  and  only  1  of  silica.  He  says  the  "fat"  valley  stone 
shows  12  of  silica;  and  only  0.005  of  sulphur,  as  against  0.125  sulp.  in  Pine 
Grove  stone.  The  car  wheel  iron  of  Pine  Grove  requires  a  minimum  of 
sulphur,  and  the  chemical  composition  of  the  flux  is  therefore  carefully 
studied. 

t  All  the  limestone  quarries  described  in  the  preceding  pages,  from 
Reading  to  Mt.  Alto,  are  more  fully  detailed  in  d'Invilliers'  Report  in  An. 
Rt  1886,  part  iv,  pp.  1517  to  1562,  in  an  order  from  S.  W.  to  N.  E.  But  little 
or  no  account  is  taken  of  scores  of  farm  quarries  of  very  small  size,  mere 
pits  for  obtaining  a  few  loads  of  stone  to  build  houses,  or  other  farm  use. 


MAGNESIAN   BEDS   IN   NO.    II.  327 


CHAPTER  XXVIII. 
Magnesian  beds  in  No.  II. 

The  most  striking  phenomenon  of  this  great  formation  is 
the  subdivision  of  its  vertical  column  into  hundreds  of  beds 
of  limestone  and  of  dolomite  or  magnesian  limestone, 
arranged  alternately,  regardless  of  their  thicknesses,  which 
vary  from  less  than  an  inch  to  several  feet  or  even  yards. 

This  phenomenon  seems  universal  to  the  formation, 
making  its  appearance  in  every  natural  rock  exposure  and 
in  all  quarries  ;  compelling  a  systematic  selection  of  certain 
beds  only  for  the  service  of  iron  smelters  and  lime  burners, 
and  the  rejection  of  the  others  in  mining. 

It  was  long  ago  well  known  that  some  of  the  beds  of  the 
formation  were  highly  magnesian,  and  that  other  beds  were 
comparatively  pure  limestones  ;  but  no  clear  idea  had  been 
obtained  of  (1)  the  relative  number  of  the  two  kinds  in  any 
given  thousand  feet  of  the  series ;  nor  (2)  of  the  relative 
proportion  of  the  total  thickness  of  one  kind  to  that  of  the 
other  ;  nor  (3)  of  the  range  of  variation  of  magnesia  in  any 
one  bed,  from  top  to  bottom,  or  along  the  strike,  or  down 
the  dip  ;  nor  (4)  whether  such  variations  in  the  charge  of 
magnesia  bore  any  fixed  relation  to  the  variable  sum  of 
other  impurities  in  the  limestone. 

The  geological  and  chemical  literature  of  dolomites  and 
magnesian  limestone  rocks  was  very  extensive ;  but  these 
special  features  of  their  sedimentation  had  not  been  suffi- 
ciently studied  either  in  Europe  or  in  America.  The  atten- 
tion of  geologists  was  fixed  chiefly  on  a  search  for  some 
probable  theory  of  the  origin  of  dolomite  beds  as  such  ;  and 
the  discussion  of  that  special  subject  by  European  geolo- 
gists was  intensified  by  the  Austrian  survey  of  the  Tyrolean 
Dolomite  Alps,  about  twenty  years  ago.* 

*  Richthofen  in  1874  discussed  the  Coral  reef  origin  of  the  Schlern   Dolo- 


328  GEOLOGICAL   SURVEY    OF   PENNSYLVANIA. 

The  iron  masters  of  Pennsylvania  have  always  been  par- 
mites  in  the  Tyrol.  (Zeitschrift  Deutscb.  Geol.  Gesell.  Berlin,  XXVI,  ii. 
225-256.) 

Mojsisovics  defended  Richthofen's  separated  coral-reef  theory ;  referred 
the  conglomerated  portions  and  oblique  lamination  to  surf  action,  and  the 
thin  beds  to  lagoon  distribution.  (Sitz.  K.  Ak.  W.  Wien,  Math.  N.  H.  Classe, 
Abt.  1,  Vol.  71,  p.  719.) 

Hoernes  in  1875  published  a  preliminary  notice  of  his  views  on  the  genesis 
of  the  Tyrolean  dolomite  beds,  in  the  Verhand.  K.  K.  G.  R.  p.  290,  and  at  p. 
266,  notices  their  change  eastward. — In  1876  he  published  another  paper  on 
the  formation  of  dolomite  beds  in  the  same,  pp.  76  to  80. — Afterwards  a  full 
description  of  this  chemical  theory  of  Hoernes  and  Dcelter  appeared  in  the 
Jahrbuch  K.  K.  G.  R.  XXV,  iii,  293  to  332,  giving  the  literature  of  the  sub- 
ject up  to  date ;  a  description  of  the  Tyrolese  beds  and  other  Alpine  expos- 
ures ;  analyses ;  and  their  conclusion  that  the  poor  beds  were  of  organic 
origin,  and  that  the  rich  beds  were  possibly  organic  limestones  enriched 
soon  after  deposit  by  the  reaction  of  magnesium  chloride ;  the  proportion  of 
lime  being  afterwards  lowered  by  the  sol  vent  action  of  carbonated  waters. 

Hoppe-Seyler,  in  1875,  showed  experimentally  that  dolomite  cannot  be 
artificially  produced  at  ordinary  temperatures  ;  maintaining  that  the  mag- 
nesia of  dolomite  beds  could  not  have  come  from  eruptive  rocks,  but  must 
have  come  from  sea  water  heated  by  submarine  volcanos  sufficiently  to  ad- 
mit of  magnesian  precipitations.  (Zeitschrift  D.  G.  S.  Berlin,  p.  495-930.) 

Green  (W.  L.)  in  1875  suggested  the  formation  of  extensive  magnesian 
limestone  oceanic  deposits  out  of  the  fine  detritus  of  olivine  volcanic  sand 
and  dust,  mixed  with  the  extensively  distributed  fine  detritus  from  coral- 
reels.  Such  a  mixture  must  cover  an  immense  area  of  sea  bottom  around 
the  Hawaian  islands  and  in  other  parts  of  the  Pacific.  (Jour.  R.  Geol.  S. 
Ireland  [2]  IV,  iii,  140- 1*3.) 

Murray  (John)  describes  the  universal  distribution  of  volcanic  debris 
over  the  ocean  floor,  in  the  shape  of  deep  sea  mud,  containing  also  peroxide 
of  manganese,  native  iron  and  cosmic  dust,  with  local  mixtures  of  wind 
dust  from  desert  regions  ;  and  supposes  the  mixture  of  such  deposits  with 
limestone  precipitations  to  account  for  the  red  earth  of  Bermuda,  Bahamas, 
Jamaica,  etc.,  but  thinks  that  no  analogous  sediments  can  be  found  in  the 
strata  of  past  geological  ages.  (Proc.  R.  S.  Edinburgh,  IX,  pp.  247-261.) 

E.  T.  Hardman  discussed  in  1877  his  views  of  the  history  of  Carboniferous 
Irish  dolomites,  favoring  their  chemical  precipitation.  (Proc.  R.  Irish  Acad. 
[2]  II,  7,  pp.  705-730.) 

Analyses  of  rock  dolomite  beds  in  the  Carboniferous  Limestone  and  Cal- 
caire  Grossier  beds  of  Flanders,  and  in  the  magnesian  limestone  beds  of 
Durham  (4  in  number)  by  Corenwinder,  will  be  found  in  the  Ann.  Soc. 
Geol.  du  Nord  (Lille)  1870-4,  p.  17,  18,  19.— Analyses  of  Silurian  dolomitic 
sandstones,  by  Stolba,  are  noticed  in  Jour.  Chem.  S.  London,  [2]  XII,  967, 
1874. — Analysis  by  Roth,  using  dilute  acetic  acid  on  dolomite  limestone,  may 
be  found  in  Min.  Mittheil.  heft  i,  p.  69,  1876.— Analyses  of  dolomitic  con- 
glomerate, with  description  of  beds  (Trias)  are  given  by  W.  W.  Stoddart, 
in  Proc.  Bristol  Nat.  S.  II,  i,  39-47,  1876. — Analyses  of  insoluble  residues  of 
dolomitic  limestones  (Cretaceous,  Jurassic,  Triassic,  Carboniferous  and 
Devonian),  are  given  by  Pfaff,  in  the  Zeitschrift  Ges.  Nat.  [3]  III,  p.  273- 
294,  1878. 


MAGNESIAN   BEDS   IN   NO.    II.  329 

ticular  in  the  choice  of  the  beds  they  quarried  for  flux 
stone,  being  guided  for  a  long  time  by  experience  alone, 
but  in  later  years  by  the  analyses  of  their  own  chemists.  A 
vast  number  of  such  analyses  are  on  record  in  the  office 
books  of  iron  works  ;  but  while  they  show  the  range  of 
dolomite  variability  in  the  formation  as  a  whole,  they  do 
not  show  the  variability  of  its  beds  in  series  of  regular 
superposition  ;  at  least,  not  in  a  series  of  beds  sufficiently 
large  to  furnish  a  broad  generalization.  Serial  researches 
into  the  chemical  character  of  the  quarry  beds  on  the  Le- 
high  were  not  carried  far  enough,  as  may  be  seen  by  refer- 
ence to  Prof.  Prime's  Report  D3,  1883,  p.  187,  where  an- 
alyses are  published  of  18  sub-divisions  of  5  beds  in  Trox- 
all's  quarry,  and  of  14beds  inEberhard's  quarry,  the  latter 
series  being  lower  in  the  formation  than  the  former,  and 
nothing  coming  of  the  investigation  except  the  two  facts  : 

(1)  that  there  is  very  little  variation  within  each  series  ;  and 

(2)  that  the  upper  series  is  almost  exclusively  limestone, 
and  the  lower  almost  wholly  magnesian.* 

In  like  manner  a  series  of  analyses  by  Dr.  Genth  of  12 
samples  of  the  magnesian  limestones  (No.  II)  taken  from 
the  banks  of  the  Schuylkill  between  Conshohocken  and 
Potts  Lauding,  and  from  beds  low  in  the  formation,  but  not 
consecutive,  merely  showed  great  variations  in  percentage 
of  magnesia,  and  especially  of  silica ;  three  of  them,  in 
fact  justify  ing  the  term  k'  Calciferous  sandstone";  and  three 
others  being  extraordinarily  pure  limestones,  f 

*Thus  :  Sub-divisions  of  Troxall's  quarry  bed  A,  carb.  lime,  77,  80,  82,  82, 
80;  B.  76,  86,  84,  72,  77,  74;  C.  66,  54;  D.  76,  61,  84,  50;  E.  87.— Carb.  Mag.  A. 

1,  1,  2,  7,  4  ;    B.    1,  0.4,  4,  3,  2,  3  ;    C.    15,  14 ;  D.  4,  2,  2,  1 ;  E.   0.5.     (There  are 
probably  errors  of  transcription  in  the  second  and  fourth  layers  of  bed  D.) 
—The  Eberhard  beds  read  :  Carb.  lime,  55,  54,  68,  61,  64 ;  60,  55,  61,  60,  57  ;  60, 
59,  50,  57.      Carb.  mag.  35,  36,  21,  27,  23  ;   21,  27,  23,  33,  26 ;  31,  25,  22,  9.     Silica, 

2,  3,  3,  4,  4 ;  4,  12,  6,  7  ;  3,  6,  4,  16;    Ferric  Ox.  and  alumina,  7,  7,  7,  8,  9 ;  14,  6, 
7,  2,  9 ;  6,  9,  14,  17.     Phosphorus,  .007,  .019,  .026,  .017,  .015 ;  .007,  .013,  .005,  .011, 
.003  ;  .002,  .012,  trace,  .017.     A  residue  of  carbonaceous  matter  varying  from 
0.12  to  0.84  was  left  when  any  of  the  limestones  were  dissolved  in  acids,  and 
represented  the  organic  life  of  that  age.     All  the  Harrisburg  analyses  showed 
such  carbon  in  percentages  from  0.166  up  to  0.560.     Life  must  have  been  very 
abundant. 

t  See  report  C6,  1881,  page  126.— Carb.  lime,  60,  55,  42,  40,  48;  63,  92,  53,  58, 
61 ;  93,  85.— Insoluble  residue,  ?,  3,  26,  46,  38 ;  3,  8,  10,  6,  7  ;  6,  5.— A  complete 


330  GEOLOGICAL   SURVEY   OF   PENNSTLVANIA. 

A  large  number  of  analyses  of  limestone  specimens  from 
various  other  areas  of  No.  II  in  the  State,  made  by  the 
Chemist  of  the  Survey,  Mr.  McCreath,  and  published  in  his 
reports  M,  M2,  M3,  and  in  the  reports  of  the  various 
counties  where  they  were  collected,  do  nothing  more  than 
repeat  and  enlarge  the  testimony  to  the  infinitely  various 
proportions  of  lime,  magnesia,  silica,  alumina,  etc.  in  the 
beds  of  the  formation,  leaving  the  true  mode  of  the  varia- 
tion from  limestone  to  dolomite,  to  say  nothing  of  its  origin 
and  cause,  quite  unexplained.  Up  to  1877,  no  idea  of  how 
the  magnesian  and  non-magnesian  layers  are  arranged  had 
been  got ;  no  law  of  regular  or  irregular  interstratification 
had  made  itself  apparent ;  it  was  not  possible  to  say 
whether  the  several  magnesian  beds  resembled  each  other, 
whether  the  several  purer  limestone  beds  were  alike  or  not, 
nor  in  what  degree,  if  at  all,  the  two  series  represented  two 
kinds  of  physical  action  intermittent  in  the  ancient  seas. 
Yet  until  this  was  learned  we  could  not  make  the  first  step 
towards  a  stable  rational  theory  of  our  larger  limestone  for- 
mations. 

I  therefore  directed  to  be  made  in  1877  a  careful  sampling 
of  115  beds  (with  a  total  thickness  of  370  feet)  exposed  at 
the  old  Walton  (McCormick)  quarry  opposite  Harrisburg  by 
the  Northern  Central  railway  cutting  for  a  length  of  800 
feet :  a  consecutive  series  of  beds,  all  conformable,  and 
dipping  regularly  southward  at  an  angle  of  30°* 

This  afforded  a  good  opportunity  for  collecting  two  sets 
of  samples,  two  samples  from  each  bed,  one  at  the  soil  above, 
the  other  at  the  level  of  the  railroad,  therefore  from  15  to 
80  feet  apart  according  to  the  varying  depth  of  the  cut;  and 

analysis  of  the  fifth  bed  gave  :  carb.  lime,  40.27  ;  carb.  mag.  31.24;  insoluble 
residue  28.49  (of  which  24.23  was  silicic  acid  or  quartz).  The  specimens 
analysed,  No.  7106,  etc.  are  labeled  and  preserved  in  the  Museum  of  the 
survey. 

*The  cut  was  surveyed  and  the  beds  marked  by  Mr.  Sanders,  who 
numbered  them  from  1  to  98  (see  Table  X,  M2,  p.  353).  Mr.  Hartshorne  saw 
reasons  for  subdividing  some  of  the  beds  and  renumbered  them  from  1  to 
115  (see  Table  XI,  on  p.  354).  Mr.  Sanders'  sum  total  footed  up  372'  9". 
Mr.  Hartshorne's  remeasurement  footed  up  370'  10". 


MAGNESIAN   BEDS   IN   NO.    II. 


331 


reduced  from  paqe-plcties  in  Rcpf-.  MM,1S73,  pp.355-35tf. 

§ 


332  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

sometimes  a  third  or  intermediate  sample.  Many  of  the 
analyses  of  individual  samples  were  duplicated.* 

A  cross  section  of  the  exposure  was  published  in  M2,  p. 
344,  and  repeated  (cut  up  into  eight  lengths)  in  four  page 
plates,  pp.  355  to  235  ;  all  the  beds  numbered  from  1  to  115 
along  the  bottom  line  ;  thickness  in  feet  and  inches  of  each 
bed  given  on  its  face  edge  ;  percentage  of  carb.  magnesia 
given  below  and  above;  the  lime  beds  left  white;  the  magne- 
sian  beds  shaded,  the  darker  or  lighter  shading  showing  the 
proportionately  more  or  less  magnesian  character  of  the  bed. 

This  cross  section  reduced  one  half  linear  as  exhibited  on 
plate  7,  page  331,  will  give  the  reader  a  general  idea  of  the 
scope  of  the  investigation  and  the  facts  it  brought  to  light. 
For  a  better  study  of  it  the  chemist  or  geologist  is  expected 
to  resort  to  my  original  memoir  in  Mr.  McCreath's  Report 
M2,  the  results  of  which  I  shall  here  state  as  succinctly  as 
may  be.f 

Table  I  (M2,  pp.  345,  346,  347)  shows  in  vertical  columns 
the  carb.  lime,  carb.  mag.  and  insol.  matter  percentages  of 
each  bed,  at  grade  and  at  top  of  cut4 

*  The  investigation  was  put  under  the  direction  of  the  Chemist  of  the 
Survey,  Mr.  A.  S.  McCreath.  The  analyses  were  made  in  the  Laboratory 
of  the  Survey  at  Harrisburg  by  Mr.  Joseph  Hartshorne  in  1877-8;  and  con- 
cluded by  Mr.  S.  S.  Hartranft'in  the  summer  of  1878.  The  analyses  were 
published  in  full  in  Mr.  McCreath's  Report  M2,  1879,  pp.  312  to  341 ;— with 
three  very  interesting  analyses  of  calcite  contained  in  beds  9  and  23  (showing 
about  88  p.  c.  of  carb.  lime;  10  of  insoluble  matter;  1  to  2  of  carb.  mag.; 
about  0.2  of  carb.  iron  ;  about  .03  of  sulphur,  and  about  .3  of  phosphorus. ) ; 
— also  two  analyses  of  the  flint  in  bed  5  (showing  90  p.  c.  silica  ;  6  to  9,  carb. 
lime;  0.5  carb.  mag.;  0.6  carb.  iron  ;  .02  to. 06  alumina;  0.05  sulphur;  and 
traces  of  phosphorus.  See  M2,  p.  342). 

|  A  preliminary  account  of  them  will  be  found  in  a  paper  read  before  the 
Amer.  Philos.  Soc.,  Phila.,  Dec.  20,  1877,  and  published  in  the  society's  pro- 
ceedings of  that  date. 

f  Abnormal  analyses  are  brought  out  by  bracketing  unexpected  and  per- 
haps erroneous  percentages,  thus: — 


Bed  17,    .   . 

26,  .  . 
43,  .  . 
62,  .  . 

68,  .  . 
77,  .  . 
80,  .  . 
81, 

IAn 
Grade. 
.    .      96.60 
.    .      90.00 
.    .      97.80 
.    .    [49.80 
.    .      85.10 
.    .      85.50 
.    .      79.80 
54.90 

ie  Carb. 
Top. 
[60.20] 
[70.!<5] 
[91.00] 
61.90 
96.00 
97.90  ' 
95.90 
56.70  , 

Magn 
Grade. 
1.10 
6.80 
1.30 
31.90 
"10.40 
'  9.80: 
=  9.90: 
35.70 

es.  Carb. 
Top, 
[33.40] 
6.30 
[  1.30] 
28.40 
2.30 
1.80 
2.00 
24.00 

Insol.  Matter. 
Grade.             Top. 
1.10         [  5.90 
3.40         [22.95 
1.30        [  7.90 
[16.90]          8.20 
3.20            1.90 
4.50             1.00 
9.40            2.60 
7.70          18.40 

84,  . 

66.80 

[75.601 

"27.20' 

16.30 

4.40            5.60 

N.  B.     All  percentages  given  in  these  tables  are  only  to  one  or  at  most  two 
figures  of  decimal. 


MAGNESIAN    BEDS    IN   NO.    II.  333 

The  first  thing  noticeable  is  that  not  a  single  one  of  the 
115  beds  is  entirely  destitute  of  the  magnesia  carbonate ; 
and  that  in  no  bed  does  the  magnesia  carbonate  rise  high 
enough  to  make  the  rock  a  perfect  dolomite.* 

The  second  remarkable  fact  is  that  the  alternation  of 
magnesian  and  non-magnesian  (i.  e.  of  high  and  low  mag- 
nesian  limestone)  beds  is  constant,  rapid  and  sharp  ;  for  in 
only  one  case,  that  of  the  group  of  beds  6,  7,  8,  9,  10,  11,  is 
there  any  appearance  of  a  gradual  increase  and  decrease  of 
magnesia  in  a  sedimentary  sense,  f  Seldom  a  bed  occurs 
with  any  intermediate  percentage  between  the  very  high 
and  very  Iow4 

The  third  fact  is  equally  striking  and  important,  viz.,  that 
so  far  as  analyses  at  the  two  ends  of  the  exposure  of  a  bed 
can  warrant  the  assertion,  each  bed  is  wonderfully  homo- 
geneous in  its  magnesian  character,  whether  .high  or  low. 
In  only  a  few  cases  is  there  any  practical  difference  in  the 
percentage  of  magnesia  at  grade  and  at  top.  In  those  that 
do  occur,  however,  the  difference  is  as  great  as  that  which 
marks  the  alternate  beds.§ 

A  fourth  important  fact  is,  that  the  greater  percentages 
of  insoluble  matter  (silicates)  are  almost  invariable  found 
in  the  high  magnesian  beds,  the  beds  which  are  free  of 
magnesia  being  free  of  silica  and  alumina  likewise. 

*Bed  85  has  only  0.9  at  grade  (4.1  at  top);  and  bed  2  has  3&50  at  grade 
(39.75  at  top). 

f  In  these  the  mag.  carb.  p.  c.  runs  thus:  1.40,  3.60,  14.50,  24.80,  8.05,  1.80 at 
grade  (and  1.30,  3.70,  7.50,  27.00,  8.15,  1.30  at  top).  This  is  also  a  fair  example 
of  the  remarkable  uniformity  of  the  two  percentages  at  grade  and  at  top  in 
each  bed;  proving  (1)  the  general  chemical  accuracy  of  the  laboratory 
work,  and  (2)  the  general  homogeniety  of  each  bed  from  end  to  end  of  its 
exposure. 

t  Such  however  are  beds  14,  33,  36,  38,  55,  64,  84,  97,  104.— Of  the  32  beds 
from  84  to  115,  half  of  them  are  low  (12  under  2.00,  3  under  3.00,  the  remain- 
ing one  4.6);  and  of  the  other  half  all  but  two  are  high  (9  range  between 
36.00  and  30.00,  five  between  30.00  and  25.00  ;  one  is  17.00,  the  other  14.00). 
On  page  348,  M2,  these  are  so  arranged  in  a  table  that  the  rapid  alternate  up 
and  down  oscillations  are  patent  to  the  eye.  It  is  specially  remarkable  how 
few  beds  occupy  an  intermediate  chemical  position  between  the  extremes. 

§  In  how  many  of  these  instances  the  difference  may  be  due  to  some 
accident  in  misplacing  the  samples,  I  cannot  tell ;  but  they  are  so  few  that 
they  offer  no  great  obstacle  to  a  conviction  that  each  bed  is  really  a  homo- 
geneous deposit 


334  GEOLOGICAL   SURVEY    OF   PENNSYLVANIA. 

Other  facts  are,  that  the  planes  of  separation  between 
bed  and  bed  are  ordinary  bed  planes  as  in  sandstone  and 
shale  strata ; — that  no  current,  cross,  or  false-bedding  is 
visible  ; — that  some  of  the  beds  (of  both  species,  magnesian 
and  non-magnesian)  are  only  a  few  inches  thick,  while 
others  are  6',  8',  10',  12',  even  14'  (bed  68)  thick  ;  that  there 
is  no  rule  by  which  to  connect  the  thin  beds  with  one  species, 
nor  the  thick  beds  with  the  other ; — that  a  limestone  layer 
only  5  or  6  inches  thick  crosses  the  whole  exposure  between 
two  equally  thin  layers  of  dolomite,  with  no  show  of  grading 
into  each  other  (the  same  analysis  being  got  at  both  ends; — 
that  two  thick  limestone  strata  will  enclose  a  thin  magnesian 
layer  ;  and  vice  versa  two  massive  dolomite  beds  will  enclose 
a  thin  limestone  layer  ; — and  finally,  that  beds  of  the  highest 
and  lowest  magnesian  character  lie  directly  and  repeatedly 
in  contact  with  each  other. 

Negative  deductions  from  the  facts. 

The  only  generalization  I  can  make  from  the  above  data 
is  a  negative  one.  namely :  that  no  theory  of  percolation 
can  account  for  the  facts  ;  that  no  theory  of  more  rapid  dis- 
solution of  carbonate  of  lime,  leaving  a  growing  charge  of 
carbonate  of  magnesia  behind,  will  apply  to  rocks  which 
are  neither  honeycomb,  nor  visibly  porous,  nor  unusually 
cleft, nor  otherwise  disturbed;  and  that  any  theory  to  account 
for  the  presence  of  the  magnesia  must  treat  the  layers  of 
both  species  as  equally  mechanical  sediments  ;  especially, 
seeing  that  the  larger  part  of  the  insoluble  matter  resides 
in  those  which  contain  most  magnesia ;  while  magnesia  is 
present  in  all  of  both  kinds. 

Amount  of  Magnesia  present. 

There  only  remains  to  be  considered  the  question:  whether 
there  be  any  feasable  mode  of  calculating  the  actual  quantity 
of  carbonate  of  magnesia  in  the  formation,  or  in  this 
exposed  subdivision  of  it,  in  proportion  to  the  actual 
quantity  of  carbonate  of  lime  and  insoluble  matter  which 
together  make  up  the  bulk  of  the  deposits.  In  other  words  : 
what  are  the  average  proportions  of  the  three  principle 


MAGNESIAN   BEDS   IN   NO.    II.  335 

elements  of  strata  370  feet  thick,  by  which  we  can  judge  of 
their  distribution  through  the  whole  formation  several 
thousand  feet  thick. 

In  attempting  this  problem  the  beds  were  at  first  grouped 
in  fives  and  averages  taken  (Table  II,  p.  349,  M2);  then  in 
tens  (Table  III,  p.  350);  lastly  in  three  groups  of  50,  50  and 
15  (Table  IV),  which  yields  a  final  average  for  the  whole  115 
beds  as  follows  :— C.  L.  80.662  ;  C.  M.  14.215  ;  I.  M.  4.715.* 

Excluding  the  third  element  (insoluble  matter)  and  calling 
the  carbonates  of  lime  and  magnesia  100,  their  average  pro- 
portion to  each  other  in  the  whole  115  beds,  taken  together 
as  a  solid  series,  stands  85.02  :  14.98. 

The  next  step  in  the  calculation  was  to  separate  the  beds 
into  two  series  :  the  limestones  (L.)  and  the  magnesian  lime- 
stones (M.),  and  treat  each  series  separately  to  get  a  grand 
average  for  the  whole.  For  this  purpose  I  selected  the  29 
beds  at  the  north  end  of  the  section  (next  the  limekiln),  15 
of  them  high  in  magnesia  and  14  low,  alternating  with  re- 
markable regularity,  f 

Combining  the  top  and  bottom  analyses  of  these  29  beds, 
we  get  the  following  general  average  analysis  of  the  high 
magnesian  beds  (M)  and  the  low  magnesian  beds  (L):— . 

Table  VII  J  M'     '  C'  L-  63'41  5    C-  M-  28'22  J    Insol.  7.24 

'  t  (L),  .  C.  L.  95.77  ;  C.  M.  2.06  ;  Insol.  1.42  J 
which  is  probably  as  good  a  formula  for  the  chemical  dis- 
tribution of  the  lime  and  magnesia  constituents  of  our 
Cambro-Silurian  (or  Ordovician)  limestones  as  we  are  likely 
to  get  by  any  such  method. § 

*  The  reasons  for  the  failure  of  worthy  results  from  the  smaller  groupings 
are  given  in  M2,  p.  350. 

f  Of  the  164  percentages  five  were  abnormal.  These  were  included  in 
Tables  V,  VI  b  - ,  excluded  from  Table  VII,  p.  351,  the  general  result  being 
however  but  slightly  affected. 

JThe  direct  proportion  of  C.  L.  to  C.  M.  however  is  in  (M)  69.2 :  30.8,  and 
in  (L)  97.9:  2.1  (Table  VIII). 

§To  try  the  method  in  another  form  I  selected  57  high  and  58  low  mag- 
nesian beds  (using  only  the  figures  of  the  fourth  column  of  Table  I)  to  be 
treated  in  two  separate  series,  sub-divided  into  four  groups  of  beds  (1)  beds 
1  to  30 ;  (2)  31  to  60 ;  (3)  61  to  90 ;  (4)  91  to  115.  The  result  was  as  follows  :— 

Table  TX  $  <M) C.  M.  (1)  27.96  (2)23.56  (3)26.05  (4)27.04 

'  \  (L)  C.  M.  (1)  3.01  (2)  2.62  (3)  2.25  (4)  2.00 

giving  a  general  average  of  carbonate  of  magnesia  in  the  57  high  magnesian 


336  GEOLOGICAL   SURVEY    OF   PENNSYLVANIA. 

The  different  thicknesses  of  the  beds  must  now  be  taken 
into  consideration ;  for  no  possible  combination  of  two 
analyses  from  each  bed  of  a  series  could  possibly  give  the 
true  proportion  of  Jime  and  magnesia  in  the  whole  series 
unless  the  beds  of  the  series  were  all  of  equal  thickness  * 

Treating  the  beds  according  to  their  thicknesses  by  the 
formula  given  in  the  foot  note, but  using  only  the  percentages 
of  C.  L.  arid  C.  M.  in  columns  1  and  3  of  Table  I  (that  is 
the  samples  at  grade  line)  I  got  the  results  of  Table  XII, 
(M2,  p.  359):— 

132.6'  (beds      1  to   50) C.  L.  92.00  C.  M.  12.20 

179.9'  (    "       51  to  100) "     79.25  "      14.00 

59.5'  (  "  101  to  115) "   83.75  "   11.86 

371.0'  (  "    1  to  115) "  84.47  "   13.02 

Considering  the  probable  animal  origin  of  the  flints  from 
sponges,  and  the  proven  animal  origin  of  the  oolite  beds 
from  broken  up  bryozoa,  together  with  the  known  abund- 
ance of  molluscs,  articulates,  etc.  in  the  waters  of  that  age, 
it  is  reasonable  to  ascribe  part  of  the  surplus  of  lime  over 
magnesia  to  that  cause ;  the  small  amounts  of  sulphur  to 
plant  life  ;  and  the  small  amounts  of  phosphorus  to  animals 
like  Lingula  which  preferred  phosphate  of  lime  to  carbon- 
atev  of  lime  for  making  their  shells ;  or  perhaps  to  large 
armored  fish  which  a  recent  discovery  informs  us  lived  in 
great  numbers  at  the  beginning  (or  before  the  beginning)  of 
the  Trenton  age ;  though  why  no  traces  of  such  fish  have 
been  reported  from  any  Lower  Silurian  outcrop  in  the 
world  except  only  at  one  spot  on  the  Colorado  river  is 
wonderful  enough. 

beds,  25.89 ;  and  in  the  58  low  magnesian  beds,  2.53.  It  will  be  noticed  that 
this  result  differs  somewhat  from  that  in  Table  VII  in  the  text  above,  where 
the  figures  read  28.22  and  2.06 ;  but  not  more  than  we  might  expect  from 
using  115  beds  in  one  case  and  only  29  beds  in  the  other. 

*  Suppose  for  the  sake  of  illustration  we  have  a  series  of  100  beds,  half  of 
them  averaging  C.  M.  2.00,  the  other  half  averaging  C.  M.  30.00 ;  if  they  were 
all  of  equal  thickness  the  general  average  would  be,  of  course,  C.  M.  16.00. — 
But  suppose  the  first  fifty  had  an  average  thickness  of  only  1',  and  the 
other  fifty  an  average  of  6g'  (making  a  total  of  375'),  the  calculation  must 
run  thus:  50Xl'X2.00  -f  50  X  6. 5' X  30. 00=9850  percent.;  which  divided  by  375' 
gives  &  general  average  of  C.  M.  26.70. — If  the  1'  beds  were  30.00  p.  c.  and 
the  65'  beds  were  2.00  p.  c.  the  general  average  would  be  only  C.  M.  5.73. — 
Of  course  all  this  is  only  true  on  the  presumption  that  each  bed  is  in  itself 
homogeneous  and  would  give  the  same  percentage  wherever  sampled  ;  which 
is  evidently  not  quite  the  case. 


HYDRAULIC    CEMENT   QUARRIES    OF   NO.  II.  337 


CHAPTER  XXIX. 

Hydraulic  Cement  Quarries  of  No.  lie  (Trenton]  on  the 
LehigJi — Gypsum. 

These  were  referred  to  shortly  in  Chapter  XXV,  but 
their  importance  demands  a  more  detailed  description. 
Four  companies  have  quarried  and  burned  the  stone,  two 
on  the  west  and  two  on  the  east  bank  of  the  Lehigh  at 
Coplay,  where  the  Trenton  limestone  with  its  cement  beds, 
crosses  the  river.  These  works  are  described  in  Prof. 
Prime's  Report,  D2,  1878,  pages  59  to  67. 

The  LeJiigh  Hydraulic  Cement  Company  commenced 
operations  in  1872,  on  the  west  bank,  1  m.  above  Coplay 
station,  Lehigh  Valley  RR.  In  1874  the  mill  was  burned 
down.  It  had  3  run  of  stone,  and  could  grind  300  bbls.  a 
day  ;  four  kilns  of  No.  12  pattern  as  decribed  in  Gen.  Gil- 
more' s  book  on  cement ;  quarry  near  mill ;  color  of  cement 
light  yellow  ;  very  like  in  color  and  quality  the  old  Lehigh 
and  the  Allen  cements. 

The  Coplay  Cement  Company,  organized  in  1867,  have  11 
kilns  a  short  distance  above  Coplay  station,  6  miles  above 
Allentown  ;  the  quarry  adjacent ;  a  steam  engine  hoisting 
the  quarry  stone  to  the  kilns  for  burning  Anchor  cement, 
and  at  the  same  time  running  the  crushers  for  Portland 
cement;  7  set-kilns  burn  Saylor's  Portland  cement  (Hu- 
bett's  London  pattern)  built  of  cement,  concrete,  firebrick 
and  iron ;  total  capacity  2,500  bbls.  of  Portland  cement 
clinker  per  month.  The  other  4  are  draw-kilns,  of  Rosen- 
dale,  N.  Y.  pattern  (Gilmore's  No.  12),  burning  Anchor 
cement,  300  bbls.  per  day.  Store  room  capacity  15,000  bbls. 

Some  beds  of  the  quarry  are  fit  for  Portland,  others  for 
Anchor  cement ;  but  good  technical  knowledge  is  needful 
to  decide  what  stone  to  use  and  what  to  reject,  that  the  pro- 
duct may  successfully  stand  the  engineer's  tests.  Of  the 
22" 


338 


GEOLOGICAL   SURVEY    OF  PENNSYLVANIA. 


samples  of  Portland  cement  made  from  8  beds  (of  which 
analyses  are  given  below)  some  were  very  good,  while  others 
fell  far  below  the  required  strength.* 

The  requirements  of  the  Department  of  Docks,  New 
York,  in  purchasing  are  as  follows :  Weight,  per  barrel, 
400  Ibs. ;  weight,  per  bushel,  110  IDS.;  fineness,  80  per  cent.; 
tensile  strength,  at  seven  days,  250  Ibs.  per  square  inch.f 

Tests  of  Saylor's  Portland  cement  as  packed  and  offered 
for  sale  in  market,  4  in  number,  are  tabled  D2,  p.  61  : — 
Weight  per  cubic  foot,  112  Ibs.  ;  fineness  through  a  2500 
mesh  sieve,  85  to  100  p.  c.  ;  date  of  grinding  Jan.  12  ;  dates 
when  blocks  were  made,  April  26  to  30  ;  weight  of  block,  24 
and  25  oz.  ;  weigh  t^  of  water  in  each  block,  5J  to  6  oz.  ; 
temperature  of  cement  and  water.  60°  Fahr. ;  time  to  set  in 
mould,  16  to  20  minutes  ;  time  left  in  mould,  90  minutes  ; 
immersed  immediately  ;  left  in  water  6  to  7  days  ;  broken 
immediately  on  being  taken  out  of  water  ;  age  when  broken 
.  6  to  10  days  ;  average  tensile  strain  on  square  inch,  411,  392, 
426,  566  Ibs. ;  3  blocks  made  of  each  ;  tensile  strain  per 


* Analyses  of  quarry  rock  for  Portland  cement  by  Mr.  John  Eckert,  under 
Prof.  W.  B.  Chandler. 


Silica 

12  88 

12  81 

13  72 

14  68 

15  03 

15  40 

1     79 

14  32 

Alumina  
Ferric  oxide,  
Carbonate  of  lime  
Sulphate  of  lime,  
Carbonate  of  magnesia  
Phosphoric  acid  
Organic  matter,  ....  ... 

4.25 
1.09 
72.87 
1.60 
4.69 
.10 
1.57 

4.86 
.97 
72.64 
1.68 
4.62 
.11 
1.72 

4.09 
1.04 
71.54 
1.79 
4.37 
.10 
1.78 

5.32 
1.12 

69.26 
2.29 
3.  67 
.09 
1.68 

3.97 
1.93 
74.12 

2.41 
.13 
1.47 

4.26 

74!  66 
.86 
2.66 
.09 

.50 
.34 
7  .95 
.75 
.84 
.06 
1.46 

4.20 
1.65 
73.12 
2.02 
4.09 
.17 
1.31 

Total  

99.05 

99.41 

98.43 

98.11 

100.25 

101.19 

100.69 

100.88 

Analyses  of  Portland  cement  made  from  the  above  beds. 


Silica 

Alumina 

Sesquioxtde  of  iron, 

Sulphate  of  lime 

Lime 

Magnesia 

Total,   . 


10.11 
1.61 

1.78 


23.40 
8.06 
2.38 
2.44 

59. 94 
3.21 

"ggls" 


23.21 
8.35 
2.74 
2.36 


23.07 
7.32 
2.49 
2.17 


97.36 


f  A  copy  of  official  report  on  1,000  bbls  of  Saylor's  Portland  cement,  tested 
Nov.  13  to  Dec.  20,  1877,  is  printed  in  D2,  p.  62.  Average  gross  weight  per 
barrel,  400  Ibs.;  average  weight  of  U.  S.  bushel,  131  Ibs.;  number  of  barrels 
sampled,  105;  average  fineness,  82  p.  c.;  average  tensile  strain  per  sq.  in., 
347  Ibs.;  number  of  minutes  in  mould,  53  minutes. 


HYDRAULIC    CEMENT   QUARRIES    OF   NO.  II.  339 

section  of  each  block,  (1)  875,  976,  925  ;  (2)  825,  825,  1000 ; 
(3)  950,  1025,  925  ;  (4)  1325,  1350,  1150  Ibs.* 

Saylor's  Cement  is  fully  equal  to  the  English  and  French 
Portland  cement  and  is  manufactured  by  the  same  patent 
Aspdin  process  (L825),  except  that  the  quarry  rocks  at  Cop- 
lay  yield  all  the  needful  elements,  and  therefore,  does  not 
require  the  addition  of  clay,  etc.f 

Anchor  Cement  is  a  patented  light  burnt  cement  of  a 
peculiar  chemical  composition  :  sets  rapidly  ;  has  great  co- 
hesion ;  becomes  uncommonly  hard  both  under  water  and 
in  air  ;  has  a  beautiful  greenish  gray  color  ;  makes  smooth 
and  uniform  drain  pipes,  turned  out  rapidly  from  the  mould; 
is  desirable  for  beton  or  concrete  for  bridge  piers  and  abut- 
ments.:{: 

The  Old  LehigJi  Cement  Works  near  Siegfried's  bridge, 
E.  bank  of  Lehigh  river,  erected  by  the  Lehigh  Naviga- 

*Prof.  Prime  writes  (D2,  p.  62)  Portland  cement  in  England  is  made  by 
burning  mixture  of  chalk  and  Thames  river  clay  to  a  partial  vilification. 
A.11  attempts  to  find  (or  to  properly  mix)  the  proper  rocks  failed  to  produce 
a  cement  equal  to  the  best  English  and  French  brands,  which  is  a  triple 
silicate  of  alumina  and  lime  and  iron,  without  any  free  lime,  'as  a  sharp 
crystalline  powder,  varying  from  dark  to  light  gray,  with  a  bluish  or 
greenish  tint.  The  Coplay  Cement  Company  after  long  and  costly  experi- 
ments in  selecting  and  mixing  several  beds  in  their  quarry  got  an  analj'sis 
thus  : — (1)  Soluble  in  hydrochloric  acid  :  Garb,  lime,  70.34;  carb.  mag.,  4.47; 
carb.  iron,  2.98  ;  (2)  Insoluble  silica  J4.73  ;  alumina,  4.54  ;  ferric  oxide,  0.93; 
magnesia,  0.89;  water,  0.98=total  99.86.  This  mixture,  when  its  carbonic 
acid  was  driven  off  in  the  kiln,  analyzed  :  Silica,  22.77  ;  alumina,  7.03  ;  lime, 
60.91 ;  magnesia,  4.67  ;  ferric  oxide,  4.63=100.  Prof.  W.  T.  Roepper  of  Beth- 
lehem. But  as  the  same  quarry  bed  varies  in  quality,  samples  of  stone  are 
frequently  analyzed  and  burned  in  a  testing  kiln.  The  stone  is  crushed 
and  ground,  thoroughly  mixed  dry  and  tempered  with  water  in  a  pug  mill, 
spread  out  on  drying  floors,  cut  into  bricks,  placed  in  a  kiln  with  alternate 
layers  of  coke  and  burnt ;  the  clinker  is  then  selected,  the  pulverulent 
scarified,  and  the  underburnt  taken  out ;  the  burnt  bricks  then  ground  and 
stored  in  bins  for  a  few  weeks  to  sweat  and  cool  before  shipment  to  Com- 
munipaw  to  be  barreled  and  stored. 

fThe  N.  Y.  Dock  Department  used  5000  bbls.  of  it  in  1877.  The  U.  S 
fortifications  have  made  much  use  of  it ;  Gen.  Gilmore  fully  endorsing  it. 
The  East  River  Bridge  Co.  used  it,  Engineer  Martin  endorsing  it ;  and  it 
received  a  medal  at  the  Centennial  Exhibition. 

fit  was  selected  before  all  other  American  cements  for  the  Giraid  bridge 
at  Philadelphia.  See  reports  of  tests  in  Journal  Frank.  Inst.  Phila.  March 
1874,  p.  181  (copied  verbatim  into  Report  D2,  p.  65, 66).  The  mixture  finally 
fixed  on  was:  Anchor  cement  1  part,  sharp  river  sand  1  part ;  furnaceslag, 
4  parts. 


340  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

tion  Co.  In  1872  leased  by  Gen.  J.  Selfridge  and  enlarged 
to  200  bbls.  a  day  ;  new  quarry  opened  on  Hokendaqua 
creek,  1  m.  E.  of  old  quarry  a-nd  on  the  same  rock  beds  of 
argillaceous  limestone.  Idle  after  1875. 

The  Allen  Cement  Company,  organized  (1872),  works  at 
their  quarry  on  Hokendaqua  creek,  1  m.  E.  of  Siegfried's 
bridge,  Northampton  county;  2  small  draw-kilns  and  2  run  of 
stone  ;  steam  power  ;  75  bbls.  per  day  of  "  Allen  "  or  "  Key- 
stone" light  yellow  cement.  Idle  after  1875.* 

In  Miffljin  county. 

A  new  dydraulic  cement  plant  is  about  being  established 
at  Milroy  in  Kishecoquillis  Valley,  on  an  outcrop  of  Tren- 
ton limestone  (1891). 

In  Centre  county. 

Hick1  s  Cement  Quarry  is  on  Logan's  branch,  south  of 
Bellefonte,  in  Spring  township,  close  to  the  Benner  town- 
ship line.  It  is  a  small  quarry  of  magnesian  limestone  (dip- 
ping 15°,  S.  38°  E.)  near  the  junction  of  lib  (Chazy)  and  lie 
(Trenton)  and  therefore  at  the  same  geological  horizon  as  the 
cement  quarries  on  the  Lehigh  near  Coplay.  Excellent  lime- 
stone beds,  150'  thick  in  all,  show  below  the  cement  works, 
dipping  40°-50°,  S.  E.  The  plant  consists  of  two  double 
kilns,  each  holding  about  200  bushels,  capacity  1600  bush, 
per  annum.  It  is  near  the  site  of  the  old  Valentine  furnace. 
(Report  T4,  1884,  pp.  314,  341.) 

*Prof.  Prime  in  his  report  D3,  1883,  p.  164,  reported  that  both  these  works 
had  been  idle  up  to  that  date,  and  added  :  "  It  must  not  be  supposed  that 
because  these  operations  have  been  apparently  unsuccessful,  that  there  is 
no  future  in  the  business  of  manufacturing  hydraulic  cement  in  this  part 
of  the  State,  on  the  contrary  the  success  of  the  Coplay  Cement  Co.  shows 
what  perseverance  under  difficulties  can  and  does  accomplish.  Of  course, 
the  composition  of  some  of  these  cement-stone  beds  is  far  more  favorable 
to  the  manufacture  of  cement  than  that  of  others,  but  all  may  be  more  or 
less  profitably  utilized  by  careful  intermixture.  There  is  no  reason  why 
the  manufacture  of  hydraulic  and  Portland  cement  should  not  be  slowly 
and  surely  extended,  not  only  by  rendering  this  portion  of  the  State  free 
from  foreign  competitors,  but  actually  rivalling  these  in  many  of  the  West- 
ern markets  on  account  of  the  excellence  of  the  product  and  the  cheapness 
of  freights." 


LIMONTTE   MINES   NEAR  THE  TOP   OF   II.  341 


CHAPTER  XXX. 

Limonite  mines  near  the  top  of  II. — Ir  onion  in  LeUigli  ; 
Moselem  in  Berks  ;  Cornwall  in  Lebanon  ;  Mt.  Pleasant 
in  Franklin  /  Henrietta  in  Blair. 

Along  the  northern  edge  of  the  limestone  belt  of  the  Great 
Valley  in  Lehigh  county,  that  is,  not  far  from  the  foot  of 
the  low  hills  which  mark  the  southern  limit  of  the  slate 
belt,  and  therefore  along  the  outcrops  of  the  top  beds  of 
the  magnesian  limestone  formation,  lie  a  range  of  limonite 
mines  of  considerable  age  and  size,  one  of  which  is  the 
famous  old  Balliet  mine,  now  known  as  the  fronton  mine. 

It  is  difficult  to  make  a  clear  statement  of  the  geological 
situation  of  the  damourite  slates  which  have  furnished  the 
material  for  these  pots  of  white  and  black  clays,  brown 
hematite  iron  ore,  and  oxide  of  manganese  ;  but  they  seem 
to  be  transition  beds  between  the  magnesian  limestones  of 
II  and  the  purely  argillaceous  slates  of  III ;  and  it  may  be 
said  without  much  fear  of  error  that  they  are  the  repre- 
sentatives of  the  Trenton  formation,  or  of  the  lower  part 
of  it,  because  Trenton  fossils  mark  the  range  of  argillaceous 
non  magnesian  limestone  beds  which  is  traceable  from  the 
cement  quarries  at  Coplay  on  the  Lehigh  to  and  behind  the 
Ironton  mine,  that  is  between  the  ore  pit  and  the  slate  hills. 

How  the  Utica  black  slate  formation  (Z77a)is  connected 
geologically  with  the  black  clays  of  the  mines  it  is  not  easy 
to  say ;  for  this  formation  has  no.  conspicuous  outcrops 
along  the  Great  Valley,  but  only  manifests  its  presence  here 
and  there  at  long  intervals  between  the  Delaware  and  Po- 
tomac, and  seems  to  be  merely  a  part  of  those  passage  beds 
from  the  magnesian  limestones  of  II  up  to  the  clay  slates 
and  roofing  slates  of  III  which  are  so  admirably  and  re- 
peatedly exposed,  standing  vertical,  in  the  bluffs  of  the  ox- 
bow bends  of  the  Conodogwinnet  in  Cumberland  county. 


342  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

Some  of  these  mines  are  close  up  to  the  edge  of  the  slate 
(III) ;  others  are  at  a  distance  from  it  of  several  thousand 
feet,  and  ought  to  be  at  considerable  depths  below  the  slate 
in  the  geological  column. 

Beginning  with  the  first  mines  west  of  the  Lehigh,  on  the 
line  of  the  Ironton  railroad,  we  have,  near  Egypt,  and  2  m. 
W.  of  Coplay  :— 

P.  Steeple's  three  abandoned  excavations ,  1600' long.  The 
west  end  of  the  west  one  is  £  m.  from  the  edge  of  the  slate 
belt ;  and  yet  on  its  south  side  is  a  large  bank  of  the  Hud- 
son river  slate  (III6.)  with  a  small  quantity  of  Utica 
black  slate  (Ilia.)  on  the  dump.  In  the  middle  pit  a  little 
black  and  red  clay  on  N".  side,  and  slate  in  several  places. 
It  looks  as  if  it  were  a  deposit  of  surface  ore  in  gravel  over- 
lying slates  of  Ilia  and  possibly  III5.  Blue  and  black 
clay  (Ilia  decomposed? )  was  struck  half  way  down  shafts 
sunk  in  middle  pit,  and  little  or  no  ore  found  (D2,  46.)* 

D.  StecMe1  s  two  abandoned  pits  in  a  parallel  line  with 
the  last,  1000'  distant  to  south  ;  gravel  ore. 

J.  Ritter's  mine,  west  of  the  last,  and  only  800'  from  the 
edge  of  the  slate  belt  (as  drawn  on  the  large  map  of  Report 
D2),  is  800'  long  by  500'  wide  ;  abundance  of  black  clay  at 
its  south  end  in  both  E.  and  W.  walls,  and  just  below  the  sod  ; 
just  under  the  black  (and  also  east  of  it)  an  abundance  of 
white  and  pinkish  c\ay  ;  line  of  color  sharply  defined  ;  com- 
position the  same,f  dip  different  (black  N.  W.  white  S.  W.) 
but  this  may  be  due  to  folding  and  settling  when  the  sup- 

*It  must  be  kept  always  in  mind  that  the  slate  belt  once  extended  over 
the  limestone  belt  These  gravel  banks  are  on  two  sides  of  a  shallow  vale 
descending  eastward,  and  they  are  the  remnants  of  a  much  more  extensive 
drift  deposit,  the  main  body  of  which  has  been  swept  away  in  the  erosion 
of  the  vale. 

f  Analysis  of  "white  clay"  (1),  and  "yellow clay "'  (2)  by  I.  R.  Shimer  of 
Lafayette  College,  and  of  "yellow  clay"  (3)  by  A.  S.  McCreath  are  given  in 
Report  D,  1874,  pp.  13  to  33.  The  yellow  clay  is  used  as  ochre  for  paint.  In 
the  range  of  limonite  mines  along  the  base  of  the  South  Mountain  between 
Easton  and  Bethlehem  the  miners  call  the  White  clay  "hill  clay "  and 
ceased  to  look  for  ore  when  they  struck  it,  and  are  careful  not  to  go  through 
it  for  fear  of  being  drowned  out.  It  is  a  working  hypothesis  that  as  the 
damourite  slates  were  turned  into  clay  they  were  able  to  play  the  part 
of  an  impervious  water-bearing  stratum,  upon  which  iron  solutions  re- 
mained tanked  and  threw  down  their  limonite.  (Prime,  in  D.  p.  14.) 


IRONTON   LIMONITE   MINES.  343 

porting  floor  of  limestone  was  dissolved  away. — IS".  B. 
Here  there  is  a  layer  of  limonite  8"  to  13"  thick  which  cut 
through  both  black  and  white  clay.* 

The  Ir onion  mine,  2000'  long  by  800'  broad  and  90'  deep 
(in  1878)  is  owned,  at  the  east  end  by  the  Balliet  heirs,  in 
the  middle  by  the  Balliet  brothers,  and  at  the  west  end  by 
the  Ironton  company  /  worked  since  1837,  when  the  ore 
showed  itself  above  the  surface  of  the  soil ;  limestone  beds 
at  various  points  deepening  from  east  end  to  west  end  ; 
walls  mostly  plastic  (damourite)  clays,  mostly  iron-yel- 
lowed, much  white,  some  manganese,  pink  or  red,  also 
masses  of  (Utica)  black  at  N.  W.  end,  in  center,  and  at 
east  end. 

The  black  clay  masses,  once  continuous  and  now  sepa- 
rated by  mining  the  ore,  contains  itself  a  curious  ball  ore 
(siderite,  carbonate  of  iron)  like  that  so  common  in  the 
coal  measures,  but  too  little  of  it  and  too  scattered  to  be 
worth  mining.  Native  copper  also  occurs  in  the  black 
clay,  in  small  filiform  pieces,  having  been  reduced  to  na- 
ture by  carbon  in  the  clay.  The  black  clay  deposit  varies 
from  V  to  10',  and  sometimes  swells  to  20'.  It  contains 
graphite,  which  makes  its  genesis  from  the  Utica  slate  still 
more  probable. f 

Ore  occurs  in  various  parts  of  the  mine,  mostly  under  the 
black  clay,  especially  at  the  west  end,  in  the  central  deep 
pit,  and  along  the  northern  side.J 

*This  remarkable  fact  is  of  great  importance,  but  only  increases  the  ob- 
scurity under  which  the  origin  of  our  limonite  deposits  lie.  If  the  original 
undeconi posed  black  and  white  slates  were  of  the  same  age  and  conforma- 
ble, the  ore  must  be  of  that  age  ;  if  the  clays  are  of  different  ages  the  segrega- 
tion of  the  ore  layer  must  have  occurred  later.  The  ore  of  this  curious  layer 
yielded  to  McCreath  :  Iron,  39.3;  mang.,  0.006  ;  sulp.,  0.008 ;  phos.,  1.27;  insol., 
28.20.  The  ore  from  the  pit  floor :  Iron,  47.7  ;  mang.,  2.97  ;  sulp.,  0.05  ;  phos., 
0.33  ;  insol.,  12.60.  Crane  Iron  Co.'s  analyses  are  given  on  p.  46,  D5- 

f  Analysis  of  black  clay  (called  "blue  ochre")  by  Dr.  Genth  :— Loss  by 
ignition  in  closed  crucible  (water),  4.84  ;  ditto  in  open  crucible  (graphite), 
4.26;  quartz,  44.50;  combined  silica,  26.25;  alumina,  with  traces  of  ferric 
oxide,  17.95  ;  magnesia,  0.94 ;  alkalies  etc.  (not  determined),  1.26  =  100. 
(D,  p.  32.) 

$  The  quantity  of  manganese  in  the  ore  is  surprising.  An  average  sample 
of  ore  taken  from  the  Ironton  RR.  Co.'s  .wharf,  analyzed  by  McCreath,  gave : 
Iron,  26.40;  manganese,  17.65;  sulphur,  0.01;  phos.,  0.09;  insol.,  21.86.  (D243.) 


344  GEOLOGICAL   SURVEY   OF  PENNSYLVANIA. 

Local  beds  of  black  oxide  of  manganese  has  occurred 
twice  ;  one  in  1872  over  a  part  of  the  limonite  yielded  a 
good  many  tons ;  another  in  1875,  in  the  deepest  part  of 
the  mine,  just  over  the  limestone  floor,  yielded  several  hun- 
dred tons  ;  just  over  it  a  red  clay  separated  it  from  the 
overlying  limonite.* 

P.  Brown's  mines,  70'  deep,  is  only  100'  from  the  east 
end  of  the  great  Ironton  mine,  and  lies  exactly  in  the  center 
of  the  trough ;  ore-breast  30'  to  40'  high  at  W.  end,  con- 
sisting almost  entirely  of  pure  ore,  with  intermingled 
damourite  slate  and  clay  and  more  or  less  allophane.f 

White  damourite  clay,  in  the  east  wall,  under  the  in- 
cline-plane contains  lignite  (carbonized  wood)  and  fossil 
leaves  ;  a  beecTi  nut  has  been  found  in  it ;  of  course  of  post- 
tertiary  age.  The  clay  -lies  on  the  ore  and  is  a  deposit  of 
human  age  ;  whatever  the  age  of  the  ore  may  be  ;  but  proba- 
bly both  are  of  the  latest  geological  age,  and  in  fact  de- 
posits in  a  cavern,  which  has  lost  its  roof.  Black  clay 
(Uticaf]  overlies  the  ore  thickly  in  the  N.  wall,  but  has 
been  swept  away  from  the  south  wall.:}: 

The  limestone  floor  beds  dip  S.  E.  and  N.  W.,  in  such  a 
way  as  to  make  a  synclinal  basin  or  trough,  which  runs 
east,  south  of  Hitter's  mine  ;  and  this  trough  holding  the 
ore  mass  and  sinking  westward  towards  the  head  of  the 
cove,  makes  the  ore  mass  greater  and  deaper  westward. 
There  are  signs  of  exhaustion,  unless  ore  be  found  W.  of 
the  road  to  Balliettsville  ;  and  eventually  in  any  case  in 
that  direction  the  edge  of  the  slate  belt  will  cut  the  ore 

*  Mostly  shipped  to  Johnstown  for  spiegeleisen.  Analysis  of  average 
specimen  by  McCreath,  Mang.  binox.,  77.96;  mang.  ox.,  4. 32;  ferric  oxide, 
3.66  ;  silica,  4.84  ;  alumina,  0.71 ;  baryta,  0.15;  lime  0.77  ;  magnesia,  0.24;  soda, 
0.37  ;  potassa,  3.04  ;  cobalt  ox.,  0.39 ;  nickel  ox.,  trace;  copper  ox.,  trace ;  phos. 
acid,  0.15;  water,  3.98.  A  picked  specimen  gave  mang.  binox.,  84.88-fox. 
3.77;  cobalt  ox.,  1.68;  lime,  1.90;  mang.  0.79;  soda,  0.19;  pot.,  3.50;  water,  4.38 
(D2,  p.  42.) — Manganese  appeared  at  the  surface  near  the  Big  Spring,  W. 
of  Trexlertown.  (H.  D.  Rogers,  1858.) 

f  A  very  fine  white  and  sky  blue  stalactitic  hydrous  silicate  of  alumina, 
vitreous  or  resinous,  waxy  or  pearly,  found  in  masses  at  the  Cornwall 
mine  ;  at  Jones'  mine  near  Morgan  town,  Berks  county.;  at  the  Friedensburg 
zinc  mines  ;  and  here. 

\  For  mining  prospects  and  analysis  see  D2,  p.  44. 


IRONTON   LIMONITE   MINES.  345 

mass  off,  for  "at  no  point  hitherto  has  the  ore  been  fol- 
lowed in  under  the  slate." 

Ironton  is  at  the  W.  end  of  the  mine,  and  the  cove  of 
limestone  is  made  by  the  projection  E.  of  a  sharply  pointed 
I>rong  of  slate  (III)  more  than  a  mile  long  ;  the  real  syn- 
clinal of  the  district ;  the  trough  in  the  cove  being  a  mere 
local  roll,  although  a  large  one,* 

The  Ironton  RR.  CoSs  Kennel  mine,  and  the  H.  Mickley 
abandoned  and  exhausted,  lie  to  the  south  of  the  slate 
prong  and  1000'  from  it.  Damourite  white  clay  and  Utica  • 
black  clay  in  the  latter.  The  former  mostly  yellow  plaster 
clay,  but  some  white,  and  a  little  black  clay  overlying  the 
white;  a  little  ore  visible  in  contact  with  and  under  the 
black  clay.^ 

The  great  Siegersville  limestone  cove,  further  south,  con- 
tains many  mines,  none  of  them  less  than  half  a  mile  from 
the  edge  of  the  slate  belt,  and  most  of  them  a  mile  or  two 
from  it.  They  are  all  described  in  D2,  pp.  34  to  39  ;  many 
abandoned;  some  mere  wash  ore;  most  of  them  showing 
white  clay. 

8.  Sieged s  mine  at  Siegersville,  worked  at  E.  end.  has  a  6 
inch  ore  layer  under  the  sod  ;  then  12'  barren  ;  under  which 
ore  bed  2'  to  4' ;  ore  in  shaft  in  floor  reported  40'  thick  ; 

*But,  as  an  illustration  of  the  difficult  geology  of  the  limestone  belt,  ob- 
serve on  the  map  the  long  (N.  E.  and  S.  W.)  line  of  observed  limestone 
dips  obliquely  crossing  the  point  of  the  slate  prong,  and  reading  only  32°,  23°, 
28°,  320,  120  (at  the  point),  11°,  22°,  25°,  32°,  24°,  8.  JE.  Even  the  violent 
theory  of  a  collapsed  overthrown  and  flattened  down  synclinal  will  not  ex- 
plain so  puzzling  an  exhibition.  It  almost  justilies  the  theory  of  the  non- 
eonformability  of  III  upon  II.  To  increase  the  embarassment  there  are  dips 
of  N.  E.  17°  and  28°  in  the  slate  pronrj  along  the  high  road.  (See  the  fine 
colored  map  of  the  Ironton  mines  in  D2,  pocket.) 

t  A  remarkably  beautiful  colored  geological  sheet  map  of  the  Ironton 
group  of  mines  and  slate  prong  which  separates  them  may  be  found  in  a 
pocket  to  Report  D2,  1878.  The  limestone  in  the  mine  floors,  the  ore  masses, 
the  red,  white,  yellow,  and  red  clays,  and  the  undecomposed  slates  are  all 
distinguished  by  separate  colors.  The  depths  are  shown  by  contour  lines, 
which  are  also  extended  over  the  whole  sheet.  It  is  a  rarely  perfect  exhi- 
bition, on  a  scale  of  300' :  1"  of  an  unusually  complete  piece  of  difficult  field 
work.  It  is  dated  1875,  and  is  the  work  of  Mr.  Ellis  Clark,  Jr.,  aid  to  Prof. 
Fred.  Prime,  Assistant  Geologist  in  charge  of  the  Survey  of  the  Lehigh 
region. 


346  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

much  lump  ore  and  blood  red  clay  ;  in  one  place  limestone 
over  the  clay,  the  limestone  "thorough!}7  permeated  by 
damourite.* 

Jas.  Kline's  mine,  at  Orefield,  £m.  S.  of  Siegersville,  is 
within  £  m.  of  the  N".  edge  of  the  long  syrcelinal  slate  prong 
which  runs  out  eastward  four  miles,  eastward  N.  of  Wen- 
nersville.  Most  of  the  ore  is  extracted.  AtN.  E.  corner  soil 
20'  deep  ;  then  red  ore  bearing  clay  10',  then  yellow  and 
white  clays  streaked  with  ore  ;  very  little  lump  ore  found. 
Damourite  slate  sticks  so  closely  to  much  of  the  ore  that  it 
cannot  he  separated  by  washing.  White  clay  both  above 
and  beneath  the  ore.  At  W.  end,  soil  M^feet ;  then  all 
white  clay  down  to  standing  water,  with  a  good  deal  of 
only  partially  decomposed  damourite  slate  in  the  clay. 
Yield  of  mine  has  been  great. 

B.  Weaver's  mine,  I  m.  E.  of  Orefield  and  Guthsville, 
and.  just  on  the  north  edge  of  the  slate  prong ;  40'  deep  ; 
near  top  damourite  slate  with  white  ore  clay  underneath  ; 
atN.  end  damourite  slate  holding  thin  strings  of  ore,  but 
the  ore  mass  is  beneath  it ;  slate  resembles  No.  III. 

The  Thomas  I.  Go.  and  Crane  I.  Go.  and  D.  A.  Guth1  s 
and  the  two  Wanner  mines  range  eastward  along  the  north 
side  of  the  slate  prong.  They  have  furnished  large  quanti- 
ties of  ore,  but  are  exhausted.  At  Guth's  mine  limestone 
is  seen  dipping  S.  E.  towards  and  under  the  slate  prong  ; 
but  the  Utica  slate  (?)  seems  to  dip  N.  W. 

Toward  the  end  of  the  slate  prong  are  six  mines  :  Kratzef  s, 
Jobsfs  (2),  and  Scherer' s,  on  the  north  edge  of  the  slate 
prong  ;  Marck's  at  the  extreme  point ;  and  Barber  and  Al- 
ney' son  the  south  edge  near  the  point.  In  these  are  seen 
pinkish  damourite  slate,  and  sometimes  a  black  slaty  rock 
which  may  stand  for  the  Utica.  The  whole  range  are 
abandoned. 

In  the  next  limestone  cove  3  m.  IS".  W.  of  Trexlerville,  there 
are  about  15  mines,  mostly  abandoned^  all  but  one  within 

*This  either  shows  a  cavern  deposit  of  clay,  or  proves  the  decomposition 
of  damourite  layers  far  down  the  stratification  beneath  an  insoluble  roof 
of  limestone  beds. 


LIMONITE   MINES   NEAR   THE   TOP   OF   II.  347 

i  m.  of  the  edge  of  the  slate :— LichtenwallnerX  Loros' 
(two),  Stein's  (two),  Moyer  s,  Steininger's  (two),  Scholl 
&Co.'s,  Miller's  (two),  and  Haines'  and  Smith's  (Schlong's), 
the  last  two  in  front  of  the  east  point  of  the  slate  prong 
which  shuts  in  the  cove.* 

In  the  centre  of  the  Cove  a  mile  from  the  slate  edge 
Krsemlich  &  Lichtenwallner'smine  (D.  p.  42),  50' deep,  not 
worked  since  1873,  has  its  ore  mass  lying  on  horizontal 
blue  Limestone,  probably  the  flat  crown  of  the  anticlinal  of 
the  cove.  There  is  evidently  a  large  amount  of  damourite 
slate  and  white  clay  underlying  the  ore  and  in  some  places 
inside  of  it.  If  we  could  tell  the  shape  of  the  arch,  this 
would  settle  the  question  whether  or  not  some  of  the  Le- 
high  limonites  were  made  from  damourite  sub-formations 
in  the  body  of  No.  II.  But  if  the  arch  is  flat,  or  subdi- 
vided by  a  synclinal,  the  damourite  clays  in  this  mine 
may  also  belong  to  the  slates  at  the  top  of  II. 

At  the  head  of  the  next  shallow  limestone  cove  and  close 
against  the  edge  of  the  slate  belt,  l^m.  N.  W.  of  Breinigs- 
ville,  is  Fr.  Breinig*  s  large  exhausted  mine,  50'  deep  ;  but 
a  small  pit  on  the  east  of  it  was  still  worked  in  1874  ;  ore 
streaks  in  damourite  slate  and  white  and  yellow  clays  ; 
ore  and  clays  pitching  18°  to  25°,  S.  80°  E.  away  from  the 
slate  belt!  And  yet  a  glance  on  the  large  sheet  map  of  D2 
is  sufficient  to  show  a  bridge  of  slate  (III)  thrown  across 

*In  Lichtenwallner's  pits  (one  40'  deep)  the  ore  lies  both  on  and  under 
white  clay  over  damourite  slate  ;  blue  limestone  reported  at  the  bottom  of 
a  well  130'  deep.— At  Loros's  mine  a  gravel  of  clay,  quartz  and  slate  (all  in 
small  pieces)  15'  deep  covered  the  west  end. — Stein's  oldest  mine  must  have 
had  a  great  output.  The  other  leased  to  the  Thomas  I.  Co.  shows  no  slate  ; 
the  ore  lies  in  and  over  white  and  pink  damourite  clays  47'  deep  ;  limestone 
at  40'  in  one  place  dips  42°,  S.  41°  E.  (top  layers  drab  slaty  4',  laying  on 
common  blue  limestone  water  worn);  ore  clays  over  the  limestone  dip  42°, 
S.  40°  E.  A  hole  10"  square  in  the  floor  drains  the  mine  into  some  un- 
known cavern. — Moyer'' s,  a  new  stripping  (1875).  Steininger's  old  mine  ; 
very  productive ;  600' x20'  deep  ;  exhausted.  The  other  leased  by  Lani- 
gan,  25'  deep ;  ore  in  damourite  slate  overlying  white  clay,  dipping  22°,  S. 
40°  E.  In  one  place  under  12'  of  solid  white  clay  is  ore  6',  then  clay  12'. — 
Scholl  &  Co. 's  ore  in  rolling  clay ;  general  average  dip  10°,  S.  5°  E.;  local 
dips,  to  S.  W.  (one  of  them  55°,  S.  25°.  W);  output  25 tons  per  day  (1883)— 
Miller'1  s,  abandoned,  described  by  Rogers  (1858)  as  ore  interstratified  irre- 
gularly with  clay. — Haine's,  abandoned — Smith's,  40'  deep,  described  by 
Rogers  as  Schlong's,  in  damourite  slate. 


348  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 


LIMONITE   MINES   NEAR  THE  TOP   OF   II.  349 


Section  along  Cornwall  Railroad 
from  Isebanon  to  Miners' Village. 


Section  acraalSig  Hill  combined  wdk  Seclwn  cdang  Furnace  creek. 

them  Iraf  dUUrla  itt  relaiiantkip  io  Creek  section. 


CnvyXU 


§  ORi-MA5S 

Seal*.  rtHical  and  Jinriifntal  alUa .     &OO fe*t,  lo  4  inch. 


"""  J.U& 


350  GEOLOGICAL   SURVEY    OF   PENNSYLVANIA. 

the  limestone  of  the  cove  (II)  and  isolating  the  head  of  the 
cove  as  an  enclosed  limestone  circus  in  the  body  of  the 
slate  belt.  This  abnormal  dip  must  therefore  be  a  sag  of 
the  decomposed  ore-mass  into  some  cavern  in  the  limestone. 

The  Trexlertown  Copperas  mine  deserves  mention  here 
for  the  bore  hole  records  preserved  in  Rogers'  Geol.  Pa., 
1858,  p.  265 ;  1  m.  W.  of  Trexlerville  (£  m.  N.  E.  of  Brein- 
igsville) ;  worked  in  1836-1840  ?  by  N.  Whitely. 

Boring  No.  1  recorded :  Clay  and  gravel,  30';  iron  ore, 
4|';  clay.  7£';  black  clay,  2';  sulphur  et  of  iron  (pyrites],  12'; 
iron  ore,  5'. 

Boring  No.  2:  clay  and  gravel,  15';  iron  ore,  1';  clay, 
15':  slate,  5';  clay,  6';  pipe  ore  in  clay,  9' /  clay,  4£'. 

Boring  No.  3  :  clay,  14';  iron  ore  in  clay,  8';  iron  ore,  9'; 
clay,  3';  copperas  earth,  2';  copperas  in  black  clay,  2';  cop- 
peras in  white  clay,  2';  brown  clay  and  iron  ore,  8';  solid 
iron  ore  (pipe?),  2';  clay,  8'. 

Manganese  oxide  appeared  in  the  west  wall.  The  slate 
mentioned  in  No.  2,  was  made  somewhat  gypseous  by  the 
reaction  of  the  sulphate  of  iron  on  its  lime  element.  "The 
origin  of  this  large  deposit  of  sulphuret  of  iron,"  says  Mr. 
Rogers,  "is  to  be  traced  probably  to  a  small  shallow  bed 
of  Matinal  [Utica]  black  slate  which  appears  to  have  rested 
on  the  limestone  and  to  have  undergone  disintegration." 
But  if  this  opinion  is  correct  we  may  extend  the  expla- 
nation to  most  of  the  other  limonite  mines  in  the  central 
area  of  the  limestone  belt. 

The  Moselem  mine  in  Berks  Co. 

This  famous  old  mine,  5  m.  W.  of  Kutztown,  is  within 
1000'  of  the  edge  of  the  slate  belt,  and  corresponds  exactly 
to  the  great  Ironton  mine.  The  ore  was  reached  at  first  by 
shafts  through  surface  stuff  20'  to  40'  deep.  Immense 
quantities  of  good  ore  were  mined  from  nests  and  irregu- 
lar layers  varying  from  V  to  8'  thick  ;  some  of  it  bluish  and 
slightly  manganesian.  Limestone  beds  in  the  ridge  south 
of  the  mine  dip  northward,  as  they  should,  under  the  ore, 
and  (if  continued]  under  the  slate  belt.  Large  quantities 
of  dark  chept,  some  of  them  hundreds  of  pounds  inweightr 


THE    MOSELEM    MlNE.  351 

lay  scattered  over  the  soil.  (Rogers'  Geol.  Pa.,  1858,  p.  226.) 
In  1878  the  mine  was  surveyed  by  A.  P.  Berlin,  in  common 
with  the  whole  valley  between  the  Schuylkill  and  the  Lehigh 
county  line.  It  was  then  2000'  long  and  100'  deep,  with 
five  inclined  planes.  (See  Fig.  1,  on  plate  VIII.)* 

It  is  certainly  a  surprising  circumstance  that  this  great 
Moselem  deposit  should  stand  alone  ;  that  nothing  like  it 
appears  for  so  many  miles  along  the  edge  of  the  slate  belt  in 
Berks  and  the  counties  to  the  west  of  it.  One  is  tempted 
to  suspect  great  local  variations  in  the  thickness  or  rich- 
ness of  the  upper  damourite  slate  formation.  Or  perhaps 
a  mechanically  produced  non-conf or  mobility  has  shoved 
the  damourite  slates  beneath  the  slate  belt  edge.  But 
more  probably  the  only  and  sufficient  explanation  is,  that 
only  here  and  at  Ironton  and  a  few  other  places  caverns 
have  been  eroded  to  receive  the  iron  drainage.  Vague  as 
this  suggestion  may  seem  it  is  borne  out  by  such  exhibi- 
tions as  the  Pond  banks  of  Franklin  county  ;  and  by  the 
cavern  deposit  of  Penns  valley  in  Centre  county,  to  be  de- 
scribed in  another  chapter. 

The  Cornwall  mine. 

This  summary  description  of  the  Lower  Silurian  Forma- 
tion No.  II  would  be  incomplete  without  a  special  mention 
of  one  of  the  most  important  mines  in  Pennsylvania,  the 
great  magnetic  iron  ore  mine  of  Cornwall,  in  Lebanon  county, 
unique  in  its  character,  standing  alone  in  the  geology  of 

*Fig  2  on  the  same  plate  is  a  reduction  from  Sheet  XIV,  of  the  great  topo- 
graphical map  of  the  South  Mountains  (Reading  and  Durham  highlands) 
published  in  the  Atlas  to  Report  DH,  Vol.  2,  1883.  The  survey  of  the  lime- 
stone belt  was  made  by  Mr.  A.  P.  Berlin  in  1878.  The  small  portion  of  it 
given  in  Fig.  2  illustrates  the  flatness  of  the  limestone  belt;  the  steep  hill- 
side edge  of  the  slate  belt,  through  small  gorges  in  which  its  back  drainage 
issues  upon  the  limestone  belt;  and  the  close  proximity  of  the  great  limo- 
nite  deposit  to  this  outcrop  wall.  At  the  the  east  edge  of  the  figure  the 
reader  will  notice  the  normal  36°  northwest  dip  of  the  limestone  descend- 
ing beneath  the  slate  belt  in  the  ravine;  also  northwest  and  southeast  (anti- 
clinal roll)  dips  in  the  quarry  east  of  the  ravine ;  also  an  18°  northwest  dip 
in  the  little  quarry  west  of  the  ravine;  and  other  northwest  dips  around 
Leibensperger's ;  so  that  the  geological  place  of  the  ore  slates  is  unmistakably 
at  the  top  of  II  under  the  slates  of  III,  with  no  evidence  of  non-conform- 
ability  between  the  two  formations. 


352  GEOLOGICAL   StJRVEY   OF   PENNSYLVANIA. 


THE    CORNWALL    MINE. 


354  GEOLOGICAL   SURVEY    OF   PENNSYLVANIA. 

the  State,  arid  pouring  year  after  year  its  flood  of  wealth 
into  the  business  world.  Worked  for  more  than  fifty  years, 
it  shows  no  sigh  of  exhaustion  ;  on  the  contrary,  its  annual 
output  continually  swells  in  volume. 

Three  hills  of  ore  three  hundred  feet  high,  are  ranged  in  a 
line  a  mile  long  and  a  third  of  a  mile  wide.  Walls  of  solid 
ore  80  feet  in  vertical  height  are  stoped  down  by  dyna- 
mite ;  and  the  fragments,  broken  up  to  portable  sizes,  are 
loaded  in  cars  and  distributed  to  the  iron  furnaces  of  the 
region.  A  floor  of  the  solid  iron  ore  at  water  level  conceals 
an  underlying  ore-mass,  into  which  test  holes  have  been 
bored  varying  in  depth  from  50  to  300  feet.  A  great  vol- 
canic trap-dyke,  like  the  half  of  a  cup,  supports  the  ore- 
mass  at  its  northern  edge,  and  has  been  proved  by  some  of 
the  bore-holes  to  be  its  floor.  Along  the  southern  edge  runs 
one  of  the  few  great  faults  of  the  State,  limiting  the  ore- 
mass  on  that  side.  Against  this  fault  descends  (northward) 
at  a  gentle  slope  the  Mesozoic  beds  of  northern  Lancaster, 
their  sheared-off  edges  making  the  southern  side  of  the  cup 
which  holds  the  ore-mass. 

It  is  this  unusual  occurrence  of  Mesozoic  red  sandstone 
faulted  against  the  limestone  formation  of  the  Great  Valley, 
with  an  outburst  of  ancient  lava  rising  through  the  crack  thus 
produced  and  making  its  way  sidewise  between  the  limestone 
strata,  lifting  them  and  holding  them  isolated,  as  in  a  vat 
in  a  chemical  laboratory — it  is  this  unusual  combination  of 
circumstances  which  has  given  its  unique  character  to  the 
Cornwall  iron  mine.  The  mine  has  been  a  puzzle  to  geolo- 
gists ;  and  a  satisfactory  explanation  of  it  has  been  only 
recently  obtained  by  a  laborious  research  upon  the  ground. 

It  is  now  made  evident  that  the  whole  ore-mass  was  orig- 
inally a  set  of  lime-shale  strata  belonging  to  the  very  top 
of  Formation  No.  II,  which  we  may  call  the  passage  beds 
between  No.  II  and  No.  III.  These  beds,  held  between 
the  two  walls  of  Trap  and  Trias,  have  been  attacked  by  hot 
acid  waters  flowing  into  them,  dissolving  away  the  carbon- 
ates of  lime  and  magnesia,  and  leaving  behind  in  a  concen- 
trated mass  the  insoluble  silicates  and  hydrated  peroxide 
of  iron,  converted  much  of  it  into  the  magnetic  oxide. 


THE    CORNWALL    MINE.  355 

The  whole  mass  of  ore  is  distinctly  stratified,  and  shows 
the  process  of  concentration.  The  original  insoluble  matters 
in  the  lime-shale  still  remain  in  the  ore.  The  stratification 
of  the  ore-mass  is  perfectly  regular ;  but  almost  unchanged 
white  crystalline  limestone  beds  lie  interstratified  in  the 
midst  of  it,  showing  that  some  of  the  original  strata  had  a 
mineral  composition  not  susceptable  to  a  change  into  ore. 
These  limestones  lie  in  their  original  places  among  the  other 
strata  which  have  been  changed  into  ore.  But  they  have 
been  subjected  to  merely  enough  change  to  convert  them  into 
an  inferior  kind  of  crystalline  marbie.  The  rest  of  the  ore 
strata  were  no  doubt  first  charged  with  hydrated  peroxide 
of  iron  (brown  hematite) ;  but  the  change  went  on  one  step 
further;  the  water  was  driven  off,  and  the  oxide  of  iron  was 
crystallized  into  magnetic  iron  ore ;  still  retaining  all  the 
impurities  of  the  original  lime-shale  beds. 

The  remarkable  features  of  this  ore  mass  are  :  First,  the 
quantity  of  sulphur  which  it  contains  ;  and,  Secondly,  the 
universal  distribution  of  a  small  percentage  of  copper 
through  the  whole  mass  of  ore  ;  and  its  concentration  into 
strings  and  plates  of  native  copper  only  in  the  upper  part 
of  the  mass  where  attempts  were  made  at  one  time  to  ob- 
tain it  in  sufficient  quantities  to  make  it  marketable  ;  but  the 
richest  pockets  of  it  at  the  top  of  the  hill  were  soon  ex- 
hausted, and  none  others  have  been  met  with  lower  down.* 

*The  origin  of  the  copper,  and  of  the  sulphur  also,  has  been  connected 
with  the  outburst  of  trap,  and  also  with  the  neighborhood  of  the  Triassic 
sandstones,  but  the  subject  is  still  entirely  obscure.  Nor  is  it  of  practical 
importance,  for  all  attempts  to  mine  copper  in  Pennsylvania  have  signally 
failed.  But  to  geologists  the  question  of  the  origin  of  the  copper  in  the  Corn- 
wall ore  is  one  of  high  interest.  At  present  the  only  facts  which  we  can  bring 
to  bear  upon  it  are  those  connected  with  the  old  copper  operations  at  the  edge 
ol  the  Mesozoic  sandstone  in  Chestercounty  westof  Norristown;  and  these  are 
not  sulllciently  understood  to  throw  much  light  upon  the  subject  It  is 
remarkable  that  the  mines  near  Dillsburgin  York  county  furnish  the  same 
kind  of  copper-bearing  magnetic  iron  ore  as  that  at  Cornwall ;  that  they  are 
surrounded  by  Mesozoic  red  sandstone  near  its  present  northern  edge;  and 
that  outbursts  of  trap  similar  to  the  trap  enclosure  at  Cornwall  are  also  in 
contact  with  the  Dillsburg  ore.  Similar  ores  are  also  mined  on  Fritz's  is- 
land in  the  Schuylkill  near  Reading,  and  at  Boyertown  and  at  Seitzholtz- 
ville  further  east  in  Berks  county,  where  copper  and  trap  again  accompany 
the  ores.  All  this  suggests,  although  it  does  not  prove,  that  the  copper  has 
come  in  some  form,  perhaps  as  vapour,  with  the  fluid  lava  from  the  interior 


350  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

I  do  not  propose  to  repeat  in  this  summary  of  the  geol- 
ogy of  the  State  the  very  full  description  of  the  Cornwall 
mine  published  as  a  separate  memoir  in  the  Annual  Report 
of  the  Survey  for  1885,  pages  491  to  565,  with  maps  and 
sections  and  page,  plate  diagrams,  showing  stope-faces, 
the  structure  and  the  construction  of  the  ore-mass.  In 
lieu  of  verbal  descriptions  I  give  the  more  important  of 
these  illustrations,  greatly  reduced,  but  legible  enough  to 
make  the  whole  thing  comprehensible.* 

The  geological  situation  of  the  Cornwall  mine  and  its 
railway  connections  with  Lebanon  are  shown  by  Fig.  3  on 
Plate  IX. 

The  reason  for  placing  it  geologically  at  the  top  of  II  in- 
stead of  at  the  bottom,  although  it  is  on  the  southern  in- 
stead of  the  northern  edge  of  the  limestone  belt,  is  made 
clear  by  Fig.  1  on  Plate  IX,  which  represents  a  cross-section 
of  the  belt  (looking  east)  from  the  edge  of  the  slate  belt  to 
the  edge  of  the  Trias  country.  The  vertical  rise  of  the  top 
beds  of  II  at  Lebanon,  their  flattened  rolls  across  the  belt, 
and  their  descent  at  Cornwall,  require  no  commentary,  f 

of  the  earth  ;  and  it  is  possible  that  the  sulphur  accompanied  it  On  the 
other  hand  we  have  copper  shales  in  the  Devonian  formation  of  the  northern 
counties  of  the  State  a  hundred  miles  from  any  trap,  and  several  miles  above 
the  plutonic  floor.  But  one  of  the  most  conclusive  proofs  that  the  Cornwall 
and  Dillsburg  copper  has  no  necessary  connection  with  either  the  Trap  or 
the  Trias  is  found  in  the  facts  mentioned  on  a  previous  page,  namely,  that 
similar  leaves  and  strings  of  native  copper  are  found  in  stripping  the  black 
clay  from  the  limonite  ore  mass  at  Ironton,  which  is  not  at  all  magnetic,  has 
no  trap  near  it,  and  is  in  fact  a  simple  leaching  from  the  upper  damourite 
slates  at  the  edge  of  the  slate  belt  It  looks  as  if  the  sea-water  of  that  age 
was  heavily  charged  with  soluble  salts  of  copper,  as  the  water  of  the  Medi- 
teranean  Sea  is  now.  As  for  the  abundance  of  sulphur,  it  is  only  necessary 
to  allude  to  the  many  red-short  ores  of  our  back  valleys,  far  from  any 
source  of  heat ;  but  especially  to  the  account  given  on  a  previous  page  of  the 
Copperas  mine  between  Breinigsville  and  Trexlersville  in  Lehigh  county. 

*The  reader  may  find  a  condensed  statement  of  all  the  facts,  and  a  num- 
T>er  of  their  illustrations,  in  Mr.  E.  V.  d'Invilliers'  paper  read  before  the  In- 
stitute of  Mining  Engineers  at  its  Pittsburgh  meeting,  Feb.,  1886,  and  pub- 
lished in  its  Transactions.  I  assisted  Mr.  d'Invilliers  by  a  personal  examina- 
tion of  the  mine,  and  am  responsible  for  the  theoretical  conclusions  to  which 
he  did  not  yield  an  unqalified  assent,  and  at  which  other  competent  geolo- 
gists may  demur.  Cornwall  must  continue  to  be  for  many  years  a  theme 
for  discussion. 

f  I  have  in  a  previous  chapter  described  similar  descents  of  the  slates  of 
III  along  the  south  edge  of  the  limestone  belt  in  Cumberland  and  Dauphin 


PATH.  VALLEY  MINES  IN  FRANKLIN  COUNTY.    357 

Cross-sections  of  the  ore  mass  and  trap  are  given  in  Fig. 
2,  Plate  IX,  and  Fig.  1,  Plate  XI ;  and  a  section  lengthwise 
through  the  three  ore  hills  is  given  in  Fig.  3,  Plate  IX. 

A  reduction  of  D'Invilliers'  topographical  map  of  the 
whole  mine  (in  part)  is  given  in  Plate  X.  The  most  strik- 
ing feature  of  this  map  is  the  trap  liook  at  its  eastern  end. 
I  can  imagine  no  other  explanation  for  this  most  interesting 
structure  than  that  suggested  in  the  memoir  in  the  Annual 
Report,  viz :  that  the  ore-mass  really  represents  a  body  of 
limeshales  thrown  into  a  sharp  and  deep  synclinal,  and 
that  the  out*  and  up-flowing  trap  followed  the  synclinal 
bedding.  This  south  side  of  the  synclinal  trough  was 
sheared  off  by  the  fault,  and,  therefore,  the  trap  hook  stops 
at  the  fault.  But  this  leaves  unexplained  why  the  trap 
did  not  follow  up  the  fault  to  the  present  surface,  and  pre- 
ferred rather  to  rise  sidewise  (N.)  between  the  beds. 

The  curious  tongued  structure  of  the  trap  on  the  north 
edge  of  the  Big  Hill  shown  in  Fig.  3,  Plate  XI  suggests 
that  we  are  thece  not  far  from  the  extreme  limit  of  the  trap 
ejection  upwards. 

The  outcropping  unchanged  limestone  beds  in  the  body 
of  the  ore  mass  are  shown  in  Fig.  2,  Plate  XI. 

Patli   Valley  mines  in  Franklin  County. 

Path  valley  is  an  anticlinal  limestone  cove  in  the  north- 
western side  of  Franklin  county,  extending  for  about  ten 
miles  in  a  1ST.  E.  and  S.  W.  direction  along  the  eastern  base 
of  that  portion  of  the  North  mountain  locally  known  here 
under  the  name  of  the  Tuscarora  mountain.  It  ends  on 
the  S.  W.  in  a  cove  between  this  mountain  and  an  outlying 
spur  known  as  Bear  Knob,  while  to  the  N.  E.  the  anticlinal 

counties.  Another  occurs  in  Lebanon  county  east  of  Cornwall.  But  the 
most  extraordinary  instance  is  to  be  seen  at  Reading,  where  a  north  and 
south  belt  of  III  is  colored  on  d'Invilliers'  map  as  intervening  between  the 
Schuylkill  and  the  mountains  back  of  Reading.  How  the  structure  here  is 
to  be  explained  I  can  only  conjecture  by  supposing  a  westward  slip  of  the 
valley  rocks  from  over  the  mountain  gneiss.  At  the  beginning  of  Chapter 
XXVI,  I  have  described  the  east  dips  of  the  limestone  in  the  quarries  at 
Reading,  but  I  omitted  to  notice  this  belt  of  overlying  slate,  which  Mr. 
d'Invilliers  has  no  doubt  of  being  No.  Ill,  and  not  primal  slates. 


358  GEOLOGICAL   SURVEY    OF   PENNSYLVANIA. 

lies  about  midway  between  the  Round  Top  and  Dividing 
Mountain  spurs.  The  limestone  of  No.  II  is  exposed  in 
this  valley  between  Doylesburg  on  the  IS".  E.  and  the  Rich- 
mond furnace  on  the  S.  W.  and  is  nowhere  over  two  miles 
wide,  tapering  toward  each  end.  The  north  dips  toward 
the  mountain  flank  are  usually  somewhat  steeper  than  those 
on  the  south  side  of  the  axis,  especially  for  a  distance  of 
six  or  eight  miles  in  Metal  township,  owing  largely  to  the 
presence  of  a  fault  along  the  base  of  the  mountain,  which 
swallows  up  a  large  portion  of  the  No.  Ill  slate  formation, 
and  opposite  Fannettville  brings  the  limestones  of  the  val- 
ley within  close  proximity  to  the  mountain  sand  rock  No. 
IV.  Along  this  line  the  dips  are  often  vertical,  if  not 
overturned  to  the  S.  E.  and  it  is  mainly  in  this  portion  of 
the  limestone  area,  near  the  junction  of  Nos.  II  and  III, 
that  the  iron  ores  of  this  region  are  exposed  and  developed 
for  a  distance  of  about  eight  miles  between  Richmond  fur- 
nace and  Fannettville.  The  South  Pennsylvania  branch 
of  the  Cumberland  Valley  railroad  was  originally  con- 
structed to  reach  these  deposits,  which  were  then  thought 
to  be  of  great  extent  and  purity,  but  which  after  a  consid- 
erable development,  have  proved  a  source  of  expensive  dis- 
appointment to  the  projectors  of  the  road  and  those  inter- 
ested in  the  resources  of  that  region.* 

Richmond  bog  ore  bank  at  the  S.  W.  end  of  the  range, 
3000'  N.  of  Bear  Knob  ;  long  abandoned,  20'x20'xlo'  deep  5 
uniformly  good  rich  non-phosphatic  ore,  but  not  much  of  it. 

Mount  Pleasant  bank,  the  oldest  and  largest  of  this 
range  ;  two  open  cuts  separated  by  barren  clay  partition  at 
S.  W.  end  and  uniting  in  one  large  open  cut  at  N.  E.  end 
towards  Cowan's  Gap.  Southern  cut  still  250'  x  100'  x  60' 
deep,  although  a  good  deal  filled  up  since  its  working  was 
abandoned.  A  60'  high  steep  barren  red-sand-wash  wall 
on  the  S.  E.  in  which  a  few  decomposed  layers  of  sandstone, 
with  steep  (overturned  ?)  S.  E.  dip,  appear  above  the  con- 
formably dipping  limonite.  On  the  N.  W.  side,  the  divid- 
ing partition  is  largely  of  white,  bine  and  yellow  clays. 

*DTnvilliers  in  Annual  Report  1886,  part  IV,  page  1490.  The  following 
description  of  the  banks  is  greatly  condensed  from  pages  1401  to  1501. 


PATH   VALLEY   MINES   IN   FRANKLIN   COUNTY.  359 

Behind  the  partition  dense  close-grained  limonite  under 
sooty-black  clay  ;  left  in  wall  a  N.  W,  dipping  lens-shaped 
bed  10'  to  20'  thick,  interrupted  by  barren  clays.  Total  length 
450'.  On  the  mountain  side  8'  to  20'  of  stripping  stopped 
work  in  that  direction.  Total  output  said  to  be  100.000 
tons.  Analyses:  Iron,  47.5;  manganese,  2.3;  sulp.,  0.05; 
phos.,  0.34 ;  silicions  matter,  11.7. 

Beaver  bank,  2500'  N.  E.  of  last;  200'  x  150'  x  20'  to  40' 
deep  ;  bed  of  limonite  20' thick  said  to  be  left  along  E.  wall. 
A  rib  of  barren  iron  stained  sandstone  extends  through 
the  middle  of  the  oval  open  cut ;  and  another  shows  in  the 
N.  W.  (mountain)  wall,  through  which  a  drift  reached 
some  good  ore.  No  black  clay  ;  all  the  barren  stuff  is  red. 
Whole  output  10,000  tons  ;  ore  very  irregularly  scattered  ; 
well  80'  deep  in  floor,  said  to  have  gone  through  good  wash 
ore. 

McGowan  pit,  1000'  N.  E.  of  last ;  small,  irregular ;  all 
wash  ore ;  no  black  clay  ;  less  red  than  white  and  yellow 
clay.  Worked  long  ago.  Other  small  pits,  abandoned  ; 
one  20'  deep  said  to  have  been  all  good  lump  ore.* 

Well  up  the  mountain  side,  N.  W.  of  the  banks  at  the 
foot  of  the  slope  just  described,  is  another  range  of  banks  : 

Old  Johnson  bank  ;  furnished  say  500  tons  of  ore  mixed 
through  a  sand  and  clay  wash. 

Lessig pits  ;  the  one  furthest  (N.  E.)  yielded  say  200  tons 
of  slaty  cold-short  ore.  From  the  other  pits,  10'  to  18' 
deep,  clean  good  limonite,  say  50  tons  in  all.  The  outcrop 
runs  straight  across  both  tracts  and  would  yield  some  ore 
here  and  there  if  opened. 

Car  rick1  furnace  has  a  run  of  1^  miles  on  the  outcrop 
further  N.  E.  First  pit  50'x'30'xlO/,  yielding  considera- 
ble good  ore ;  shaft  10'  deep  in  floor  stopped  in  ore.  Porous 
wash  ore  making  tough  iron  shows  in  the  bank  wall  under 
7'  stripping.  Two  other  pits  (600'  N.  E.  of  last),  50'x25'x 
15'.  gave  say  500  tons  of  ore  condemned  at  the  furnace. f 

*The  banks  described  above  are  on  S.  Pa.  M.  &  R.  R.  Co.'s  tract  of  6000 
acres.  The  company  holds  leases  on  several  thousand  acres  more ;  but 
the  field  is  practically  abandoned. 

f  This  is  a  curiously  interesting  illustration  of  the  variation  in  quality  in 
limonite  along  one  and  the  same  outcrop  line. 


360  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

After  many  smaller  pits  comes  a  large  one,  lOO'xSO'xSO':  a 
25'  shaft  in  the  floor  produced  excellent  lump  ore.  No 
water  here  ;  water  scarce  in  all  the  pits  ;  pits  therefore  often 
abandoned  even  when  good  ore  could  be  got.  Another  cut 
(a  little  lower  down  the  slope)  300'  N.  E.  of  last ;  150'x50'x 
20' ;  slope  (very  old)  put  down  20'  on  N.  W.  side  in  good 
lump  ore. 

Old  Carrick  bank,  %  m.  further  on  N.  E.  and  just  in  front 
of  the  Wind  Gap  by  which  the  road  passes  over  into  Hunt- 
ingdon county.  Here  only  the  top  of  No.  Ill  crops  out, 
all  the  rest  of  the  slate  formation  being  swallowed,  up  in 
the  fault  •*  and  the  ore  mine  300'x40'x25'  runs  along  the 
fault  and  close  to  the  limestone.  A  shaft  125'  deep  sunk  in 
the  mine  floor  is  said  to  have  passed  through  a  steeply  dip- 
ping 30'  to  35'  ore  bed.  Another  shaft  (at  W.  end)  is  said  to 
have  gone  75  feet  through  this  ore  and  stopped  in  solid 
lump-ore.  Yet  the  whole  place  is  abandoned  and  dilapi- 
dated. Most  of  the  output  came  from  gallery  workings  N. 
E.  and  S.  W.  of  the  ravine.  All  the  wall  towards  the 
mountain  shows  soft  sooty  black  clay,  like  that  which  caps 
so  manv  of  the  mines  along  the  foot  of  the  South  mount- 
ain. Four  sets  of  lessees  have  worked  the  mine  ;  output 
estimates  vary  so  as  to  be  worthless.  Analyses  of  samples 
of  ore  used  by  Carrick  furnace  in  1880:  (1)  lump  ore: — 
Iron,  45.3;  mang.,  1.1  ;  sulp.,  0.05;  sil.  mat.,  16.3  ;  phos., 
0.36— (2)  wash  ore  :— 36.4  ;  1.7  ;  0.06  ;  26.0  ;  0.27. 

Railroad  bank  (Carrick  Fur.  Co.)  1200'  further  N.  E. 
than  last ;  400/x40/xl6/;  not  much  ore  visible  in  1886;  strip- 
ping very  heavy;  shaf t 'under  S.  E.  wall  40'  (reported)  en- 
tirely in  ore,  and  in  drifts  to  N.  and  W.  Bank  must  have 
had  a  very  large  output.  Analysis  of  a  sample  picked 
up:— Iron,  43.6;  mang.,  0.24;  sulp.,  0.005;  sil.  m.,  18.5; 
phos.,  1.482  (unusally  large). 

A  few  more  pits  are  seen  further  on  N.  E.  beyond  the 
Fannettville  road  ;  outcrop  distinct  for  more  than  a  mile  ; 
G.  Umbril's  abandoned  pit  being  the  last. 

A  short  distance  E.  of  Mercersburg  are  three  small  banks, 

*Henderson's  fault,  as  we  used  to  call  it,  because  discovered  and  described 
by  A.  A.  Henderson  of  the  First  Geol.  Survey  of  the  State  1839-40. 


THE   IIENRIETA    MINES    OF   BLAIR   COUNTY.  361 

Leib's,  Stauffef '«?,  McFarland1  s,  now  abandoned,  which 
yielded  some  good  bog  ore. 


Stinger's  old  pits  at  the  mouth  of  Bear  valley,  1  m.  E.  of 
London,  and  on  or  near  the  II-III  line ;  long  abandoned  ; 
analysis:  Iron,  39.5;  mang.,4.8;  sulp.,  0.04;  sil.  m.,  18.8  ; 
phos.,  0.61. 

Garlic  Bank—E.  of  last  (2£  m.  S.  W.  of  St  Thomas) ; 
200'xlOO'x20';  walls  of  red  clay  carrying  fine  ore  and  a  little 
lump;  not  worked  for  15  years  (1886) ;  too  far  from  RR. ; 
good  ore;  analysis:  Iron,  52.9;  mang.,  0.08;  sulp.,  0.15; 
sil.  m.,  6.89  ;  phos.,  0.06. 

In  the  other  direction  2  m.  W.  from  Mercersburg,  the 
Webster  bank  is  on  a  II-III  contact  line ;  abandoned. 

The  Henrleitamines  of  Blair  Co. 

These  limonite  deposits  are  the  only  others  to  be  described 
in  this  chapter  as  appearing  to  have  a  geological  horizon  at 
the  top  of  II,  in  contact  with  the  slates  of  III,  and  along 
lines  of  fault  like  the  Path  Valley  mines  in  Franklin 
county  last  described.* 

Leather  cracker  Cove  is  made  by  an  anticlinal  of  No.  II 
limestone,  faulted  on  both  sides,  so  that  the  arch  is  thrown 
up  2000'  and  rests  against  the  slates  (III)  and  the  sand- 
stones (IV)  of  Tussey  mountain  to  the  east,  and  of  a  small 
slate  ridge  (III)  to  the  west.  The  big  fault  (the  eastern  one 
at  the  foot  of  Tussey)  is  about  a  mile  long,  and  approxi- 
mately parallel  with  the  strike  of  the  country.  The  anti- 
clinal runs  on  N.  20°  E.  to  and  through  Canoe  Valley  in 
Huntingdon  county.  See  Fig.  A  in  Report  T,  p.  91. 

*  I  am  loth  to  mix  these  up  with  the  great  mines  of  the  Great  Valley,  and 
to  separate  them  from  the  regional  mines  of  Nittany  Valley  and  Morrison's 
cove  ;  but  they  are  the  only  notable  mines  in  middle  Pennsylvania  behind 
the  Great  Valley  referable  to  the  top  of  II,  when  I  made  my  last 
survey  of  that  iron  region  ;  all  the  other  limonite  deposits  of  II  being  re- 
ferable to  various  horizons  in  the  body  of  the  formation.  But  it  will  ap- 
pear in  a  subsequent  chapter  (XXXIV)  that  I  now  place  a  different  inter- 
pretation on  that  fact,  and  believe  that  the  Henrietta  ore  horizon  is  only  ac- 
cidentally connected  with  the  slates  of  III  by  reason  of  a  great  upthrow 
fault 


362  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 


lALap  cft/te  SaticonZinc  TTtlnes  cuici  vicinity.  ~Pl.  XII  . 


THE   HENRIETTA   MINES   OF   BLAIR   COUNTY.  363 

The  line  of  contact  limonite  ore  deposits  runs  from  the 
Henrietta  bank  due  south.  At  the  south  end  of  the  line 
of  ore  the  Oneida  terrace  (IVa)  and  the  Hudson  river 
slates  (UK)  are  swallowed  by  the  fault.*  It  seems  a  logi- 
cal conclusion  that  this  line  of  limonite  ore  has  been  pro- 
duced in  some  way  by  the  fault.  The  contact  of  II  and  III 
is  sharply  defined  along  Tussey  mountain  its  whole  length 
across  four  counties,  and  along  Dunnings,  Lock,  Loop, 
Canoe,  Bald  Eagle  and  Nittany  mountains,  for  about  a  hun- 
dred miles  of  outcrop.  Almost  every  ravine  cutting 
through  the  terrace  of  slate  into  the  limestone  valley  affords 
as  good  an  opportunity  as  could  be  desired  for  finding  any 
ore  deposits  existing  at  the  contact  of  the  two  formations, 
or  produced  by  the  decomposition  of  lime-shale  beds  of  pas- 
sage from  limestone  to  slate.  In  most  cases  the  cultivated 
fields  at  the  base  of  the  mountain  would  betray  the  pres- 
ence of  such  ore  deposits.  In  spite  of  all  this  however  not 
a  single  such  discovery  of  any  importance  has  been  reported, 
except  in  Leathercracker  cove.  The  conclusion  is  obviously 
good  that  the  Henrietta  ore  mines  occupy  this  geological 
horizon  exceptionally,  by  accident,  and  solely  in  virtue  of 
the  Leathercracker  faults. 

But  this  conclusion  has  a  wider  range  and  applies  forc- 
ably  to  the  Great  Valley,  where  we  see  the  Path  Valley 
deposits  of  Franklin  county  lying  along  just  such  another 
fault ;  and  then  we  must  go  140  miles  along  the  middle  con- 
tact line  II  and  III  before  we  reach  the  Moselem  mine  in 
Berks  county,  where  we  have  seen  there  is  some  reason  for 
suspecting  a  faulted  structure.  In  the  Ironton  region  of 
Lehigh  county  there  is  scarcely  a  single  mine  which  can  be 
assigned  with  certainty  to  the  contact  of  II  and  III ;  and 
from  Ironton  eastward  no  deposits  of  limonite  can  be 
proved  to  overlie  the  Trenton.  Even  at  Cornwall  there  is 
solid  limestone  (Trenton  ? )  at  the  very  top  of  the  ore  shale 
mass.  Remembering  that  no  limonite  appears  with  the 
passage  beds  in  the  bends  of  the  Conedogwinit  in  Cumber- 
land county,  and  keeping  always  in  mind  that  we  have  as 

*A11  the  arguments  for  the  fault  are  given  successively  in  detail  in  T, 
p.  90,  to  which  the  reader  is  referred. 


364  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

yet  no  assistance  from  fossil  forms  in  determining  the  true 
position  of  any  limestone  or  lime  shale  beds  faulted  against 
the  slates  of  III  at  Henrietta  mine  or  elsewhere,  it  must  be 
regarded  as  quite  possible  that  all  our  Great  Valley  limo- 
nites  are  cavern  deposits  of  very  recent  date  derived  from 
the  decomposition  of  a  series  of  damourite  lime  shales  be- 
longing to  various  horizons  in  the  Magnesian  limestone  for- 
mation, that  is,  the  Chazy  and  Calciferous. 
In  the  next  chapter  such  horizor^s  will  be  exhibited. 


NITTANY   VALLEY   LIMESTONES   NO.    II.  365 


CHAPTER  XXXI. 

Nittany  Valley  limestones,  No.  II.     Centre  County  anti- 
clinals.     Nittany  Valley  cross -sections. 

The  ore  horizons  of  the  Great  Valley  have  been  seen  to 
be  obscured  by  the  folded  and  crumpled  condition  of  lime 
stone  and  slate  belts.  In  Nittany,  Brush,  Penns,  Canoe 
and  Kishicoquillis  valleys,  and  in  Morrison's,  Friend's  and 
McConnellsburgh  coves,  a  simple  anticlinal  structure,  dis- 
turbed by  only  a  few  faults  and  hardly  at  all  crumpled, 
makes  the  order  of  the  limestone  beds  an  easier  study, 
sufficient  to  establish  the  different  horizons  by  approxi- 
mately parallel  ranges  of  ore  banks.* 

The  great  rock  waves  of  Middle  Pennsylvania  are  splen- 
didly exhibited  in  the  McConnellsburgh  Cove  in  Fulton 
county,  with  its  8000'  fault  on  the  western  side  ;  in  Kishi- 
coquillis valley  in  Mifflin  county,  with  its  surrounding  ter- 
race and  eastern  keel-shaped  mountain  prongs  ;  and  most 
of  all  in  Nittany  valley  and  Morrison's  Cove  (united  by 
Canoe  valley)  where  the  grandest  anticlinal  of  the  State 
brings  to  the  surface  the  whole  of  the  magnesian  limestone 
(capped  by  400'  of  Trenton  limestone)  with  immense  de- 
posits of  iron  ore.  A  description  of  the  Nittany  anticlinal, 
and  of  the  subordinate  waves  which  broaden  and  spread  out 
its  southern  slope,  is  a  necessary  preliminary  to  the  descrip- 
tion of  that  oldest  and  richest  iron  ore  region  of  middle 
Pennsylvania. 

Centre  county  anticlinals. 

The  great  Nittany  valley  anticlinal,  which  brings  to  the 
surface  the  top  layers  of  No.  II  in  Mosquito  valley  in 

*Mr.  D'Invilliers  in  Report  T4,  p.  137-8,  says  that  the  popular  belief  in 
continuous  belts  of  ore-producing  territory  along  fixed  outcrop  belts  or 
horizons  was  not  confirmed  by  his  survey  of  Centre  county  ;  but  this  does 
not  invalidate  the  statement  that  limestone  horizons  are  demonstrable,  and 
ore  horizons  approximately  so. 


366  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 


Ft.  XIII. 

&WM  Section*  tfJfoJl  in  Jfittaivy  Valley,  GemtivGo. 


Chestnut  ndge    taledwy'rirfye-.. 


zfetD 


CENTRE   COUNTY    ANTICLINALS.  367 

Lycoming,  and  Nippenose  valley  in  Clinton,  rises  in  Cen- 
tre county  so  as  to  expose  on  the  Centre-Huntingdon  line, 
west  of  Bellefonte,  at  least  6000'  of  the  formation,  without 
however  bringing  the  bottom  beds  to  the  surface.* 

Continuing  S.  W.  across  Huntingdon  into  Blair  at  a  still 
higher  elevation  it  exposes  more  than  6000'  of  No.  II  down 
to  (or  nearly  to)  the  bottom  beds  at  Birmingham  on  the 
Little  Juniata.  Then  it  sinks  rapidly  to  the  head  of  Sink- 
ing Creek  valley,  where  the  slates  of  III  close  over  it,  and 
the  mountain  rocks  of  IV,  the  Frankstown  fossil  ore  red- 
shales  of  V,  and  the  Hollidaysburg  limestones,  etc.  cover 
it;  and  so  it  runs  on  south  through  the  Devonians  into  the 
coal  measures  of  Somerset  county. 

The  Gatesburg  ridge  anticlinal  in  Centre  county  runs 
parallel  and  1J  miles  to  the  S.  E.  of  the  Nittany  (Chestnut 
ridge)  anticlinal  ;  and  becomes  the  Hickory  ridge  anti- 
clinal of  Huntingdon  county,  crossing  Half  Moon  creek  2 
m.  N.  of  its  junction  with  Spruce  creek. f 

Dry  Hollow  synclinal  lies  between  the  Chestnut  ridge 
and  Hickory  ridge  anticlinals. 

Sand  ridge  (Tadpole  ridge}  anticlinal  in  Centre  county, 
runs  parallel  and  1£  m.  S.  E.  of  the  Gatesburg  ridge  anti- 
clinal, and  its  S.  E.  dips  pass  beneath  Spruce  creek  down 
into  the  roots  of  Tussey  mountain.  It  is  the  Spruce 
creek  anticlinal  of  Huntingdon  county.  On  the  county 
line,  opposite  Pennsylvania  furnace,  it  brings  to  the  surface 

*  D'Invilliers  in  T3,  p.  443 :  East  of  Bellefoute  the  axis  beds  are  the  "  Bar- 
ren "  sandrocks  of  Sand  ridge ;  west  of  Bellefonte  the  axis  runs  along  Chest- 
nut ridge.  Its  S.  E.  dips  are  rather  gentle  here,  but  its  N.  W.  dips  (in  the 
Stormstown  valley,  1^  miles  wide,  between  Chestnut  ridge  and  Bald  Eagle 
mountain)  are  steep,  vertical,  or  even  overturned  so  as  to  dip  S.  E. 

f  This  arch  is  quite  subordinate  to  the  great  Nittany  arch,  and  is  in  fact 
a  roll  on  the  grand  S.  E.  slope  of  the  formation  from  the  Nittany  arch  crest 
towards  Tussey  mountain.  One  result  is  that  the  Hickory  ridge  barrens 
are  not  the  Sand  ridge  barrens  of  Centre  county,  but  are  much  higher  in 
the  series  ;  giving  us  two  quite  distinct  horizons  of  Calciferous  sandstone 
strata  in  No.  II.  This  roll  appears  to  die  down  rapidly  N.  E.  and  S.  W. 
from  Half  Moon  run,  and  probably  flattens  out  before  reaching  Warrior 
run  ;  at  all  events  there  is  no  trace  of  it  in  the  long  exposures  of  the  Little 
Juniata.  It  seems  to  bring  up  the  particular  horizon  of  shales  from  which 
the  Old  Seat,  Huntingdon  furnace,  and  Dorsey  ore  deposits  were  generated. 
(D'Invilliers  letter  of  May  18,  1885,  in  T3,  p.  445.) 


368  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

3500'  of  No.  II ;  and  it  is  in  this  upper  half  of  the  for- 
mation that  most  of  the  pipe  ores  of  the  region  are  mined.* 

The  Brush  valley  anticlinal  runs  along  at  the  S.  E.  foot 
of  Nittany  Mountain,  between  it  and  Brush  mountain. f  It 
passes  north  of  Rebersburg  and  Madison ville,  with  N.  W. 
dips  of  65°  to  70°,  and  S.  E.  dips  of  15°  to  20°.  Just  north 
of  the  Penns  Valley  cave,  pure  soft  gray  Trenton  limestone 
beds  dip  70°  N.  W.  and  45°  S.  E.  It  reaches  its  greatest 
height  near  Centre  Hall,  where  it  brings  to  the  surface  beds 
2500'  beneath  No.  TIL:}:  Sinking  and  flattening  S.  W.  it  car- 
ries the  Watson,  Ross,  Stover  and  other  ore  deposits.  On 
Spring  creek.  1£  m.  S.  of  Lemont,  its  dips  are  48°  N.  W. 
and  12°  S.  E.,  flattening  to  8°  at  Boalsburg.  Then  it  rap- 
idly dies  out  before  reaching  the  foot  of  Tussey  mountain. 

The  Penns  Valley  anticlinal  runs  south  of  Brush  mount- 
ain, between  it  and  Stone  mountain,  in  the  slates  of  III  in 
Pine  Creek  Hollow  ;  lifts  the  top  Trenton  beds  at  Hoster- 
man's  saw  mill,  and  rims  into  a  cove  of  Tussey  mountain. § 

TJie  Penns  Narrows  anticlinal  barely  lifts  to  the  surface 
in  the  Narrows  and  in  George's  valley  the  top  Trenton 

*This  Sand  ridge  anticlinal  axis  runs  from  Pennsylvania  furnace  (N.  E.) 
to  Johnston's  ore  bank  in  College  township,  lapping  past  the  dying  Brush 
Valley  anticlinal ;  and  between  the  two  begins  the  Nittany  mountain  syn- 
clinal which  deepens  (N.  E.)  and  takes  in  the  slates  of  III,  the  sandstone 
of  IV,  and  the  red  shale  of  V,  which  make  the  canoe-shaped  Nittany  mount- 
ain. At  Pennsylvania  furnace  the  Sand  Ridge  dips  vary  from  25°  to  60°, 
N.  W.  and  25°  to  40°  S.  E.  At  Johnston's  bank  its  S.  E.  dips  vary  from 
15°  to  30°.  (T4,  35.) 

f  Eastward  this  axis  makes  Sand  mountain  in  Union  county  and  crosses 
the  Susquehanna  near  New  Columbia.  Westward  it  curves  from  W.  toS.  W. 
just  as  the  Nittany  valley  anticlinal  does,  entering  Centre  county  in  Miles 
township  at  the  head  of  the  narrow  Hudson  river  slate  cove  with  which 
Brush  valley  commences.  It  brings  up  the  top  Trenton  beds  near  Rudy's 
mill. 

JThis  accounts  for  the  ore-poverty  of  Brush  valley;  the  uppermost  ore 
horizons  on  steep  dips  affording  no  good  opportunity  for  concentration  and 
preservation  ;  and  the  rest  being  buried. 

§  It  crosses  the  Susquehanna  north  of  Lewisburg.  On  e  mile  east  of  Aaron  s- 
burg  its  limesand  beds  dip  68°  N.  25°  W.  and  40<-'  S.  35°  E.  It  bends 
sharply  southwards  and  crosses  the  pike  i  m.  S.  of  Millheim,  where  dips  of 
70°,  640,  go0  N.  W.,  and  12°,  20°,  30°  S.  E.  are  seen.  Then  it  bends  and  runs 
due  west  to  the  church,  1  m.  N.  E.  of  Penn  Hall ;  here|m.  N.  of  edge  of  III 
in  Egg  Hill.  North  of  Spring  Mills  its  dips  are  60°  N.  W.,  20°  S.  E,  Gentle 
arch  at  Penns  creek  ;  greatest  height  2m.  further  west  on  the  Bellefonte- 
Lewistown  pike  ;  then  turns  S.  W.  and  dies  into  the  Tussey  mountain  cove. 


CROSS   SECTIONS   IN    CENTRE   COUNTY.  369 

beds,  with  dips  of  70°  N.  W.  and  60°  S.  E.  Its  highest 
point  is  2  m.  W.  of  the  MiJlheim  pike  with  dips  of  70°  N. 
W.  and  50°  S.  E.  At  Potter's  mills  are  dips  of  85°  N.  W. 
and  70°  to  80°  S.  E.  It  sinks  west  in  the  slate  "Loop"  4 
m.  west  of  Potter's  mills,  and  issues  S.  W.  from  Tussey 
mountain  at  the  Bear  Meadows  in  Huntingdon  county.* 

It  will  be  seen  from  the  above  sketch  of  the  structure 
and  from  the  figured  cross-sections  why  almost  all  the  limo- 
nite  ore  deposits  are  confined  to  the  Nittany  valley  proper, 
the  great  arch  of  which  brings  up  nearly  the  whole  of  for- 
mation No.  II,  exposing  to  erosion  and  concentration  all 
its  iron-bearing  limeshale  and  limesand  horizons. 

Cross-sections  in  Centre  Co. 

Figs.  1,  2,  3,  4,  5,  6,  on  Plate  XIII  show  the  structure  of 
the  region  by  a  series  of  cross  sections  described  in  Mr. 
D'lnvilliers'  report  on  Centre  county,  T4,  1884,  pp.  34 
to  41.  The  rest  appear  as  plates  p.  668  &c.  below. 

The  Madisonburg  Gap  cross-section,  at  the  Clinton- 
Centre  county  line,  shows  the  Nittany  axis  barely  a  mile 
distant  from  the  Bald  Eagle  mountain  in  which  the  slates 
of  III  are  vertical  or  overturned  (S.  E.  80°  to  86°).  Against 
these  rest  the  thin-bedded  shaly  Trenton  limestones  (He) ; 
against  these  rest  the  white,  hard  crystalline,  magnesian, 
sandy  Chazy  limestones  ;  and  under  these  on  the  arch  the 
limy  sandstones  of  Sand  ridge,  making  "The  Barrens." 
At  the  Washington  Furnace  and.  Beck  ore  banks  (2£  m.  N. 
W.  of  the  old  Washington  furnace)  the  measures  are  over- 
turned, and  the  ore  horizon  is  about  3000'  beneath  the  Slates 
of  III.  South  of  the  arch  the  same  ores  lie  at  the  Snavely, 
Sallow  and  Day,  and  Huston  banks,  dipping  30°,  S.  85° 
E.  (towards  Nittany  mountain)  between  beds  of  cherty  lime- 
stone (Chazy,  or  Calciferous) ;  the  slates  of  III  at  the  base 
of  the  mountain  dipping  40°,  and  the  Medina  sandstone 
50°,  S.  E. 

*  The  Confer  anticlinal  only  exposes  III  in  Decker  valley,  and  in  the 
small  oval  Lick  valley  (Lechenthal). 

The  Poe  Valley  anticlinal,  passing  from  Union  into  Mifflin  county,  also 
only  exposes  III  along  the  north  foot  of  Paddy's  mountain  and  south  foot 
of  Bald  mountain. 

24 


370  GEOLOGICAL    SURVEY   OF   PENNSYLVANIA. 

The  Howard  and  Jacksonville  cross-section,  4  m.  S.  W. 
of  the  last,  shows  the  sand-lime  strata  (containing  some 
good  pale  blue  beds)  at  Jacksonville  overturned  68°  to  80°, 
S.  E.  without  any  appearance  of  a  break  or  fault  in  the 
arch.  Fossiliferous  blue  limestone  quarries  are  N.  W.  of 
the  village  ;  and  black  shiny  Utica  slate,  polished  by  slid- 
ing pressure,  within  300'  of  the  Bald  Eagle  mountain,  has 
been  prospected  for  coal !  Near  the  Butler  ore  bank  inter- 
stratified  magnesian  limestone  and  common  sandstone 
beds  are  overthrown  to  50°  or  60°,  S.  E.  Sand  ridge  has  a 
double,  crest,  the  northern  crest  being  made  by  very  hard 
blue  flaggy  sandstone  beds;  the  southern  covered  with 
loose  sand.  The  sandstone  beds  are  regularly  inter  strati- 
fied with  the  magnesian  limestone  beds.  The  higher 
southern  ridge  shows  20°  to  25°  dips  to  S.  E.  The  ore  hori- 
zon in  Madison  Gap  cross- section  above  here  runs  through 
the  Hecla,  Voneda,  and  Schwartz  mine  limestones  dipping 
30°  to  40°,  S.  E.  Then  come  the  overlying  dark  blue  Trenton 
beds  (He)  making  a  reddish  soil ;  then  the  Utica  black 
slates,  extensively  prospected  for  coal,  on  the  H.  Brown 
tract,  dipping  40°,  S.  E. 

The  Hecla  Furnace  cross- section,  3m.  W.  of  last.  In 
Little  Fishing  Creek  Gap  IV  dips  52°,  40°,  40°,  S.  E.  Be- 
tween Nittany  mountain  and  Sand  ridge  a  shallow  valley. 
Blue  very  slightly  calcareous  sandstones,  dipping  22°,  S.  E. 
were  once  quarried  for  paving  flagstones  (40°,  S.  30°  E.) 
near  the  McKinney  ore  bank.  At  the  Darrah  bank,  N.  W. 
of  the  Sand  ridge,  the  same  blue  silicious  magnesian  lime- 
stones in  bold  ledges  and  cliffs  dip  20°  to  25°,  8.  E.  into  the 
ridge.*  Along  the  north  road,  magnesian  limestones  are 
overturned  to  85°,  83°,  70°,  83°,  80°,  88°  to  S.  E.,  but  others 
dip  85°,  88°,  60°,  65°,  76°  normally  N.  W.  The  anticlinal 
begins  to  get  its  normal  shape  after  passing  S.  W.  into 
Spring  township. 

The  Belief onte  cross-section  is  the  best  that  can  be  got 
N.  E.  of  the  Little  Juniata.  The  Barrens  (sand  ridge), 
sinking  4m.  E.  of  Belief  onte,  do  not  show  the  sandstones 

*This  is  a  mile  from  Bald  Eagle  mountain  and  must  mean  an  excessive 
overturn. 


CROSS   SECTIONS   IN   CENTRE   COUNTY.  371 

on  the  section.  The  Medina  sandstones,  IV,  in  Bald  Eagle 
mountain  dip  80°  to  70°,  N.  W.  The  slates  of  III  on  the 
mountain  side,  50°,  N.  W.  The  Trenton  blue  fossiliferous 
limestones,  IIIc,  600'  thick,  both  massive  and  thin  bedded, 
fine  grained  and  laminated,  dip  50°,  N.  W.,  as  in  the  Alex- 
ander and  Morris  quarries  on  Spring  creek  north  of  Belle- 
fonte.  Then  at  the  Presbyterian  church  appear  the  upper- 
most magnesian  (Chazy)  beds,  banded,  broken  by  cleavage 
holding  masses  of  chert,  and  decidedly  whiter  than  those 
above  them ;  all  of  them  more  or  less  sandy  and  cross- 
cracked  ;  dipping  on  an  average  50°  (with  local  variations 
of  30°  to  60°)  N.  W.  to  the  anticlinal  axis,  a  mile  S.  of 
Bellefonte,  were  they  only  dip  9°  N.  W.  and  S.  E.  Then 
the  same  beds  descend  in  the  same  order,  with  S.  E.  dips  of 
30°,  20°,  12°  and  10°,  toward  Nittany  mountain. 

The  Fillmore-Boalsburg  cross-section,  6  miles  further  S. 
W.  crosses  the  whole  valley  (£  m.  W.  of  the  end  of  Nit- 
tany mountain)  from  the  Bald  Eagle  mountain  to  Tussey 
mountain,  8  miles,  across  the  Nittany  valley  anticlinal,  the 
Nittany  mountain  synclinal,  and  the  Brush  Valley  anticli- 
nal. Here  the  bottom  slates  of  III  dip.  70°,  N.  W.  The 
blue  Trenton  beds,  at  first  70°,  lower  their  dips  so  rapidly 
that  at  Fillmore  they  dip  only  20°  to  15°,  N.  W.  Half  a  mile 
further,  on  Crust  farm,  the  arch  of  lime-sandstones  is  flat- 
tened to  6°  dips  both  ways  (10°,  12°,  well  exposed  on  Spring 
Creek,  1  m.  S.  of  Roopsburg).  South  of  the  axis  in  Big 
Hollow,  N.  W.  of  Houserville,  purer  limestones  descend  at 
10°,  15°,  18°,  16°,  30°,  S.  E.  into  Paddington  ore  banks.  On 
Slab  Cabin  run,  15°,  20*,  S.  60°  E.  (showing  the  shoaling  of 
the  Nittany  mountain  synclinal).  Here  the  long  syncli- 
nal prong  of  III  is  crossed.  Then  the  Trenton  limestones 
rise  steeply  (50°,  60°,  N.  20°  W.).  Then  the  lime  sandstones 
rise  (48°,  N.  W.)  on  the  Brush  Valley  anticlinal,  and  sink 
again  (8°  to  12°,  S.  E.  )covered  by  the  Trenton  beds  descend- 
ing at  20°  to  30°  under  the  slates  of  III  in  Tussey  mountain. 


372  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

CHAPTER  XXXII. 

Centre  county  limonite  mines.     Pennsylvania  Furnace 
ore  banks. 

Mr.  E.  V.  d' Invilliers'  elaborate  report  on  Centre  county, 
T4,  was  published  in  1884,  when  the  iron  industry  of  the 
state  was  depressed,  when  only  three  of  the  four  small  char 
coal  furnaces  were  in  blast  and  the  supply  of  water  for 
washing  the  limonite  ores  of  the  county  was  very  limited. 

Since  that  date  there  has  been  an  active  movement  in  de- 
veloping the  iron  ore  resources  of  the  district.  Two  large 
coke  furnaces,  with  the  latest  improvements,  have  been 
erected  at  Belief  on  te  by  the  Robert  Valentine  Company,  and 
the  Philip  Collins  Company,  and  operated  under  various 
changes  of  name.  Brown  hematite  banks  have  been  opened 
up  all  along  the  ore  belts,  especially  in  the  middle  mem- 
bers of  the  limestone  series.  Branch  railroads  have  been 
constructed  to  reach  the  mines  near  the  State  College  and 
along  the  foot  of  Bald  Eagle  mountain.  The  use  of  jigs  to 
separate  the  ore  from  the  Hint  and  sandstone  of  the  ore 
masses  is  now  common  and  will  soon  be  universal.  Water 
for  washing  away  the  clay  and  sand  is  procured  either  from 
the  surface  streams  or,  in  the  dry  limestone  districts,  by 
sinking  artesian  wells  to  the  drainage  level ;  some  of  them 
being  several  hundred  feet  deep,  and  at  least  one  of  them 
west  of  the  Huntingdon  county  line,  a  thousand  feet. 
The  market  for  the  ores  is  found  at  the  numerous  furnaces 
along  the  main  line  of  the  Pennsylvania  railroad  and  its 
branches.  The  fuel  used  is  coke  from  the  Clear-field  and 
Connellsville  coal  districts. 

Two  varieties  of  ore.  * 

The  two  chief  varieties  of  ore  occurring  in  the  county  are  : 
1st.  The  wash  and  lump  hematite  ore  of  the  "  barrens."  2d. 
The  pipe  ores. 

*This  paragraph  and  those  that  succeed  it  as  far  as  to  the  end  of  the  list  of 
mine  groups  are  taken  nearly  verbatim  from  Mr.  d'Invilliers'  report  on  Cen- 
tre county,  T4,  1884,  pp.  133  to  138.  His  detailed  descriptions  of  the  mines 
of  these  groups  occupy  117  pages  of  that  volume  (pp.  139  to  256)  of  which  no 
summary  can  be  made  with  any  success.  I  will  confine  myself  to  a  de- 
scription of  the  great  Pennsylvania  furnace  mine  and  refer  the  reader  for 
the  rest  to  his  excellent  work. 


CENTRE   COUNTY   LIMONITE   MINES.  373 

1.  Of  the  first  class  it  may  be  stated  that  the  appearance 
and  character  of  the  ore  in  all  the  banks,  as  well  as  the  ac- 
companying waste  material,  show  evidence  of  their  being 
waste  deposits,  caught  in  vast  caverns  of  irregular  shape, 
showing  mixed  sand,  tough  clay  and  rolled  ore,  and  though 
intimately  associated  with  sandy  measures  in  the  limestone 
formation  of  II  have  really  a  still  lower  limestone  bottom. 

In  the  chief  mines  of  the  district — notably  at  Scotia  and 
Tow  hill — after  a  superficial  covering  of  15  to  30  feet  of 
mixed  clay,  sand  and  fine  ore  has  been  removed,  the  under 
surface  reveals  solid  rock-ore  in  large  lumps,  mixed  with 
clay  in  a  confused  arrangement,  of  great  richness  and  va- 
riety. An  integral  difference  in  the  clays  of  these  ores  and 
the  limestone  pipe  ores  (one  to  be  expected  probably  from 
their  different  horizons)  is  the  much  greater  stiffness  and 
toughness  of  the  former.  The  clay  of  these  lower  ores  fre- 
quently occurs  in  non-ferruginous  bands  or  dykes,  running 
through  the  length  of  the  banks,  barren,  and  hard  .to  pass 
through  the  washers,  but  by  no  means  cutting  off  the  ore. 
This  non-ferruginous  clay  has  usually  a  white  to  pink 
color  ;  while  the  yellow  clay  of  the  pipe  ore  deposits  is  inti- 
mately mixed  with  the  ores  and  offers  no  material  resistence 
to  their  thorough  cleansing  in  the  washing-machines. 

Moreover,  it  may  be  noted  that  in  every  case  the  ore  of 
the  barren  needs  jigging  in  addition  to  washing  to  free  it 
from  the  mixed  sand  and  flint  that  accompany  it. 

All  the  analyses  of  these  ores  show  an  absence  of  bisul- 
phide of  iron,  and  the  occurrence  of  all  the  iron  as  sesqui- 
oxide  at  once  suggested  a  different  chain  of  effects  in  the 
production  of  these  as  compared  with  the  pipe  ores,  to  be 
presently  described,  where  this  salt  of  iron  is  frequently 
present. 

The  sand  rocks  which  originally  held  these  ores  occupy 
a  position  low  down  in  the  sandlime  series  of  II.  By 
having  their  lime  leached  out,  these  loosely  aggregated 
sandstones  have  fallen  into  sand,  and  it  is  probable  that 
this  same  leaching  action  has  concentrated  their  iron  salts, 
which  would  be  deposited  as  insoluble  peroxide.  What 
changes  may  have  followed  this  process  of  deposition  to 


374  GEOLOGICAL   SURVEY    OF   PENNSYLVANIA. 

bring  about  the  irregular  and  confused  appearance  of  the 
banks  to-day  and  the  grading  of  the  ore  body  from  fine  to 
coarse  lumps  is  a  matter  of  speculation  still.  The  deposits 
do  not  look  like  formations  in  situ,  nor  would  such  a  theory 
explain  the  rounded  character  of  ore  and  flint  balls  and 
occurrence  of  barren  spots  beside  nests  of  great  richness. 

While  no  distinctively  pipe  ores  have  been  reported  from 
the  ore  banks  in  the  "barrens,"  some  persons  detect  in  the 
compact  needle  ore  (occasionally  met  with)  a  form  of  pipe, 
and  illustrate  their  opinions  of  the  common  origin  of  pipe 
and  hematite  ores  by  this  fact.  Physically  and  chemically 
they  appear  to  be  quite  different ;  but  the  general  resem- 
blance of  all  ores  from  different  banks,  divided  only  as  to 
two  classes,  is  not  as  remarkable  as  the  local  variations 
which  give  rise  to  the  occurrence  of  bessemer,  neutral  and 
cold-short  ores  lying  quite  close  to  each  other,  and  appar- 
ently along  the  same  range. 

2.  The  pipe  ores  have  varying  horizons  in  the  limestone, 
and  though  generally  above  the  essential  ''barrens"  limo- 
nites,  it  is  by  no  means  certain  that  some  of  them  do  not 
occur  also  in  the  1000±  feet  of  limestone  beneath  these. 

The  frequent  connection  of  damourite  slate  beds  with  the 
chief  ore  bodies  in  the  southeastern  district  of  the  State  is 
not  observed  in  Centre  county.  It  is  true  that  most  of  the 
pipe  ores  are  accompanied  with  a  white  and  buff-colored  clay, 
which  may  be  the  result  of  the  decomposition  of  such  slate 
bands  ;  but  it  may  also  represent  the  disintegration  of  the 
magnesian  limestones  themselves. 

While  the  chemical  explanation  of  these  facts  is  still  a 
matter  of  speculation,  repeated  examinations  of  the  ore 
banks  in  various  parts  of  Nittany  and  Penns  valleys  leads 
me  to  believe  that  the  pipe  ores  are  deposits  probably  due 
either,  first:  To  the  decomposition  of  iron  pyrites,  origi- 
nally contained  in  the  limestone  or  slate  bands,  and  after 
oxidation  as  sulphate,  filled  into  interstices  in  the  limestone, 
and  changed  into  peroxide  by  contact  with  vegetable  mat- 
ter or  other  organic  substances  ;  or,  second  :  To  the  prior  pro- 
duction of  ferrous  carbonate,  by  reaction  between  the  fer- 
rous sulphate  and  the  calcium  carbonate  of  the  limestone, 


CENTRE   COUNTY   LIMONITE   MINES.  375 

afterwards  converted  into  limonite  by  oxidation  and  hydra- 
tion.  The  manner  of  occurrence  between  walls  of  regularly- 
bedded  limestone,  sometimes  as  thin  shells  of  ore  and  again 
as  large  pipes  in  masses  8  to  10  feet  thick,  would  confirm 
one  or  the  other  of  these  views,  while  the  presence  of  iron 
pyrites  in  perfectly  undecomposed  pipes  surrounded  with 
thoroughly  oxidized  ore  in  the  Sinking  Creek  mine  in  Penns 
valley,  lends  probability  to  the  theory.  The  presence  of 
pyrites  in  hematite  is  not  new,  and  the  many  analyses  show- 
ing bi-sulphide  of  iron  in  the  succeeding  pages  will  illus- 
trate its  frequency  in  this  district.  Crystallized  brown 
hematite,  a  pseudomorph  after  pyrite,  has  been  gathered 
in  the  Cumberland  valley,  as  well  as  specimens  of  bombr 
shell  ore  holding  a  clay  inside  filled  with  loose  crystals 
of  pyrites. 

In  other  banks  showing  a  low  percentage  of  sulphur 
many  of  these  ores  may  have  occurred  as  carbonates  in  the 
slates,  which  upon  the  dissolution  of  their  lime  matter 
have  deposited  these  iron  salts  as  now  found.  In  those 
banks  where  a  considerable  surface  deposit  has  escaped 
from  the  general  erosion,  this  oxidation  has  been  so  com*- 
plete  as  to  show  but  a  low  percentage  of  sulphur  ;  whereas, 
in  the  case  of  the  Sinking  Creek  mine  before  mentioned, 
the  ore  occurs  in  places  between  limestone  beds,  and  has  not 
yet  had  a  chance  to  become  thoroughly  changed. 

The  outcropping  of  these  pipe  ores  is  spread  out  to  a 
much  greater  extent  than  they  occupy  lower  down  be- 
tween limestone  layers.  The  width  of  these  outcrops  is 
affected  by  the  topography  of  the  country.  This  surface 
ore  is  greatly  disintegrated,  and  occasionally  is  indeed  so 
fine  as  to  be  hardly  distinguished  from  so  much  reddish 
brown  loam  or  earth  ;  but  a  close  inspection  of  it  will  re- 
veal the  presence  of  small  stems  or  pipes,  making  usually 
a  cubic  yard  of  ore  for  each  4  or  5  cubic  yards  of  material, 
and  often  better. 

The  work  of  the  season  did  not  confirm  the  popular  be- 
lief in  continuous  belts  of  ore-producing  territory  along 
miles  of  surface  outcrop.  At  best,  while  assigning  approx- 
imate horizons  to  these  pipe  ore  deposits,  they  have  their 


376  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 


Section  ofPenn's  Valley  through  BoaLsburg. 


/.  XIV. 


Section  through  the  Henderson  farm  S.W.ofBoalsburcj. 

*    , 


Map  ffftfie  <Pe7JiiAylrania  andaderlimoitifc  /a/net;,,  Centre  Co: 


CENTRE   COUNTY    LIMONITE   MINES. 


377 


JVate  XV. 

ci  limonite  mine  in  6enf/re  Go.  &CL. 


378  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

rich  and  poor  places — feather  out  entirely  in  the  line  of 
strike  and  widen  again  into  masses  several  yards  thick, 
while  keeping  a  general  parallelism  of  bedding  with  the 
parent  rock  and  liable  to  show  its  change  of  dip.  It  is  use- 
less to  speculate  on  the  possibilities  of  these  deposits,  but 
the  ore  has  been  found  at  great  depths,  and  much  original 
outcrop  soil  is  as  yet  untouched.  For  convenience  sake  it 
has  been  thought  best  to  describe  them  in  groups  geogra- 
phical rather  than  geological,  as  follows  : 

Belief onle-Nitlany  Valley  group,  embracing  the  follow- 
ing banks  :  Curtm  Bros.,  Fishing  Creek  bank,  Jackson 
mine,  Red  bank,  Hoy  bank,  etc.,  Gatesburg,  Taylor,  Nigh, 
and  Logan  banks. 

Jacksonville  Valley  group,  containing  Zimmerman, 
Darrah,  McCalmont,  Butler,  Beck  and  Washington  Fur- 
nace bank,  etc. 

Hublersburg  Valley  group,  with  the  Field,  McKinney 
•Quinn,  Hecla,  Howard,  Voneda,  Schwartz,  Huston  1  and  2, 
Snavely  and  Barlow  &  Day  mines. 

Buffalo  Run  group,  Hunter,  Crust,  Markle,  Lambourn, 
Pond,  Newell,  Desert  and  Celtic  banks. 

Barrens  group,  Lovetown,  Tow  Hill,  Scotia,  Ackley, 
Lytle,  Red  bank,  Bull  bank,  etc. 

Pennsylvania  Furnace  and  College  group,  holding  Bry- 
son  bank,  Johnson,  Streuble,  Stover,  Puddington,  and  Big 
Hollow  banks. 

Perm's  Valley  group,  Watson,  Ross,  Sinking  Creek,  J. 
P.  Rankle,  Emerick,  etc. 

The  Pennsylvania  Furnace  mine. 

This  famous  ore  bank,  on  Spruce  creek,  in  Centre  county, 
close  to  the  Huntingdon  county  line,  has  been  mined  since 
1815.  Its  situation  in  respect  to  the  other  ore  mines  of  Nit- 
tany  Valley  is  shown  on  local  map,  Plate  XIV,  page  376, 
Fig.  2.*  A  special  map  of  the  mine  as  it  was  in  1873  is  on 

*T4,  1884,  Appendix  A,  p.  372.  Extracts  from  J.  P.  Lesley's  report  to 
Lyon,  Shorb  &  Co.,  in  1873.  All  figures  given  in  the  text  above  are  copied 
(reduced  to  I  linear)  of.  the  figures  in  T4.  They  will  serve  well  enough  as 
illustrations. 


PENNSYLVANIA    FURNACE   MINE.  379 

the  same  plate,  Fig.  3.  On  Plate  XV,  page  377,  Fig  1  is 
a  view  of  the  mine  from  the  top  of  its  S.  W.  wall ;  Fig.  2  is 
a  near  view  of  the  ribs  of  undecomposed  rock  in  the  pro- 
montory seen  at  the  edge  of  Fig.  1  ;  and  Fig.  3  shows  the 
height  of  the  wash  ore  in  the  walls. 

The  great  excavation  is  aboat  1400'  long  by  600'  wide  and 
60'  deep,  but  shafts  sunk  35'  to  a  permanent  water  level 
proved  that  other  and  even  better  ore  masses  lie  at  least  that 
much  deeper,  and  these  are  covered  by  undecomposed 
lime  rocks  dipping  40°,  S.  E.  as  seen  in  the  walls  of  the 
promontory  above. 

The  geologist  can  here  study  the  theory  of  the  formation 
of  the  Lower  Silurian  brown  hematite  ores  of  Pennsylva- 
nia to  great  advantage.  I  know  no  better  place,  and  few 
so  good. 

The  ores  are  evidently  not  washings  from  a  distance  ; 
neither  from  Tussey  mountain,  nor  from  the  present  sur- 
face of  the  anticlinal  ridge  ;  nor  from  any  formerly  existing 
surface  in  past  geological  ages,  when  the  surface  stood  at 
a  much  higher  elevation  above  sea  level.  They  are  evi- 
dently and  visibly  interstratih'ed  with  the  soft  clay  and 
solid  limestone  layers,  and  obey  the  strike  and  dip  of  the 
country  ;  the  strike  being  along  the  valley,  and  the  dip 
about  40°  towards  the  southeast. 

Thousands  of  minor  irregularities  prevail ;  the  streaks  of 
ore  and  masses  of  clay  are  wrinkled  and  bunched,  and  thin 
out  and  thicken  again  in  various  directions.  But  all  this 
irregularity  is  owing  to  the  chemical  changes  of  the  strata, 
and  to  the  changes  in  bulk  of  the  different  layers  during 
the  protracted  process  of  solution  and  dissolution,  during 
which  the  looser  calciferous  and  ferriferous  sandstone  lay- 
ers have  lost  their  lime  constituent,  packed  their  sand  and 
clay  more  solidly,  and  perhydrated  their  iron.  In  this  long 
process  cleavage  planes  have  been  widened  into  crevices ; 
caverns  have  been  excavated;  pools  or  vats  have  been  cre- 
ated ;  precipitates  of  massive  (rock  and  pipe)  ore  have  been 
thrown  down;  and  a  general  creeping  and  wrinkling  of  the 
country  been  effected.  But  the  original  general  arrange- 
ment or  stratification  has  been  preserved  ;  and  those  por- 


380  GEOLOGICAL   SURVEY    OF   PENNSYLVANIA. 

tions  of  the  whole  formation  which  had  but  little  lime 
have  been  left  standing  as  sandstone  strata  ;  while  others 
having  but  little  sand  remain  as  solid  and  massive  lime- 
stone strata;  those  which  had  an  excess  of  alumina  are  now 
in  the  condition  of  streaks,  masses,  or  layers  of  white  or 
mottled  clays  ;  and  only  such  as  were  properly  constituted 
clay-sand-lime-iron  deposits  (originally)  have  been  so  com- 
pletely dissolved  as  to  permit  the  lime  to  flow  off,  and  the 
iron  to  consolidate  into  ore. 

Every  stage  of  this  interesting  operation,  and  every  phase 
which  it  presents  in  other  parts  of  the  Appalachian  belt  of 
the  United  States  from  Canada  to  Alabama  may  be  seen 
and  studied  in  these  old  and  extensive  ore  banks  of  Penn- 
sylvania furnace. 

At  first  sight  of  the  bank  the  ore  deposit  looks  as  if  it 
were  a  grand  wash  or  swash  of  mingled  clay  and  fine  and 
coarse  ore  grains  and  balls,  occupying  hollows,  caverns  and 
crevices  in  the  surface  of  the  earth  and  between  the  solid 
limestone  rocks;  and  some  of  it  undoubtedly  has  been  thus 
carried  down  into  the  enlarged  cleavage  partings  of  the 
limestones ;  and  into  sinkholes  and  caverns  formed  by 
water-courses  ;  where  it  now  lies  (or  lay  when  excavated) 
banked  up  against  walls  or  faces  of  the  undecomposed  lime 
rock.  But  as  a  whole  the  ore  streaks  and  "main  vein"  of 
ore  must  occupy  nearly  the  places  originally  occupied  by 
the  more  ferruginous  strata  after  they  had  got  their  dip  and 
strike. 

The  ore  is  taken  out  with  the  clay,  and  hauled  up  an  in- 
cline by  means  of  a  stationary  steam  engine  at  its  head,  and 
dumped  into  a  large  washing  machine,  with  revolving 
screens  ;  whence,  after  the  flints  and  sandstones  have  been 
picked  out,  it  is  carried  on  an  ironed  tramway  to  the  bridge 
house  of  the  furnace. 

The  ore  forms  from  10  to  50  per  cent,  of  the  mass  exca- 
vated, and  the  small  amount  of  handling  makes  the  ore 
cheap. 

The  upper  ores  will  furnish  stock  for  yet  many  years. 
After  that,  or  in  case  more  furnaces  are  erected,  or  distant 
markets  calls  for  the  shipment  of  ore  by  railway,  deep  shafts 


PENNSYLVANIA   FURNACE   MINE.  381 

or  bore  holes  must  be  sunk  to  drain  the  underground,  and 
the  lower  ones  may  then  be  lifted  to  an  unknown  extent. 
The  prism  of  ore  in  siglit  in  1873,  calculated  roughly  from 
the  old  banks  and  new  cuts  and  shafts,  old  and  new,  in 
various  places,  contains  several  millions  of  tons  of  wash 
ore,  lump  ore,  and  pipe  (rock)  ore.*  But  the  unproven  ore 
ground  ranges  far  into  the  surrounding  lands.  A  large 
new  area  was  stripped  in  1873.  Large  quantities  of  ore  are 
left  between  the  limestone  ribs  in  the  walls  of  the  pit,  as 
shown  in  Figs.  33,  34.  The  limestone  ribs  dip  35°  to  40°,  S, 
35°  E.  on  the  range  of  natural  outcrops  shown  in  the  local 
map,  Fig.  37.  Slight  crumplings  of  the  limestone  vary  the 
dip  from  18°  to  65°  ;  but  these  are  due  either  to  movements 
in  the  yielding  ore  mass  or  to  a  deception  caused  by  mis- 
taking cleavage  planes  for  bed  plates.  No  such  variations 
are  apparent  at  a  distance  from  the  banks,  the  whole 
limestone  formation  descending  uniformly  beneath  the 
foot  of  Tussey  mountain  with  a  dip  of  something  under  40°. 

The  height  of  the  walls  of  the  various  excavations  may 
be  seen  by  reference  to  the  ten-foot  contour  lines  in  Fig,  37. 
These  also  show  that  the  ground  now  so  deeply  excavated 
once  formed  a  high  divide  between  a  vale  descending  south- 
west to  Spruce  Creek,  and  a  corresponding  but  shallower 
vale  descending  northeast  to  the  settling-dam  hollow.  It 
looks  as  if  the  ore  once  lilled  both  these  vales,  but  has  been 
swept  away  by  the  natural  drainage  into  Spruce  Creek, 
from  the  one  which  descends  in  that  direction,  and,  perhaps, 
from  the  valley  of  Spruce  Creek  itself,  down  to  and  beyond 
the- Furnace. 

The  entire  walls  of  the  cuts  are  of  wash  ore,  and  it  is 
all  torn  down  and  taken  to  the  washing  machine.  But 
the  tops  of  pyramids  of  solid  pipe  ore  are  exposed  in  the 
floor,  and  some  reached  to,  or  nearly  to,  the  sod  above. 
At  one  of  the  deepest  places  in  the  floor,  60  feet  below  the 
sod  a  shaft  was  sunk  40  feet  further  through  solid  pipe 

*  Proved  area  550  x450  yards,  which  at  15  yards  depth  gives  3^  millions  of 
cubic  yards,  affording  600,000  tons  of  washed  ore  ready  for  use.  Of  this  100,- 
000  have  been  smelted  into  50,000  tons  of  neutral  cold  blast  charcoal  iron  of 
the  best  quality. 


382  GEOLOGICAL   SURVEY   OF  PENNSYLVANIA. 

ore,  and  then  limestone,  and  was  stopped  by  water.  Water 
does  not  stand  in  the  present  floors  on  account  of  the  free 
circulation  at  a  still  lower  depth  through  crevices  and  cav- 
erns communicating  with  Spruce  Creek,  which  itself  issues 
from  a  cave. 

The  original  name  of  the  Pennsylvania  ore  bank  was  the 
Bryson  cut.  It  was  examined  again  by  Mr.  d'Invilliers  in 
1883,  who  found  it  little  changed  since  my  study  of  it  in 
1873.  At  that  time  (1883)  it  was  in  common  with  most  of 
our  mines  idle,  but  a  new  lease  promised  afresh  develop- 
ment of  it  under  better  auspices. 

The  HosJcer  bank  is  on  the  steep  N.  W.  dips  of  the  Gale 
Hollow  anticlinal  ridge,  so  low  down  in  II  as  to  be  2500' 
beneath  III.  The  Pennsylvania  ore  rocks  on  the  S.  E.  side 
of  the  ridge  and  dipping  40°  S.  E.  are  also  sandy  dolomites  ; 
but  above  them  lies  a  series  of  white  and  blue  limestones  ; 
and  above  all  lie  soft,  blue  and  dove  colored  Trenton  lime- 
stones dipping  18°  or  15°,  S.  E.  under  the  slates  of  III. 

The  Bryson  cut  ores  are  essentially  pipe,  finely  disinte- 
grated, and  occurring  in  every  conceivable  form,  whether 
in  streaks  of  ore  and  clay,  or  in  flattened  scales,  or  bunched 
with  sandy  limestone,  or  in  solid  pipe  masses  ;  but  every- 
where showing  a  tendency  to  interstratitication  and  point- 
ing to  their  probable  formation  in  place  by  the  dissolution 
and  leaching  of  the  limestone  rocks  and  the  filling  in  of 
cavities  with  mixed  sand,  clay  and  iron-ore.  Comparatively 
little  lime  has  been  left  in  this  ore,  showing  how  thorough 
dissolution  has  been  ;  and  the  percentage  of  magnesia, 
though  low,  is  probably  due  to  its  less  solubility  as  com- 
pared with  the  corresponding  lime  salt. 

Very  little  of  the  quartz  and  flint  grains  found  with  the 
ore  are  water-worn  or  rounded,  and  so  create  at  once  a 
marked  difference  between  these  ores  and  those  of  the  bar- 
rens in  the  Scotia- Juniata  range.  But  it  must  be  remem- 
bered that  these  latter  ores  are  much  lower  down  in  the 
measures.  When  visited  in  July,  1883,  no  work  had  been 
done  here  since  the  fall  of  1882,  when  Carnegie  Bros.  &  Co. 
returned  their  lease  of  the  property. 

The  Messrs.  Carnegie,  while  doing  some  little  mining  in 


PENNSYLVANIA   FURNACE  MINE.  383 

the  old  workings  south  of  the  washer,  turned  most  of  their 
attention  to  the  development  of  the  New  bank  located  east 
of  the  former  and  shown  on  map.  About  10  acres  in  all 
have  been  disturbed  here. 

Various  estimates  have  been  made  by  different  parties  of 
the  original  amount  of  ore  contained  in  this  deposit  (which 
roughly  measured  may  be  taken  a  t  500  yards  N.  W.  and  S. 
E.  and  350  yards  N.  E.  and  S.  W.)  which  vary  from  200,- 
000  tons  up  to  600,000  tons,  with  a  possible  output  of  even 
1,000,000  tons,  allowing  for  increased  depths  over  50  feet, 
etc.  All  such  estimates  are  greatly  affected  by  the  frequent 
occurrence  of  limestone  ledges,  clay  banks  and  lean  faces, 
and  are  in  every  case  when  carried  beyond  the  depth  of  the 
wash  deposit  and  into  the  solid  pipes  in  the  bottom,  merely 
speculative. 

The  average  wash  of  the  materials  is  about  1  to  8  or  9, 
which  will  give  1  ton  of  ore  to  each  6  or  7  cubic  yards  of 
material,  a  cubic  yard  of  ore  being  estimated  to  weigh  only 
1J  tons.  The  washers  occasionally  showed  a  record  of  one 
to  five,  but  this  was  when  mining  was  being  carried  on  in  ex- 
ceptional ground.  The  majority  of  the  more  recent  pits 
(some  outside  the  limits  above  given)  show  a  depth  of  only 
abou  1 10'  of  wash  ore,  under  which  clay  and  limestone  occur. 

The  old  charcoal  furnace  was  changed  in  1881  to  a  coke 
furnace  of  11'  at  bosh,  43'  high  and  8'  at  tunnel  head.  It 
was  not  successful.  The  incline  plane  was  abandoned  and  a 
narrow  gauge  railway  running  down  around  the  edges  of 
the  pit  was  substituted.  The  new  washers  had  a  capacity 
of  140  tons  daily  for  good  rich  ore.  The  difficulty  was  to 
separate  the  light  pipe  ore  from  the  heavy  flint ;  also  to- 
keep  the  flat  or  scaly  ore  from  floating  off  the  rig.  Boys 
had  to  pick  out  the  flints.  A  steam  excavator  was  tried  for 
stoping  down  the  walls  but  failed  on  account  of  project- 
ing noses  or  ribs  of  limestone. 

The  deepest  part  of  the  old  bank  has  been  nearly  ex- 
hausted of  cheap  ore,  and  show  several  outcrops  of  silicious 
sandy  dolomite,  very  much  broken,  but  dipping  southeast. 
This  rock  is  frequently  ore-bearing,  showing  occasionally 
streaks  from  one-sixteenth  to  several  inches  thick.  While 


384  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

occurring  in  the  center  of  the  deposit,  they  do  not  seem  to 
have  affected  the  ore  which  occurs  above  and  below  them 
and  frequently  interstratified  with  them.  Some  30  to  60 
feet  of  stripping  has  been  done  here,  but  shafts  sunk  from 
the  bottom  of  the  open  cut  30  to  40  feet  deeper  have  proved 
the  presence  of  good  ore  ground  as  yet  untouched.  In  the 
days  of  early  mining  here  tine  exposures  of  pipes  40'  high 
are  reported,  though  none  such  are  to  be  seen  to-day. 
The  best  ground,  when  last  visited,  seemed  to  be  along  the 
south  side  of  the  new  workings,  where  really  excellent 
wash  ore  still  remained  untouched  in  a  face  30'  high.  Good 
lump  ore  is  reported  all  along  the  bottom  of  these  workings, 
now  covered  with  tine  silt  and  mud,  and  in  any  future  work 
this  should  be  mined  with  the  wash  surface  ore  or  that  in 
the  east  end,  thus  making  a  cheap  and  rich  average  ore. 
All  the  work  so  far  has  been  done  above  ground,  the  floor 
being  usually  limestone. 

Dr.  Genth's  analyses  of  (1)  two  samples  of  amorphous, 
brown  compact  ore  mixed  with  ochreous  yellowish  or  red- 
dish ore,  some  of  its  cavities  lined  with  very  fine  coating  of 
fibrous  ore,  and  (2)  of  pipe  ore,  with  cavities  filled  with  fea- 
ruginous  clay,  were — Fer.  ox.,  81.55  (83.74) ;  mang.  ox., 
0.10  (0.31) ;  cobaltic  ox.,  a  trace  (a  trace)  ;  alumina,  1.49 
(0.33) ;  magnesia,  0.47(0.34) ;  lime,  a  trace  (a  trace)  ;  phos. 
acid,  0.16  (0.14) ;  sil.  acid,  2.98  (2.57) ;  quartz,  1.55  (0.44) ; 
water,  11. 70  (12. 13) ;  thatis7r<w,  57.10(58.62) ;  Phosphorus, 
0.07  (0.06) ;  or  phosphorus  in  100  parts  iron,  0.12  (0.10). 

Dr.  Genth's  analysis  of  the  sand  rock  ribs  was:  Ferr. 
ox.,  43.65  ;  mang.  and  cob.  ox.,  1.55 ;  al.,  2.43 ;  mag.,  1.64 
lime.  0.12  ;  phos.  acid.  0.27  ;  sil.  acid,  5.19  ;  quartz,  36.52  ; 
water,  8.63.  It  contained,  therefore,  30  per  cent,  of  iron.* 

*  "  The  above  analyses  show  besides  the  mechanically  admixed  rounded 
grains  of  sand,  which  I  distinguish  as  'quartz',  a  considerable  quantity  of 
silicic  acid,  which  is  in  chemical  combination,  probably  as  a  hydrous  ferric 
oxide.  But  as  it  is  impossible  to  say  what  the  true  character  of  this  min- 
eral may  be,  whether  authosiderate,  or  degeroaite  a  silicate  of  the  composi- 
tion Fe2O3,  2SiO2-j-3H2  O  or  a  species  not  yet  known  in  its  pure  state,  suffice 
it  to  say  that  all  these  ores  are  mechanical  mixtures  of  limonite  with  hy- 
drous ferric  silicate  and  minute  quantities  of  hydrous  ferric  phosphates, 
perhaps  dufrenite  or  cacoxenite ;  some  of  the  ores  contain  beside  these, 


PENNSYLVANIA   FURNACE   MINE.  385 

Dr.  Genth  recognizes  three  varieties  of  limestone  in  this 
bank,  and  the  results  of  his  analyses  are  as  follows  : 

No.  1.  Upper  limestone,  dark  gray,  compact,  slightly 
crystalline.  The  atomic  ratio  between  the  magnesia  and 
lime  is  1 : 15. 

No.  2.  Pale  ash  .gray,  very  finely  crystalline,  rough  to 
the  touch  like  rotten  stone,  very  friable  and  easily  falling 
to  powder,  a  true  dolomite.  Atomic  ratio  between  mag- 
nesia and  lime,  1  :  1. 

No.  3.  Yellowish  gray,  soft,  rotten,  feels  rough  to  the 
touch,  sandy  ;  crystalline  ;  has  a  laminated  structure  ; 
also  a  dolomite.  Atomic  ratio  between  magnesia  and  lime, 
1:1.08.* 

small  quantities  of  manganese  ores,  mostly  the  so-called  '  bog-manganese' 
or  wad,  but  also  pyrolusite  and  Psilomelane. 

"It  is  a  very  remarkable  fact  that,  although  these  iron  ores  are,  to  a  great 
extent  at  least,  the  result  of  the  decomposition  of  limestones  and  by  them 
precipitated,  that  almost  the  entire  amount  of  lime  has  been  washed  out  of 
them  and  only  traces  are  remaining  ;  of  the  second  constituent  of  the  lime- 
stones, the  magnesia,  a  somewhat  larger  quantity  is  left  behind,  owing  un- 
doubtedly to  the  lesser  solubility  of  its  carbonate  in  carbonic  acid  water." 
(Dr.  F.  A.  Gen.,  T3,  p.  434.) 

*  Dr.  Genth's  analysis  of  a  4'  bed  of  limestone  capping  33'  of  pipe  ore  in  the 
Hostler  bank  (T3,  p.  435)  shows  that  it  too  is  a  true  dolomite,  but  holding 
4.33  of  quartz  and  silicic  acid.  He  adds  (p.  436)  :  "  It  is  remarkable  that 
the  limestones  and  dolomites,  of  which  I  give  the  analyses,  contain  almost 
the  entire  amount  of  silicic  acid  as  quartz ;  only  a  small  quantity  is  present 
as  soluble  silicic  acid  and  in  combination  with  alumina.  If  the  limestones 
and  dolomites  are  dissolved  in  acid,  the  quartz  remains  often  as  a  scoriaceous 
mass  or  in  irregular  sandy  but  not  rounded  or  water-worn  grains  ;  some- 
times it  forms  large  coherent  slaty  masses  in  the  limestone,  frequently  filled 
with  minute  cavities,  previously  occupied  by  rhombohedral  crystals  of  dol- 
omite. Similar  pieces  found  in  the  Pennsylvania  bank  are  white  like  por- 
celain and  show  the  same  cavities  of  rhombohedral  crystals.  Other  varieties 
of  limestone  in  the  Pennsylvania  bank  have  a  still  greater  admixture  of 
quartz  and  are  a  real  calciferous  sand  rock." 

(1)  (2)  (3) 

Carbonate  of  iron, 1.31  0.45  .118 

"          "    manganese, 0.18  0.06  trace. 

"          "    magnesia, 3.98  42.39  35.51 

«          «    lime, 72.67  51.25  45.73 

Quartz  and  silicic  acid, 18.05  5.03  15.83 

Alumina, 3.81  0.82  1.75 

Total, 100.00  100.00  1QQ.OQ 

Metallic  iron, 0.63  ~  0.22  0.57 

Magnesia, 1.90  20.19  16.91 

Lime, 40.69  28.70  25.61 

25 


386  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA 

Dr.  Henderson  before  his  death  sent  me  a  cross-section, 
which  he  had  made  on  his  own  farm  4m.  N.  E.  of  the 
Pennsylvania  bank,  see  Fig.  1,  plate  XIV.  By  his  calcula- 
tion the  Pennsylvania  ore  horizon  lies  2200'  beneath  No. 
Ill,  with  another  ore  horizon  300'  above  it,  and  a  third  one 
800'  above  it ;  that  is,  only  1400'  beneath  No.  III. 


NITTANY  VALLEY,  HUNTINGDON  CO.  ORE  MINKS         887 


CHAPTER  XXXIII. 
Nittany  valley,  Huntingdon  county  ore  mines. 

Before  describing  the  banks  I  must  continue  the  struct- 
ure of  Nittany  valley  through  Huntingdon  county  to  the 
little  Juniata  river.  A  few  words  and  the  accompanying 
cross-sections  on  plate  XI Y  will  suffice.* 

If  my  cross-section  along  Warrior's  Run  (T3,  Fig.  3)  be 
correctly  drawn  it  exhibits  four  ore  horizons  rising  to  the 
surface,  one  after  the  other,  from  S.  E.  to  N.  W.,  their  out- 
cropping rocks  making  parallel  belts  of  ore  banks,  and  their 
respective  depths  geologically  beneath  the  bottom  of  for- 
mation III  being  as  follows  : 

Trenton  limestone,  etc.,  etc. 
Pennsylvania  and  Gale  Hollow  banks, 2500' 

Barren  interval,  700'. 
Huntingdon  furnace  ore  banks, 3WO' 

Barren  interval,  550'. 
Tollgate  pipe  ore  range, 3750' 

Barren  interval,  1500'. 
Pennington,  Town,  Loveiown  banks, 5250' 

*The  cross-sections  in  T3,  Figs.  1,  2,  3,  pp.376,  378,  380,  embody  my  views 
of  the  structure  after  my  private  survey  of  the  legion  for  Lyon,  Shorb  &Co. 
in  1872.  I  was  assisted  in  a  contour  line  survey  of  it  by  Mr.  Franklin  Platt, 
from  whose  field  notes  the  contoured  map  was  plotted  and  drawn  and  the 
ore  banks  located.  In  1882,  during  the  progress  of  the  state  survey,  my 
topographical  assistants,  Mr.  E.  B.  Harden  and  Mr.  O.  B.  Harden,  surveyed 
and  mapped  that  most  troubled  and  obscure  part  of  the  valley  lying  east  of 
Tyrone  forges  and  Birmingham  to  get  the  faults  in  Bald  Eagle  mountain, 
and  the  true  location  and  character  of  the  Nittany  axis  in  Pennington  ridge. 
The  following  year  Mr.  d'Invilliers  went  over  the  ground  in  furtherance  of 
his  own  work  in  Centre  county  ;  and  his  criticisms  on  my  sections  of  1872 
will  be  found  in  the  report  on  Huntingdon  county,  T3,  pp.  443  to  445,  his 
chief  objection  being  to  my  little  Logan  creek  synclinal,  as  he  would  prefer 
to  consider  the  S.  E.  dips  along  Logan  creek  as  overturned  N.  W.  dips.  Nor 
am  I  at  all  positive  that  my  original  construction  of  the  rise  of  the  limestone 
mass  over  the  Bald  Eagle  mountain  at  the  Tyrone  gap  is  the  correct  one, 
although  my  observations  along  Logan  creek  were  long,  close  and  carefully 
studied,  and  my  section  was  drawn  in  full  view  of  the  fact  that  a  downward 
brush  of  the  edges  of  the  limestones  against  the  opposite  (N.  W.)  side  of  the 
fault  was  rather  to  be  expected. 


388  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 


Cratt  faction^  in 


Ti.  xvr 
Co. 


NITTANY  VALLEY   ORE   BANKS. 


Jftttany  "VaUey. 
topographical  sketch,  ntcyy  in&O'contours  made  in  1873 

locating  the  Ore  t&anks  &f zHountingctcn  aTitf  Centre  GPJ 
Jieldurork  6y  FWcttb. 


GEOLOGICAL   SURVEY    OF   PENNSYLVANIA. 

Pennington  range  in  Huntingdon  County. 

The  lowest  range  of  ore  banks  is  described  in  T3,  p.  388  ; 
and  pi.  XIV,  f.  8,  gives  their  arrangement.*  It  commences 
2  m.  from  the  Jtiniata  and  runs  2  miles  to  the  RR.  1  m.  W. 
of  Warrior  Mark  village  ;  the  N.  W.  face  of  the  ridge 
covered  with  wash  ore,  underneath  which  lie  sheets,  belts, 
and  masses  of  rock  ore  between  ribs  of  undissohed  lime- 
sand  rock,  with  inter  stratified  beds  of  lime-shales  turned 
into  white  clay.-\ 

That  rich  ore  masses  descend  N.  W.  in  a  series  of  ir- 
regular but  continuous  floors  and  layers  between  the  clay 
beds  was  proved  by  the  gallery  work  driven  in  wavy  ore. 
Great  quantities  of  salable  ore  and  wash  ore  also  existed.:}: 

The  main  open  cut  700'xlOO'xl5'  to  25'  deep  has  wash  ore 
walls,  15'.  A  shaft  struck  (at  15')  manganese  ore  5'.  In  this 
pit  stands  a  solid  rib  of  half  decomposed  limy-sandstone 
strata,  carrying  more  or  less  ore,  dipping  gently  N.  W.  ; 
bunches  of  good  ore  in  ferruginous  sandstone.  It  is  an 
admirable  place  to  study  the  genesis  of  our  limonite  ores. 

The  West  Pennington  bank  (Fig.  10),  £  m.  from  the  last, 
550'xl20'  is  wholly  in  wash  ore  ;  yielded  richly  for  7  years 
as  an  open  cut  to  a  depth  of  40';  then  worked  by  galleries 
(Fig.  12).  Another  open  cut  200'  further  west,  300'x45'x  25' 
deep  (once  much  deeper)  in  wash  ore.  Another,  400'  fur- 

*  The  Pennington  ridge  anticlinal  loses  itself  in  the  hill  N.  of  Warrior 
Mark  village  and  in  the  great  fault  further  on.  Obscure  dips  of  80°,  N.  W. 
in  limy  sandstone  500  yards  N.  W.  of  the  village,  might  very  well  be  mis- 
taken for  30°  to  60°  S.  E.  dips  on  account  of  the  innumerable  cleavage 
planes ;  but  80°,  N.  W.  dips  are  seen  in  blue  limestone  450  yards  further 
up  Warrior  Run.  All  the  outcrops  N.  E.  of  Warrior  Mark  village  belong 
to  the  S.  E.  side  of  the  Pennington  ridge  anticlinal,  as  any  one  can  see  who 
travels  along  the  road  to  Lovetown.  Therefore  the  Pennington  ore  range 
is  a  short  one  ;  but  the  next  ore  range  to  the  S.  E.  of  it  runs  on  through 
Warrior  Mark  village  and  Lovetown  into  Centre  county. 

f  Fig.  9  is  a  reduced  copy  of  Booking's  map  of  the  underground  tunnel 
workings,  shafts,  etc.,  in  the  Old  or  East  bank.  Water  stopped  most  of  the 
old  mining.  One  old  shaft  30'  deep  was  deepened  to  60'  and  struck  the 
sandstone  floor.  Another  shaft  in  1865  reached  the  ore  bottom  at  45°.  For 
further  details  see  T3,  p.  392. 

{Thus  the  first  pit  near  the  RR.  200'x50'xl5  deep  yielded  5000  cubic  yards 
of  wash  ore  without  solid  lump.  Shaft  No.  1  near  it  went  through  top  wash 
15',  rich  lump  5',  barren  clay  25',  good  lump  15'.  Shaft  No.  2,  lean  ore  on 
top,  clay  to  40',  good  lump  10'. 


NITTANY    VALLEY  ORE  BANKS.  391 

ther  west  (Old  Phillips'  bank),  300'x90'x20';  once  deeper 
and  drained  by  a  tunnel.  420' long.*  The  Beck  bank,  %  m.  N. 
E.  of  old  Pennington  bank,  is  120'x60'xl5'  deep.  The  New 
Town  bank  (also  Beck' s],  1  m.  further  N.  E.,  stopped  by 
water,  ore  in  floor. 

Warrior  Mark  and  Lovetown  range. 

From  Warrior  run,  N.  E.,  we  have  almost  a  continuous 
series  of  shafts  and  open  cuts  on  thes  ame  lowest  lime- 
sand  horizon  as  the  Pennington,  but  on  the  S.  E.  dip  ; 
thus — 

Old  Town  (i  m.  E.  of  Warrior  run)  ;  Romberger' s  (1£)  ; 
Hannah  (If) ;  Waiters  (2i) ;  Braunstetter' s  (2f)  with  pipe 
ore  outcrops  to  the  S.  E.  of  it ;  Disputed  (4f )  ;  Hannah 
furnace  (5)  ;  Hannah  furnace  and  Beck  (£  m.  N.  of  the 
last  two,  and  less  than  a  mile  W.  of  Lovetown)  ;  Pipe  ore 
pits  (^m.  S.  of  Lovetown)  ;  8aw  mill  ore  crops  (2  m.  N.  E. 
of  Lovetown)  ;  Hannah  furnace  and  Bryan  (2f ) ;  Curtin 

(5).f 

The  ores,  when  rich,  are  black  or  very  dark,  much  of  it 
pitchy  lustrous,  often  inclining  to  cold  shortness;:}:  the 
leaner  ore  of  a  lighter  brown  ;  clay  predominating  over  sand 
in  the  deposits  ;  perhaps  some  of  them  somewhat  higher  in 
II  than  the  Pennington,  but  still  very  low  in  the  formation. 

Dry  Hollow  range  in  Huntingdon  County. 

Under  this  head  in  T3,  pp.  404  are  described,  figured  and 
mapped: — Pond  bank  No.  2;  Wryebank;  Old  Sandy; 

*This  range,  with  its  lean  layers  and  sand  masses  so  low  in  II  (Cal.  SS.), 
"holds  purplish,  easy  smelting  ore,  mixed  with  day  and  without  discerni- 
ble regular  veins"  (Booking) .  Plenty  of  wash  ore  ;  but  dry  screening  im- 
possible. It  is  evident  that  a  vast  quantity  of  ore  is  still  to  be  won,  but  it 
can  only  be  won  by  scientific  stoping  and  washing.  The  extensive  dry 
tailings  covering  the  slope  north  of  the  cuts  can  be  profitably  washed  and 
got  out  of  the  way  of  deep  mining  (J.  W.  Harden).  When  powerful  pump- 
ing machinery  is  employed  many  hundred  thousand  tons  will  be  won  at  a 
market  profit 

t  Their  descriptions,  with  local  map  figures,  can  be  found  in  my  report 
embodied  in  report  T3,  pp.  400  to  404.  The  description  of  the  Lovetown 
banks  will  be  found  in  T4,  pp.  354  to  360,  with  local  map  Figs.  20  to  25. 

}  See  Dr.  F.  A.  Genth's  analyses  in  T3,  pp.  427,  429. 


392  GEOLOGICAL    SURVEY   OF   PENNSYLVANIA. 


Tl.  XV//I 


JVittany  Yalley  Unwnjh  ore  lanfa .  1873. 


NITTANY   VALLEY   ORE   BANKS. 


393 


£1    XJX. 


y  Tafley  ore  banks  inffiuntinydon  Co. 


394  GEOLOGICAL   SURVEY    OF   PENNSYLVANIA. 

Simpson's;  Dixort s ;  Litlle  Dry  Hollow ;  Dry  Hollow; 
Old  Red  bank;  Bean  bank ;  Bressler's* 

The  great  breadth  of  the  Dry  Hollow  belt  is  sufficient 
evidence  that  it  covers  more  than  one  geological  horizon  ; 
and  to  this  is  added  another  proof,  the  different  character 
of  the  ore  in  (for  example)  the  Pond  and  Wrye  banks.  It 
is  quite  certain  that  the  banks  of  this  group  or  belt  are  in 
geological  range  with  the  Kerr  and  Bredin,  Hosker,  and 
Pennsylvania  Furnace  banks. 

Cale  Hollow  range  in  Huntingdon  county. 

This  is  separated  from  the  Dry  Hollow  range  by  Hickory 
ridge  and  its  ores  lie  in  a  deeper  and  narrower  trough,  but 
at  the  outcrops  of  the  same  rocks,  therefore  of  the  same 
horizon,  and  of  the  same  character,  except  that  an  abun- 
dance of  pipe  ore  has  been  mined  from  Cale  Hollow  and 
very  little  from  Dry  Hollow. 

The  banks  of  this  range  described  in  T3,  p.  413,  are  the 
Kerr  and  Bredin  bank,  of  high  reputation  for  its  "gun 

*  I  can  only  extract  a  few  sentences  of  most  note,  and  refer  the  reader  to 
the  reports.  In  the  Wrye  bank  an  old  miner  said  they  went  through  worth- 
less wash  ore  26'  and  then  18'  good  lump  ore,  and  still  in  the  floor,  What 
the  charcoal  furnace  men  called  worthless  is  now  valuable  to  hot  blast  coke 
and  anthracite  furnace  men.  It  is  also  reported  that  the  top  of  the  ore 
mass  at  one  place  sank  to  50',  thinned  away  and  rose  again.  Rich  solid  ore 
still  stands  45'  beneath  the  surface.  In  Jos.  Kreider's  fields  the  surface 
show  indicates  a  heavy  mass  of  rich  solid  ore  underground. — The  Dry  Hol- 
low pits  occupy  a  great  space  and  have  had  formerly  a  great  output ;  mostly 
of  fine  wash  ore  in  clay ;  shafts  going  down  60'  through  wash  and  lump 
ore,  and  always  drowned  out  for  want  of  adequate  pumping  power;  only 
the  lump  ore  marketed,  the  small  wash  ore  despised.  The  connection  of 
Dry  Hollow  with  Red  Bank  solid  ore  ground  under  the  surface  wash  is  cer- 
tain. The  RR.  cut  exposes  wash  ore  for  300'  or  400',  in  some  places  10' 
thick  resting  on  clay,  in  other  places  20'  or  25'  thick  holding  large  lumps  of 
solid  ore.  The  varying  thickness  of  the  red  clay  and  ore  layers  in  these  ex- 
posures teaches  the  meaning  to  be  drawn  from  the  miners'  trial  shafts. 
Some  of  the  solid  lumps  weigh  300  or  400  Ibs.  Very  few  chert  fragments  are 
seen  ;  in  fact  this  exposure  shows  less  silica  than  any  other  in  the  valley. 
Little  or  no  soil  covering  exists. — At  Bean  bank  the  surface  ore  lumps  were 
lifted  and  sent  to  Huntingdon  furnace  ;  and  it  is  the  practice  elsewhere  ;  no 
attention  paid  to  the  great  body  of  wash  ore  ;  no  effort  to  mine  to  the  deep; 
consequently  a  vast  amount  of  ore  ground  awaits  future  exploration  and 
excavation,  even  within  a  mile  of  the  railroad.  (T3,  412.) 


NITTANY   VALLEY   ORE   BANKS.  395 

metal  ore,"  much  resembling  that  of  the  Bloomtield  banks 
in  Morrison's  cove,  Blair  county.* 

The  wash  ore  ground  continues  along  Hickory  ridge. 
Bronsteiter 's  pits  are  1£  ni.  W.  To  the  east  it  continues 
to  Little  bank  in  Half  Moon  run,  with  dips  of  20°,  &c.,  S. 
30°  E. 

The  Hostler  bank  on  the  N.  W.  slope  of  the  Spruce 
Creek  anticlinal,  2  m.  S.  W.  of  Pennsylvania  furnace  which 
used  the  ore ;  a  large  open  cut  in  "pipe"  wash  ore  (some- 
times mixed  with  lump)  60'  and  65'  deep,  in  all  the  shafts  ; 
one  of  which  struck  (at  65')  solid  limerock  10"  to  2'  thick  ; 
below  which  pipe  ore  45'  deep. 

It  is  a  constant  and  important  feature  of  the  pipe  ore 
banks  of  the  southeastern  ore  range,  that  they  do  not 
exhibit  the  so-called  lean  ores  of  the  lower  geological 
horizons  in  the  ore  ranges  to  the  N.  W.  of  it,  in  the 
Barrens,  &c.  It  has  been  the  uniform  experience  at  the 
Hostler,  Pennsylvania  and  other  pipe  ore  banks  that  shafts 
and  borings  have  always  passed  through  lump  ore  after 
having  been  sunk  or  drilled  below  water  level  ;  but  never 
reached  its  bottom  because  they  could  not  be  kept  clear 
of  water  owing  to  deficient  pumping  power.  The  under- 
ground drainage  all  through  the  valley  is  immensely  co- 
pious, and  the  largest,  deepest  bodies  of  heavy  ore  are  yet 
to  be  won  by  better  mining. f 

Red  bank,  and  several  old  pits,  lead  on  N.  E.  to  Little 
bank,  If  m.  W.  of  Penn  furnace.  Eyef 's  bank  is  a  mile 
further  on  on  the  E.  side  of  Half  Moon  run.  Then  (across 

*  Analysis  by  Dr.  Ge'nth:— Ferric  oxide,  70.67  (as  compared  with  Dr. 
Wuth's  analysis  of  Bloomfield  ore,  78.63);  man g.  ox.,  0.36  (mang.  0.29); 
cobaltic  ox.  a  trace  ;  alumina  3.91  (2.50);  magnesia,  0.26  (0.38);  lime,  a  trace 
(0.34);  phos.  acid,  0.19  (0.134);  sil.  acid,  5.48  (7.02)  ;  quartz,  680;  water,  12.33 
(10.71).  The  extra  quartz  in  Dr.  Genth's  analysis  lowers  the  p.  c.  of  iron  to 
49.47,  as  compared  with  Dr.  Wuth's  55.04  (T3,  413). 

|T3,  417,  quoting  J.  P.  L.  in  report  of  1872.  Mr.  Booking  writes  that  35' 
ore  will  pay  well  for  stripping  65'  to  75'  of  overclays.  The  Hostler  pits 
measure  360'xl50'x30'.  The  ore  lies  in  clays  separating  ribs  of  undecomposed 
limestone.  The  clays  are  mouldered  lime  shale  partings  between  solid  lime- 
stones. Shafts  more  recently  sunk  went  through  alternate  ore  clays  and 
limestone  ribs,  dipping  38°  N.  35°  W.  In  the  N.  W.  shaft  75'  wash  ore  lay 
on  the  first  solid  limestone.  The  wide  flat  part  of  Cale  Hollow  was  20  years 
ago  after  many  years  of  "ground-hog  mining"  still  a  virgin  district. 


396  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 


NITTANY   VALLEY   ORE   BANKS. 


397 


398  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

a  divide)  the  ore  follows  Tadpole  run  in  Sleepy  Hollow  at 
the  head  of  the  Beaver  dams  ;  then  the  dry  hollow  beyond 
is  a  repetition  of  Gale  Hollow ;  and  so  the  outcrops  con- 
tinue to  McAllister's  and  School  House  cross  roads,  8  miles 
from  the  Hostler  bank.* 

The  pipe  ore  horizons  have  a  geological  range  of  at  least 
1250'.  This  is  conclusively  proved  by  a  careful  section  of 
exposures  along  Warrior  Mark  run  above  and  below  the 
Old  Seat  bank,  ty  m.  S.  E.  of  the  RR.  bridge  over  the  run.  f 

Huntingdon  furna ce  banks. 

Within  a  circle  of  two  miles  radius  around  the  furnace, 
among  10°  S.  E.  dipping  rocks,  are  the  Wilson  bank  ;\  the 
Keefer  banks  ;  the  Dorsey  banks  ;§  whole  length  of  ore 
ground,  6000'  ;  maximum  breadth,  1500' ;  in  prolongation 
of  the  Dry  Hollow  range  before  described,  and  in  all  re- 
spects for  mining  purposes,  resembling  it.  Much  lean  ore 
is  mingled  with  the  rich,  and  much  dead  stripping  is  re- 
quired ;  but  the  liver  colored,  sandier  ore  lies  on  the  N. 
W.  side  of  the  belt,  up  the  hill  side,  lower  in  geological 

*  Beyond  this,  towards  Pine  Grove  mills,  the  old  Weaver  banks  are  not 
regular  pipe  ores,  but  the  liver  colored  red  short  ores  of  lower  horizons 
brought  to  the  surface  of  the  broad  plateau  by  the  Brush  Valley  anticlinal 
(T3,  420). 

f  See  full  description  T3,  422.  Beginning  at  the  mouth  of  Gale  Hollow,  1  m. 
E.  of  Huntingdon  furnace,  an  old  pipe  ore  bank  shows  50°  N.  W.  (another  dip 
is  38°).— At  2000'  N.  W.  the  dip  is  12°  S.  E.— At  3300'  the  Old  Scat  bank 
worked  the  same  pipe  ore  horizon  ;  abandoned  for  lack  of  pumping  power  ; 
ore  lean,  liver  colored,  like  Pennington,  but  no  sandstone  ;  a  good  deal  of 
flint,  however,  as  at  Pennsylvania.— 1800'  furtherup  run  limestone  9°,  S.  E.— 
900'  further  sandy  limestone  10°  S.  E.— 1500'  further,  pipe  ore  plowed  up. 
Pipe  ore  horizon,  No.  2,  700'  geologically  lower' than  Old  Seat  horizon. — 1500' 
further,  sandy  limestones,]13°,  S.  E. — 3000'  to  tollgate,  no  dips  exposed,  but, 
no  doubt,  all  gentle  S.  E. — 1500'  S.  W.  of  tollgate,  therefore  on  strike,  old  de- 
serted pipe  ore  bank  ;  Pipe  ore  horizon.  No.  3,  550'  below  No.  2,  or  1250'  below 
No.  1.— From  tollgate  2400'  up  run  to  RR.  bridge  ;  1200'  furtherup,  .Bec&and 
Town  banks,  dips  in  interval  20°,  35°,  etc.,  S.  E.  ;  therefore,  their  Penning- 
ton range,  non-pipe  ore  horizon,  is  geologically  2500'  to  3000'  beneath  the 
Cale  Hollow  pipe  ore  horizon,  No.  1,  above. 

J  Here  surface  ore  clays  lie  on  limestone  beds  which  cover  lime  sandstones. 

§  Three  miles  N.  E.  of  Juniata  river  at  Barree  Forge.  One,  200'x75'x20'  ; 
another,  225'x90'xl2' ;  another,  600' x210'x45' ;  in  places  much  deeper,  and 
wholly  in  wash  ore,  merely  uncovering  the  solid  ore  in  the  floor. 


SINKING    VALLEY    MINES.  399 

horizon  ;  and  the  pipe  ore  lies  down  hill,  S.  E.  geologically 
higher,  among  the  non-siliceous  magnesian  limestones. 

Sinking  Valley  mines. 

These  are  on  the  Blair  county  side  of  the  Little  Juniata. 

Dark  colored  lime-slate,  apparently  graphitic,  crops  out 
near  Birmingham,  and  near  the  axis  of  the  great  Nittany 
anticlinal  ;  therefore  fully  5000'  beneath  III.* 

The  McCahan  shafts,  %  m.  S.  W.  of  Birmingham,  and 
on  the  same  geological  horizon,  won  rich  good  pipe  ore  en- 
closed in  sand,  although  there  is  a  little  yellow  clay  with 
the  ore  ;  the  black  lime  slate  is  at  the  bottom  of  the  shaft. 

The  Robeson  pit,  2  m.  S.  S.  W.  of  Birmingham  100'x20'x- 
20' is  in  Col.  Gralbraith's  fields,  where  4  or  5  acres  are  cov- 
ered with  a  great  ore  show.  Ore  on  the  Gunnison  farm 
also. 

*The  same  black  slate  appears  on  the  Cogan  farm  1  m.  N.  E.  of  Birming- 
ham. The  wash  ore  lumps  in  clays  are  all  water-worn.  Analysis  of  ore  in 
T,  246. 


400  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 


Jfittany  and  Ganoe  valleys.  Their  Jhitidinals  and  yMiJU 


fault  at  Spruce  creek  gap  of  Ihsse^mtn. 
a2  Section . 


Fault  at  Port  Clinton  gap  of/fi&aUsiny  mtn 


CANOE   VALLEY.  401 


CHAPTER  XXXIY. 
Canoe  Valley  and  Morrison's  Cove   limestone  and  ore. 

Canoe  valley  is  not  so  much  a  southward  continuation  of 
Nittany  valley  as  it  is  a  long  side  gallery  leading  from  the 
grand  hall  of  Nittany  valley  into  the  closed  chamber  of 
Morrison's  Cove.  A  very  sharp  and  very  high  anticlinal 
wave,  ending  northward  in  a  fault,  lifts  about  5000'  of  No. 
II,  between  terrace  walls  of  III  and  crests  of  IV,  broken  by 
the  two  Juniata  river  gaps  ;  Tussey  mountain  on  the  S.  E. 
and  Canoe  mountain  on  the  N.  W. 

Along  the  foot  of  the  Canoe  mountain  terrace  runs  Jack- 
son's fault,*  which  at  the  Juniata  water-gap  above  the  town 
of  William sburg,  throws  the  Trenton  limestone  3000' 
against  the  Medina  sandstone,  lapping  them  horizontally 
past  each  other,  and  separating  thus  Short  mountain  from 
Canoe  mountain.  The  fault  and  the  anticlinal  axis  converge 
eastward  at  an  angle  of  about  15°  and  die  a  little  beyond  the 
Little  Juniata. 

Another  fault  runs  along  the  south  edge  of  Canoe  valley, 
and  is  an  interesting  study  in  a  topographical  sense,  because 
it  has  determined  the  course  of  the  river  and  the  place  of 
its  water-gap  at  Waterstreet ;  cutting  off  another  "Short 
Mountain,"  between  the  two  rivers,  f  This  is  the  fault 
struck  in  Spruce  Creek  Tunnel  on  the  line  of  the  P.  R.  R. 
It  throws  the  middle  beds  of  II  up  against  the  middle  beds 
of  III  in  the  gap  at  Spruce  Creek  Tunnel  ;  but  being 

*  Studied  and  described  by  him  in  1838,  but  wrongly  located  in  direction 
and  length  until  our  instrumental  surveys  of  1876  and  following  years,  at 
which  time  1  extended  it  to  the  Little  Juniata  at  Spruce  creek  station  and 
discovered  its  real  relation  to  the  central  anticlinal.  See  my  small  reduced 
sketch  mapinTS,  plate  LXIV,  page  346,  reproduced  on  a  still  further  re- 
duction in  this  volume,  plate  XXII.  fig.  1. 

f  Fig.  4  shows  the  curious  and  beautiful  topography  of  the  Narrows,  and 
the  narrow  throat  of  the  Canoe  valley  at  the  Little  Juniata.     Here  the  anti- 
clinal is  destroyed  by  the  fault ;  as  shown  in  Fig.  5,   at  the    bottom   of  the 
plate,  along  section  on  line  of  Little  Juniata. 
26 


402  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

oblique  to  the  valley  strike,  it  carries  the  top  of  II  against 
IV  by  an  horizontal  slide  movement,  so  as  to  enclose  a  tri- 
angular point  of  III  between  them  ;  as  shown  in  the  ver- 
tical section  and  horizontal  ground  plan,  fig.  2,  on  plate 
XXII.  * 

In  Canoe  Valley  proper  are  the  old  Clark  mine,  1  m.  S. 
of  Etna  furnace ;  the  old  Etna  mine,  2£  m.  N.  of  Will- 
iamsburg  ;  the  Brower  mine,  3  m.  N.  W. ;  the  Short  Moun- 
tain mine,  2%  m.  N.  W.  (and  H  m.  N.  of  Franklin  forge); 
Dean's  bank,  If  m.  S. ;  Patterson 's  bank,  1£  m.  S.  W.;  and 
the  Williamsburg  M.  Co"  s  Red  Ore  mines.  If  m.  S.  W.  of 
William  sburg.f 

*  I  have  added  (as  fig.  3)  a  vertical  section  of  the  fault  in  Schuylkill  county 
for  comparison,  and  have  reversed  it  (N.  for  S.)  in  order  to  make  the  com- 
parison easier  for  the  eye. 

f  Described  and  figured  in  T,  pp.  231  to  244.  The  figures  are  reproduced, 
reduced  to  half  size,  on  plate  XXIIL— The  Clarkmine,  small  and  long  aban- 
doned ;  ore  rather  red  short. — The  Etna  bank,  on  the  central  barren  sandy 
ridge,  1200'  above  tide,  400'  above  the  river  level,  looks  down  Irom  the  N. 
point  of  the  ridge  upon  an  amphitheatre  of  cultivated  country  150'  below  it; 
5000'  geologically  below  III ;  abandoned  years  ago,  1000'x200'x50'  deep  ;  ex- 
ceedingly rich  wash  ore  (not  water  worn)  ;  much  manganese  ore  in  sporadic 
irregular  layers  ;  shafts  112'  deep  said  to  have  worked  rich  lump  ore  ;  water 
totally  wanting. — The  Broiver  mine,  150'x50'x20',  now  abandoned  ;  on  central 
sandy  barren  ridge ;  walls  all  sand,  no  clay  visible ;  many  masses  ot  con- 
glomerated angular  flint  fragments  cemented  with  iron  ore,  and  many 
great  masses  of  sandstone  and  flint  coated  with  ore,  as  at  Springfield  mine  : 
no  limestone  fragments  visible.  Limestone  strata  between  it  and  the  Canoe 
mountain  dip  west,  and  if  it  were  not  for  Jackson's  fault  the  ore  horizon 
would  be  only  2500'  beneath  III,  as  given  in  the  text  of  T,  p.  241 ;  but  this  is 
a  great  mistake,  for  the  ore  is  evidently  the  Springfield  and  Etna  ore,  and 
we  must  understand  that  2500  of  II  are  swallowed  by  the  fault,  placing  the 
ore  at  5000'  beneath  III.— The  Short  Mountain  mine,  described  in  the  text 
above,  is  still  worked.  Yellow,  red  and  white  clays  in  heavy  masses,  many 
of  them  without  any  ore ;  ore  clays  apparently  in  three  stories,  with  barren 
clay  partings  :  (1)  upper  "sparry  ore  "  in  W.  wall  of  E.  large  open  pit;  (2) 
40'  and  (3)  60'  deep  in  W.  wall  rising  rapidly  to  the  surface  atvop  of  E.  wall. 
West  pit  60'  deep  now  abandoned.  See  analysis  of  ore  T,  239 ;  and  of  lime- 
stone flux  for  Etna  furnace,  in  which  is  C.  Mag.  3.9;  sulphur,  0.053;  phos- 
phorus, 0.011.  (T.  240.)— Dean's  bank,  250'xlO'  to  50'xlO'  to  15'  deep.  Small 
ore  in  wash  ;  at  E.  end  cut  abutted  squarely  against  solid  limestone  strata? 
mine  abandoned  ;  ore  very  red  short,  as  used  in  Williamsburg  furnace.  See 
analysis  T.  236.  — Patterson  mine,  on  the  Sandy  Central  ridge,  covered  with 
quantities  of  sharp  sand  ;  southern  shaft  80'  deep,  ore  struck  at  15'  and  left 
in  bottom  ;  ore  mass  worked  9'  thick  descending  vertically,  then  at  40'  depth 
bending  to  an  E.  dip ;  north  shaft  55'  deep,  ore  vertical,  taking  below  an  E. 
dip;  tunnel  ore  work  joins  the  two  ;  ore  of  two  kinds,  (1)  liver  ore,  often 


CANOE   VALLEY.  403 

It  is  significant  of  the  decline  of  the  Canoe  Valley  anti- 
clinal northwards  that  the  valley  narrows  and  the  bounding 
mountains  approach  each  other  closest  at  the  Little  Juni- 
ata.  It  follows  that  deeper  and  deeper  horizons  in  II 
reach  the  surface  successively  going  south  along  the  crest 
of  the  anticlinal,  which  makes  in  many  places  a  prominent 
central  ridge  on  which  are  ranged  the  principal  mines. 
Now,  as  we  encounter  on  the  map  going  south  no  mines 
until  after  passing  Water  street  and  Etna  furnace,  it  fol- 
lows that  the  upper  horizons  are  wanting,  and  that  all 
the  mines  are  on  horizons  from  2000'  to  5000'  beneath  III. 
Direct  cross  measurements  based  on  dips  verify  this  con- 
clusion, and  show  that  the  Etna  bank  is  something  less 
than  5000',  and  the  Springfield  bank  about  5000'  beneath 
III ;  while  the  other  side  banks  are  higher  in  the  series. 

The  Short  Mountain  mine  is  a  great  curiosity  for  those 
who  interest  themselves  with  geological  structure  ;  for  it 
is  situated  in  the  narrow  belt  of  the  slates  of  III  as  they 
swing  round  the  point  of  Short  Mountain  to  meet  Jackson' s 
fault.  But  neither  black  slate  nor  black  clay  is  to  be  seen 
in  the  extensive  open  cuts  (which  were  still  worked  a  lit- 
tle in  1876),  nor  any  limestone,  but  only  flints  and  sand  in 
abundance  in  the  ore-clays.  No  solid  rock  has  been  en- 
countered in  sinking  an  80'  shaft  and  driving  a  tunnel 
under  the  old  west  bank ;  nothing  but  white  sand  and 
sandy  clay ;  the  tunnel  entirely  in  white  sand  ;  yet  the 
shaft  is  just  south  of  the  south  end  of  the  large  open  mine. 
The  iron-coated  sandstone  rock  in  the  open  mine  dips  (ob- 
scurely) 46°,  N.  W.  The  bottom  of  the  ore  mass  has  never 
been  reached  and  great  quantities  remain  to  be  won.  The 
only  explanation  of  these  curious  facts  which  I  can  suggest 
is,  that  the  slate  belt  is  not  properly  located,  and  that  the 
mine  is  probably  on  the  line  of  Jackson's,  or  some  other 
(branch  ?)  fault,  like  the  Leathercracker  Cove  (Henrietta) 
mines  ;  but  the  ores  here  do  not  in  the  least  resemble  the 
Henrietta  ores.  On  the  contrary  all  the  circumstances 

silicious,  (2)  richer  deep  red  or  blackish  manganiferous  ore ;  output  not 
great.  See  analysis,  T,  235. — Red  ore  bank,  on  the  sandy  barrens  ;  northern 
pit  small ;  southern  open  cut,  40'  slope  ;  red  clay  holds  good  redshort  ore  ; 
much  flint  rock  through  clay  masses.  For  analyses  see  T,  233. 


404  GEOLOGICAL   SURVEY    OF   PENNSYLVANIA. 

here  suggest  the  Etna-Springfield  horizon,  only  that  there 
is  here  even  more  sand  and  less  clay  masses. 

The  red  short  qualities  of  some  of  the  No.  II  ores  is  ex- 
plained occasionally  by  the  presence  of  pyrites.  For  ex- 
ample, in  Dean's  ~barik,  a  shaft  15'  deep  in  the  floor  of  the 
open  cut  went  down  through  loose,  partly  decomposed  lime- 
stone and  extremely  sulphurous  iron  ore;  "in  fact,  there 
were  great  masses  of  decomposing  iron  pyrites,  with  a 
liematite  crust."  "  The  solid  rock  of  all  kinds  in  the  bank, 
whether  ore  pebbles  or  limestone  pieces,  are  all  rounded 
and  worn  smooth."  The  Cavern-deposit  nature  of  some  of 
these  ores  is  shown  in  the  Red  Ore  bank  where  shaft  No.  1, 
just  east  of  the  open  cut,  went  down  100'  through  sandy 
limestone,  although  the  ore  mass  was  plunging  directly 
towards  the  shaft ;  No.  2,  just  S.  of  the  mine,  went  60' 
through  limestone  ;  No.  3  and  4,  the  same.  The  deep  red 
clay  which  makes  such  a  show  at  the  surface  at  the  mine 
does  not  extend  beyond  it,  and  no  workable  surface  ores 
have  been  found  on  the  barrens  between  this  and  the 
Springfield  mine,  3  miles  further  south. 

The  Springfield  mines. 

These  rival  the  Pennsylvania  and  Bloomfield  mines. 
They  are  opened  on  the  high,  sandy,  barren  ridge  along  the 
center  of  Canoe  valley,*  Similes  south  of  the  Juniata  river 
at  Williamsburg,  1500'  A.  T.  A  section  of  the  valley  from 
Lock  (Canoe)  mountain  on  the  west,  across  to  Tussey 
mountain  on  the  east,  given  in  Fig.  13,  plate  XXIII,  will  il- 
lustrate the  low  horizon  of  the  ore  in  II,  say  5000'  beneath  III, 
the  mine  being  H  miles  from  the  bottom  edge  of  the  slate 
belt  (III)  with  dips  from  20°  to  70°  between. 

There  are  three  pits,  two  on- the  central  sand  ridge,  1500' 
apart,  and  one  in  the  lower  ground,  3000'  west  of  the  south- 
ern main  pit,  and  4000'  east  of  the  edge  of  the  slate  belt 
geologically.  Ore  pit,  No.  /,  is  about  4800'  beneath  III, 
but  being  on  W.  dips,  there  are  exposed  on  the  crown  of 

*Here  already  called  Morrison's  Cove,  although  it  opens  out  into  the  Cove 
some  miles  further  south. 


CANOE  VALLEY  ORE  BANKS. 


405 


£tna  and  ffprinqfield  T>anJcA. 


406  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

the  arch  to  the  east  of  it  strata  more  than  5600'  beneath  III. 
How  much  more  lie  concealed  in  the  arch  can  only  be 
guessed  by  the  little  Juniata  section,  which  measures  be- 
tween 6000'  and  TOGO'  feet  and  still  does  not  expose  the  bot- 
tom beds  of  the  great  formation. 

Mine  No.  1  (Dams  mine),  is  an  open  cut,  600'x500'x30' 
to  65'  deep.  It  is  surrounded  by  a  well  denned  ore  ground 
limit,  2600'  N.  and  S.  by  300'  to  1450'  wide,  outside  of  which 
the  surface  is  a  sandy  waste  without  ore,  as  both  surface 
show  and  trial  pits  combine  to  prove.  The  ores  are  of 
every  grade  of  color,  character  and  value.  Fig.  14  of  pi. 
XXII  shows  how  little  of  the  ore  mass  has  been  removed, 
chiefly  wash  ore.  Shafts  1,  2  and  3,  respectively  65',  100 
and  161'  deep,  show  the  depth  of  ore  mass,  as  they  strike 
the  sandstone  floor  on  which  the  ore  mass  lies  and  crops 
out  to  the  surface  on  theE.  side  of  the  mine,  disintegrating 
to  a  sharp  clean  sand.  The  upper  sandstone  layer  is 
heavily  incrusted  with  ore,  and  its  small  cavities  and  irreg- 
ularities are  filled  with  ore. 

The  first  60'  of  wash  ore  was  mined  in  open  cut ;  then  a 
60'  shaft  went  down  in  lump  and  wash  ore,  pitching  west 
against  the  sandstone.  The  wall  of  the  pit  must  be  ex- 
cessively steep  since  this  120'  shaft  is  only  35'  from  the  solid 
rock  wall.  The  mine  is  therefore  a  cavern  deposit,  one  of 
the  very  few  cases  wherein  a  demonstration  can  be  obtained.* 

Shaft  3  has  the  following  record  :  Loose  wash  ore  very 
lean  in  places,  clay  layers,  40'  ;  block  and  lump  ore,  2'  to 
3';  worthless  wash  sand  and  clay  masses,  112';  ore  in  white 
and  yellow  clay,  6';  sandstone,  massive  to  bottom  (161'). 
But  this  record  disagrees  with  every  other  section  in  the 
mine  and  may,  perhaps,  be  accounted  for  by  the  fact  that 
the  miners  were  in  search  of  large  lump  and  pipe  ore  only, 
and  considered  all  small- wash  ore-ground  worth  nothing  to 
them.  For  on  the  W.  side  of  the  bank,  wall  and  shaft 
prove  wash  ore  120'  deep.  Elsewhere  also  the  whole  mass 
is  solid  but  variable  wash  ore. 

It  is  interesting  that  loose  pieces  of  sandstone,  ferrugi- 

*It  is  possible  that  it  is  a  small  synclinal  on  the  crown  of  the  arch. 
(F.  Platt,  in  T,  162). 


THE   SPRINGFIELD   MINES.  407 

nous  slate,  and  pieces  of  sand  rock  greatly  resembling  spe- 
cimens of  IV  and  V.  and  conglomerated  sandstone  frag- 
ments held  fast  by  an  iron  ore  cement,  are  all  found  in  the 
ore  mass. 

Between  the  Davis  and  Lykens  pits,  say  2000',  is  barren 
ground. 

Mine  No.  2  (Lykens'),  is  600'x400'x80'  deep  (once  100') 
encircled  by  a  limit  of  ore  ground.  2200'xlOOO',  on  the  sur- 
face. It  is  worked  for  the  Cambria  Iron  Co.  The  Lykens' 
shaft  at  its  N.  end  has  a  great  output.  No  bottom  to  the 
ore  has  been  reached  in  the  cut  ;  but  the  shaft  strikes  the 
sand  rock  floor  at  215'.  It  works  solid  ore,  that  is,  great 
lumps  packed  close  together  in  the  clay  ;  usually  in  two 
layers,  the  upper  one  reddish  ore,  then  I/ to  4'  sand  or  sand- 
stone, then  the  lower  one  heavy  black  lump  ore  in  clay, 
resting  on  the  true  sandstone  floor.  Both  the  ore  layers 
and  the  sandstone  parting  vary  much  and  rapidly  in  thick- 
ness, but  in  the  main  rising  and  falling  together  conforma- 
bly to  the  irregularities  of  the  sandstone  floor.  This  mine 
is  remarkable  for  the  quantities  of  bombshell  ore  in  it,  and 
for  the  scarcity  of  honey  comb  ore.  The  bombs  are  some- 
times of  great  size,  some  filled  with  soft  white  lime  clay, 
others  with  more  or  less  decomposed  sandstone  or  sand, 
many  quite  hollow/* 

Mine  No.  3,  is  of  a  totally  different  character,  on  a  geo- 
logical horizon  only  2600'  beneath  III,  separated  by  more 
than  a  mile  of  barren  limestone  outcrops,  and  in  limestone 
hollows.  Its  wash  ore  body  contains  mostly  only  small 
rounded  water  worn  ore  balls. f  The  open  pit  6'  to  20'  deep 
shows  only  wash  ore  in  caves  in  the  limestone  separated  by 
promontories  and  ribs  of  limestone.  Fine  grained  waving 
purple  or  brown  or  white  clays  all  carry  varying  amounts 
of  the  ore  balls.  Dark  limestone  walls  in  the  whole  pit, 
and  an  occasional  layer  of  slate  parts  two  limestone  beds. 
The  floor  also  is  limestone. 

But  at  a  place  where  nearly  solid  ore  made  the  tempo- 

*See  other  details  and  numerous  ore  analyses  in  T,  163,  167. 
f  Occasionally  some  rounded  pieces  of  sandy  limestone  and  limestone  are 
noticed  in  this  mine  also. 


408  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

rary  floor  of  the  pit  a  horizontal  drift  followed  the  ore  (S. 
E.)  for  WO'  under  solid  limestone  cover,  and  soon  a  solid 
limestone  floor  was  got  also.  A  45'  shaft  from  the  surface 
struck  the  end  of  the  drift.  The  ore  layer,  thus  inclosed  in 
the  limestone,  when  mined  averaged  5',  but  varied  between 
V  and  19'.  This  is  very  remarkable  as  it  shows  the  possi- 
ble production  of  limonite  between  almost  horizontal  strata 
of  unchanged  rock.  It  also  shows  a  sort  of  broad  shallow 
synclinal,  (or  shelf  ?)  on  the  western  limb  of  the  Canoe  valley 
anticlinal. 

All  this  agrees  very  well  with  the  description  of  the  ore 
production  at  the  Pennsylvania  banks  in  Centre  county, 
which  are  also  on  the  same  geological  horizon,  viz :  2600' 
beneath  IIT.f 


The  Prussia  mine,  small,  abandoned,  1500'  S.  W.  of 
Springfield  No.  2.— Tar  Hole  bank  600'  N.  W.  of  the 
Prussia.—  McPheese  bank  3000'  S.  W.  of  Springfield  No. 
2,  but  separated  from  its  ore-area  by  barren  ground  ;  a 
small  pot  of  wash  ore. 


Canoe  valley,  at  Williamsburg,  and  at  Springfield,  is  4 
miles  wide, [measuring  between  the  two  edges  of  the  lime- 
stone floor,  and  5  between  the  crests  of  its  bounding 
mountains.  At  Rebecca  furnace  mines  (10  m.  S.  of  Wil- 
liamsburg its  width  is  but  3  miles.  Here  Canoe  (or  Lock) 
mountain  swings  round  to  the  west,  and  projects  as  a  broad 
round  synclinal  knob  southwards  into  Morrison's  Cove. 
The  slate  on  its  flank  runs  on  south,  in  the  synclinal  as 
a  narrow  belt,  past  Martinsburg  two  or  three  miles.  At 
Martinsburg  and  Fredericksburg  the  limestone  land  is  3  m. 
wide  ;  this  is  12  m.  S.  of  Williamsburg.  Millerstown  is 

\  See  further  description  and  numerous  analyses  in  T,  pp.  171  to  177.  No 
limonite  mines  are  more  extensive,  valuable,  or  better  worked  than  these 
and  that  is  my  excuse  for  so  largely  extracting  from  the  Report.  It  seems 
that  traces  of  cobalt  appear  also  in  these  ores,  T,  172,  173.  See  accounts  of 
plant,  machinery,  etc.,  T,  177. 


LEATHERCRACKER   COVE   ORES.  409 

14 ;  Henrietta  furnace  mines,  at  the  entrance  to  Leather- 
cracker  Cove,  15 ;  and  the  head  of  the  cove  17  m.  S.  of 
Williamsburg.  Between  Fredericksburg  and  Millerstown 
a  belt  of  slate  2£  m.  long  and  £  m.  wide  splits  the  lime- 
stone land  into  two  belts ;  the  eastern  one  lying  along 
the  foot  of  Tussey  running  S.  to  the  head  of  Leather- 
cracker  cove  ;  the  western  one  running  on  S.  past  Curry, 
Woodbury,  Waterside  and  Enterprise,  to  the  south  end 
of  Morrison's  cove.  The  slate  belt  is  a  sharp  and  faulted 
synclinal  between  the  Henrietta  (Leathercracker)  anticlinal 
and  the  Curry- Woodbury  anticlinal.* 

Leather  cracker  Cove  ores. 

The  Henrietta  mines  in  Leathercracker  Cove  have  been 
described  in  a  previous  chapter  on  the  Limonite  ores  of 
the  top  of  II,  but  only  in  such  general  terms  as  might 
state  their  possibly  very  exceptional  horizon  at  the  contact 
of  II-III.  This  was  once  considered  by  others  as  well  as 
by  myself  the  true  theory.  But  I  am  more  and  more 
confirmed  in  the  belief  that  this  is  a  mistake,  and  that 
they  belong  to  middle  horizons  of.  the  formation  brought 
by  the  faults  into  contact  with  III,  as  in  the  case  of  the 
Path  Valley  mines  in  Franklin  county. 

It  only  remains  to  notice  here  the  character  of  the  Hen- 
rietta ores,  referring  the  reader  to  Mr.  Platt's  full  details 
in  T,  183  to  202.  PL  XXIV,  f.  20  maps  the  main  pit, 
600'x200'x60'  deep,  all  in  ore  clay.  Projecting  boulders 
of  limestone,  much  rounded  by  chemical  decomposition, 
stand  up  irregularly  on  the  floor,  from  around  which  (as 
also  from  around  masses  of  barren  clay)  the  wash  ore  has 
been  removed,  f 

*On  the  great  map  sheets  of  the  Morrison's  Cove  Survey,  in  Atlas  to  T, 
this  is  improperly  named  the  Morrison's  Cove  anticlinal,  and  the  other  the 
Canoe  Valley  anticlinal.  In  fact,  however,  both  represent  the  great  Canoe 
Valley  anticlinal  in  its  southern  course  where  its  crest  is  split  by  a  synclinal 
roll.  The  Bloomfield  anticlinal  is  a  great  wave  of  the  western  half  of  Mor- 
rison's Cove.  The  Woodbury-Curry  half  of  the  Canoe  Valley  anticlinal 
becomes  the  great  wave  of  the  eastern  half  of  Morrison's  Cove  ;  the  two  be- 
ing separated  only  by  the  wide  shallow  synclinal  of  Lock  Mountain. 

f  Some  of  the  main  features  of  the  mine  are  similar  to  features  found  in 
nearly  all  the  brown  hematite  deposits  of  the  lower  Siluro-cambrian  lime- 


410  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 


and  <&eatnerc>racfce<r  Core 


a£  Rebecca  and  XCenriettu.  furnttcet  . 


HENRIETTA    FURNACE    BANKS.  411 

Always  on  the  E.  side  of  the  pit  is  the  black  clay  which 
ovej'lies  the  ore  mass  /*  always  on  the  W.  side  the  under- 
lying limestone  clay  /  solid  limestone  W.  of  the  mine, 
dipping  nowhere  more  than  30°,  S.  70°  E.  But  the  slope 
of  the  ore  from  crop  to  bottom  is  much  steeper;  but  the 
pot  which  holds  the  ore  is  evidently  not  shaped  by  the 
limestone  dip,  but  is  excavated  in  the  limestone,  the  un- 

stones.  At  times  the  ore  runs  in  great  masses,  packed  together  and  like  a 
regular  ore  bed  ;  and  this  fades  out  more  or  less  gradually,  plainly  in  sight, 
into  a  clay,  carrying  perhaps  not  so  much  as  10  per  cent,  of  ore  in  it.  The 
streaks  of  clay  follow  no  dip  ;  they  are  tolded  and  rolled  in  all  shapes  ;  conie 
in  suddenly  and  as  suddenly  entirely  disappear;  are  in  places  white  and 
perfectly  free  either  from  ferruginous  coloring  matter,  or  from  wash  ore ; 
and  are  again  deep  red  or  brown,  and  sticky. 

"But  the  mine  differs  from  many,  in  fact  from  most,  ore  banks  of  Morri- 
son's Cove,  in  that  it  shows  no  sand,  no  sandstone,  no  flint,  and  no  rock  of 
any  kind  but  blue  limestone.  But  in  place  of  rock  and  flint  some  of  the 
clay  layers  are  unusually  sticky,  and  form  balls  which  pass  through  the 
washer  with  the  ore,  and  give  quite  as  much  trouble  as  flint  in  requiring  to 
be  picked  by  hand. 

"There  is  much  iron  ore  in  mine  No.  1,  which  carries  varying  and  some- 
times very  considerable  percentages  of  manganese.  These  patches  of  man- 
ganiferous  iron  ore  are  very  local  and  very  irregular  in  shape.  There  is  no 
guide  to  say  when  to  expect  them,  or  to  indicate  when  they  will  run  into 
the  ordinary  brown  hematite  ore.  The  manganiferous  ore  chiefly  showed 
at  a  depth  of  about  50  feet  below  the  surface  ;  and  there  are  now  large  quan- 
tities in  the  present  bottom  of  the  pit.  The  tendency  to  run  to  manganifer 
ous  iron  ore  is  (at  the  present  depth)  much  the  strongest  at  the  south  end 
of  the  mine. 

"  The  ore  is  usually  hard  and  darker  colored  in  the  upper  part  of  the  de- 
posit, or  that  nearer  to  the  black  slates,  while  it  is  apt  to  be  softer  and  more 
open  in  the  lower  part,  in  the  limestone.  But  while  this  distinction  may 
hold  roughly,  yet  all  kinds  of  ore,  hard,  soft,  manganiferous,  rich  and  lean, 
may  be  found  close  together,  and  in  fact  mixed  together  in  the  same  clay 
bands."  (Platt,  T,  186.) 

*"The  overlying  non-ore-bearing  dark-colored  slates  are  much  weathered 
down,  almost  to  a  mud,  to  which  condition  indeed  they  soon  come  on  ex- 
posure. When  first  exposed  they  show  as  very  thin-bedded,  fragile,  black 
slates,  fossiliferous  in  places,  though  the  fossils  are  kept  with  difficulty  on 
account  of  the  fragility  of  the  whole  material.  Fifteen  feet  of  this  black 
slate  rest  on  top  of  the  iron  ore  and  clay  ;  and  on  top  of  that  there  apparently 
commences  a  gray  colored,  soft,  iron-stained,  thin-bedded  clay-slate,  non- 
fossiliferous  so  far  as  seen.  These  slates  and  the  surface  stuff  make  a  loose 
and  somewhat  troublesome  east  wall  for  the  mine;  the  clays  holding  back 
the  water  and  throwing  it  over  the  top,  the  effect  being  to  make  the  washing 
down  so  severe  as  to  require  almost  foot  for  foot  as  a  safe  slope  tor  the  east 
wall."  (F.  Platt,  T,  190.) 


412  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

equal  dissolution  of  which  waves  the   ore-mass  backward 
and  forward  with  gentler  and  steeper  slopes  alternately.* 

Total  excavation  270,000  cubic  yards  ;  total  of  ore  realized 
64,000  tons,  or  16  per  cent,  of  the  stuff  excavated.  All 
goes  to  the  Cambria  Iron  Works  at  Johnstown. 

The  Faulkner  shaft,  1200'  S.  of  main  pit  ;  mouth  40' 
higher  than  surface  at  main  pit ;  depth  of  shaft  153',  with 
ore  left  in  bottom  ;  ore  struck  first  40'  down  ;  output  10,000 
tons  ;  abandoned.  Three  monkey  drifts  found  the  descend- 
ing ore  mass  to  be  25',  25',  and  40'  from  wall  to  wall.  Drift 
S.  from  bottom  of  shaft,  400'  to  500',  showed  the  curious 
structure  of  Fig.  22.  f 

The  McAUster  shaft,  2700'  S.  of  Faulkner  shaft,  still 
following  line  of  fault ;  100'  deep  ;  black  clay  hanging  wall  ; 
limestone  clay  foot  wall  ;  ore  clay  15'  to  20'  thick,  vertical, 
irregular. 

The  Hoover  mine,  750'  S.  of  McAllister  shaft ;  open  cut 
200'xl25'x30'  deep  ;  shaft,  120',  struck  some  ore  near  bot- 
tom ;  black  clay  in  E.  wall  of  open  cut ;  W.  wall  lime  clay, 
and  back  of  it  limestone  ;  %  ore  clay  15'  to  20'  thick,  unusu- 
ally sticky  and  troublesome. 

This  Henrietta  ore  range  is  a  well  denned,  limited  and 
local  deposit  of  ore  clays  in  a  fault-trench  7000'  long,  15 
to  35'  wide  and  of  unknown  depths,  between  a  wall  of 
black  (Utica  ?  or  Hudson  river.  Ill)  slate,  on  the  one  side, 
and  a  wall  of  dolomite  strata  belonging  to  some  unknown, 
probably  middle  horizon  of  Chazy  or  Calciferous  formation 
II ;  both  walls  thoroughly  decomposed  into  black  and  white 
clays  ;  without  the  intervention  of  any  igneous  rock  like 
trap  as  at  Cornwall,  but,  perhaps,  by  the  hot  waters  from 
a  great  depth,  as  at  the  Hot  and  Warm  Springs  along  the 

*The  analysis  of  limestones  given  in  T,  p.  1888,  show  that  they  are  almost 
perfect  dolomites  (53  :  35  and  57  :  39. 

fThe  ore  clay  forked,  one  part  going  straight  on,  the  other  curving 
round,  carrying  rich  ore  all  the  way  until  it  rejoined  the  other  ;  black  clay 
horse  (without  ore)  Jfl'  wide. — Black  clay  is  the  hanging  wall  and  limestone 
clay  the  foot  wall  in  all  the  Faulkner  shaft  workings  without  exception. 
Ore  dark  and  hard,  especially  towards  the  hanging  wall ;  foot  ore  more  cel- 
lular. See  analysis  T,  192.  fhosphorus  too  high,  0.940. 

J  Also  here  a  dolomite  (46:40)  which  of  itself  precludes  the  theory  of  this 
ore  being  made  out  of  damourite  slates  at  the  contact  of  II  and  III  (T,  196). 


LEATHKRCRACKER   COVE   ORES.  413 

great  fault  in  Virginia.  But  it  is  not  at  all  necessary  to 
suppose  the  water  hot  or  even  warm  ;  for  the  process  was 
evidently  the  same  at  the  other  limonite  mines  of  this  region 
where  no  faults  exist.  The  ordinary  solvent  powers  of  the 
rainfall  are  quite  capable  of  carrying  on  the  operation, 
which  in  fact  it  is  doing  all  the  time  at  the  present  day. — 
Nor  is  a  cavern  deposit  here  in  question  ;  for  the  ore  mass 
here  is  not  made  up  of  rounded  pebbles  ;  nor  can  any  other 
water  worn  detritus  be  seen  in  these  mines.* 

The  Leathercracker  (Henrietta)  ores  are  too  phosphatic 
for  the  Bessemer  process.  Three  analyses  of  samples  from 
the  three  Cambria  Co.'s  mines,  show  :  Sesq.  ox.  iron,  60, 
63.6,  69.4;  Sesq.  ox.  mang.,  3.5,  1,  0.3;  phos.  acid,  0.822, 
2.153,  1.021,  etc.  (T,  197).  But  they  are  high  in  iron, 
cheaply  mined,  and  kind  in  the  furnace  ;  were  in  great  de- 
mand for  stock  mixtures  so  long  as  iron  rails  ruled  the 
market ;  but  have  declined  in  value  in  this  new  age  of  steel 
rails.  Thomas  and  Grilchrisfs  basis  process  may,  perhaps, 
restore  their  old  value. 

The  Schoolhouse  mine  on  the  W.  side  of  Leathercracker 
cove,  on  the  other  fault  line,  is  described  in  T,  199.  See 
Fig.  22a. 

The  Bolster  mine  of  "neutral  ore,"  3£  m.  N.  of  Wood- 
bury  ;  two  open  pits,  separated  by  the  road,  100'x60'x20', 
long  abandoned  and  a  smaller  pit ;  ore  rich,  very  sulphur- 
ous ;  great  masses  of  decomposing  pyrites  ;  unusually  red 
clays  ;  no  water  ;  no  solid  rock  ;  ore  lumps  not  rounded  ; 
many  rounded  flints  and  limestones  ;  geological  horizon 
about  2500'  beneath  III,  that  of  the  Pennsylvania  furnace 
mine  in  Centre  county. 

*"The  ore  is  in  lumps  of  all  sizes,  ranging  from  large  and  heavy  masses 
closely  packed  together  until  they  resemble  a  bed  of  ore,  to  fine  grains  thinly 
disseminated  through  various  colored  clays.  But  all  the  ore  pieces  are  ir- 
regular in  shape  and  with  points  and  angles,  sharp  on  the  corners,  and  in 
many  cases  coated  with  little  needles  of  ore,  which  the  smallest  friction 
would  soon  rub  oft'.  This  is  the  unvarying  character  of  the  structure  of  the 
ore  lumps  and  grains  in  Leathercracker  Cove."  (Platt,  T.  197.) 


414  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

Morrison  Cove  ores. 

The  Bloomfield  mine  on  Duncan's  ridge,  3  m.  S.  of 
Hearing  spring  (where  its  branch  railroad  joins  the  line 
from  Henrietta  mines  to  Hollidaysburg)  is  famous  for  furn- 
ishing stock  to  Bloomfield,  Sarah,  Martha  and  Rebecca 
furnaces,  making  the  best  gun  metal  for  theU.  S.  foundry 
at.  Pittsburgh. 

Halter's  creek  flows  between  Duncan's  ridge  and  Dun- 
ning's  mountain.  The  Lock  mountain  anticlinal  of  Mor- 
rison's cove  runs  E.  of  the  mines  ;  very  gentle  E.  dips  into 
the  Martinsburg  shallow  and  broad  synclinal ;  overturned 
steep  E.  dips  (instead  of  normal  W.  dips)  at  the  mines  and 
in  Halter's  valley  and  in  Dunning  mountain.  A  slip  fault 
is  probable  but  not  demonstrated.  Depth  of  ore  horizon 
beneath  III,  (calculated)  3200';  therefore  700'  lower  down 
than  the  horizon  of  Pennsylvania  and  1800'  higher  up  than 
the  Springfield  ore  horizon.* 

The  reader  will  find  a  fully  detailed  description  of  the  mine 
in  Mr.  F.  Platt's  Report  on  Blair  county  T,  1881,  p.  203  to 
221.  All  along  the  valley  between  Duncan's  ridge  and 
Dunning  mountain  runs  a  belt  of  ore  clays,  from  1  m.  N.  of 
Roaring  spring  southward  past  the  Bloomfield  school  house, 
Bakersville  ore  pit,  Long's,  to  the  Stukely  farm,  a  distance 
of  7  or  8  miles  ;  in  some  places  slight,  in  others  heavy,  but 
none  but  that  at  Bakersville  promising  a  great  yield. 

The  Bloomfield  ore  clays  are  continuous  for  7200',  from 
the  N".  end  of  the  German  bank  to  the  S.  end  of  the 
Clarke  banks,  with  a  width  of  1000'  to  1500,  across 
the  top  of  Duncans  ridge. f  The  larger  clay  masses  are 
more  than  100'  deep.  The  ore  ground  ends  abruptly 

*  I  have  placed  the  cross-section  showing  mine,  anticlinal,  etc.,  on  the 
Bloomfleld  mine  map,  plate  XXV,  page  415.  The  Loop  mountain  anti- 
clinal is  described  in  T,  p.  63,  etc. ;  the  mine  in  T,  p.  203,  etc.  Dunning's 
mountain  has  a  strike  of  N.  22°  E.  but  the  anticlinal  axis  runs  nearly  due 
N.  into  the  Loop,  and  through  to  Frankstown. 

f  The  map  shows  where  the  greatest  output  has  been  made,  but  many 
trial  shafts  found  nothing  but  very  lean  sand  and  clay.  The  water  shaft  and 
boring,  225' deep,  went  all  the  way  through  sand  and  clay,  with  no  solid 
rock  beds,  and  no  water,  and  ended  in  sharp  sand.  Trial  pits  just  north  of 
German  bank  went  through  solid  rock  without  ore. 


MORRISON'S  COVE  ORES. 


415 


r\  \  \\ 

ny.z4. 
Section  from  DunnuigsAElJiroaghBloomfieldMfms. 


416  GEOLOGICAL   SURVEY    OF   PENNSYLVANIA. 

northward  at  the  German  bank.  So  also  south  of 
the  Clark  bank  solid  limestone  is  at  the  surface.  But  in 
the  mines  no  limestone  ribs  are  seen  and  none  were  struck 
in  intermediate  trial  shafts  and  borings.  It  looks  as  if  the 
ore  mass  were  the  filling  of  a  vast  cavern,  which  has  lost 
its  roof.  In  spite  of  the  long  time  working  of  the  mine, 
only  a  portion  of  its  wealth  has  been  extracted.* 

The  mine  shows  the  usual  great  and  sudden  changes  in 
the  character  of  the  ore  bearing  mass  ;  a  iion-ore-bearing 
clay  will  suddenly  change  into  a  rich  wash  ore  deposit, 

*  The  Main  bank,  including  the  German,  is  1800'x  100'  to  400'  x80'  deep.  In 
1880  it  was  beingworked  with  renewed  vigor  (See  T,  p.  205).— The  Harrity 
open  cut  is  350'  long.  Its  clays  are  beautifully  stratified,  dipping  10°,  E. 
"white  clay  caps  the  ore-bearing  clays  with  the  same  dip,  and  requires  25'  of 
stripping.  Over  the  -white  clay  ore-clays  are  worked  for  200'  along  the 
strike  (N.  and  S. ).  This  same  white  clay  is  struck  in  shafts  N.  and  S.  of  the 
bank.  No  better  evidence  of  change  of  rock  in  situ  could  be  got ;  and  yet 
the  sudden  N.  and  S.  termination  of  the  field  does  not  look  like  it ;  unless  a 
change  in  a  character  of  the  anticlinal  is  taken  into  consideration.  Some  of 
the  clays  are  blood-red  ;  occasionally  they  hold  manganese,  as,  for  example  in 
shaft  500'  S.  of  main  bank,  from  which  manganese  ore  was  shipped  for 
spiegeleisen.  Usually  these  shafts  brought  up  manganese  ore  that  was  too 
sandy  for  use. — The  New  Wash  Machine  bank.  Here  2'  of  sand  makes  a  layer 
between  ore-bearing  clays,  and  as  regular  as  a  sandstone  bed.  The  Sand 
bank  in  a  sandy  barren  surface  soil,  has  15'  siliceous  ore  in  sandy  clay,  15'; 
underneath  which  yellow  and  brown  clays  holding  not  much  ore ;  then 
brown  clay  holding  excellent  mang aniferous  limonite  masses  packed 
in  the  clay  so  as  to  warrant  the  miners  in  calling  it  a  4'  bed.  —  TheRidgt 
banks  are  numerous  pits  S.  of  the  Sand  bank  ;  the  main  one  large  ;  ore  out- 
crop heavy;  sand  and  flint  on  the  surface  but  very  little  in  the  bank  itself  ; 
good  ore  in  yellow  clay  goes  deep  ;  shafts  60';  lump  masses  closely  packed 
in  clay  still  in  bottom  ;  miners  merely  followed  these  lump  streaks.  In  a 
new  pit  white  clay  has  many  scattered  quartz  crystals  in  it. —  The  Krofft 
banks  are  further  south. —  The  Clarke  banks  come  next;  ore  mass  solid  4 
to  9'  at  40'  beneath  surface  ;  in  S.  Clarke  bank  another  at  100'  deep.  (T,  211.) 
If  the  surface  lean  silicious  stuff  15'  to  20'  deep  were  stripped,  systematic 
mining  here  would  yield  an  enormous  quantity  of  good  ore. — The  Old 
Barley  bank,  \^  m.  S.  of  Clarke  bank,  abandoned.—  Stuckey  and  Leidig 
banks,  2^  m.  further  S.  shallow  and  hopeful.  The  Bloomfield  plant,  ma- 
chinery, washing  and  method  of  working  the  mine,  are  all  described  in  T, 
pp.  212  to  214.  For  numerous  analyses  of  the  ore  (as  received  at  the  fur- 
naces) by  McCreath,  Wuth,  and  Salom,  seeT,  pp.  214  to  219.  The  Rodman 
Furnace  "gun  metal"  pig,  made  in  1872,  1874,  showed  :  Silicon  4.004,  3.184, 
2.713;  Sulphvr,  0.035,  0.082,  0.123  ;  Phosphorus,  0.195,  0.195,  0.192  ;  Mangan- 
ese, 0.144,  0.864.  It  was  used  in  the  Bessemer  flasks  of  the  Pa.  Steel  Co.  at 
Baldwin.  Captain  Rodman,  U.  S.  A.,  urged  the  U.  S.  Government  to  secure 
by  purchase  the  whole  Bloomfield  ore  field.  (T,  229.) 


MORRISON'S  COVE  MINES.  417 

and  vice  versa  ;  while  masses  of  sandstone,  coated  with 
oxide  of  iron,  or  flint  pieces  large  and  small  come  into 
the  ore  mass  and  leave  it  without  any  visible  law.  Some- 
times there  are  huge  walls  of  tough  sticky  clay  in  sight 
bearing  no  iron  ore  ;  and  again  almost  everything  is  wash- 
able. The  mine  therefore  does  not  differ  from  the  other 
ore  deposits  of  Morrison's  cove  in  the  character  of  its  de- 
posit, but  only  in  the  unusually  enormous  quantities  of 
iron  ore  in  sight  and  in  their  freedom  from  phosphoric 
acid"  Consequently  the  Cambria  Iron  Works  at  Johns- 
town was  taking  (March,  1879)  all  the  jigged  Bloomfield  ore 
although  they  called  it  only  a  39  per  cent.  ore.  Phosphorus 
is  not  wholly  absent  from  any  of  the  analyses,  and  traces 
of  both  cobalt  and  nickel  appear  in  some  of  them.  Sul- 
phur is  usually  present  in  small  quantities,  but  in  some  is 
quite  absent. 

It  is  noteworthy  that  both  sulphur  and  phosphorus  ap- 
pear in  all  three  of  the  Rodman  furnace  limestone  flux 
analyses  given  in  the  Report  (T,  218)  thus : — Garb,  lime, 
78.2,  91.9,  54.6;  carb.  magnesia,  10.7,  2.9,  44.2;  ox.  iron 
and  al.,  1.8,  0.6,0.2;  Sulphur,  0.149,  0.096,  0.002;  phos- 
phorus, 0.029,  0.022,  0.003  ;  insol.  residue,  8.6,  4.4,  1.3. 

Other  mines  in  Morrison's  Cove. 

The  Baker  smile  mine,  2  m.  S.  W.  of  the  Bloomfield  mine, 
is  in  the  valley  W.  of  Duncan's  ridge,  and  therefore  on 
geologically  higher  outcrops,  but  in  a  heavy  surface  wash 
ore  deposit  1500'  N.  and  S.  by  400'  E.  and  W.  No  solid 
rock  in  place  has  been  struck  by  any  of  the  trial  shafts  75' 
deep.  The  deep,  narrow  valley  has  probably  once  been  an 
immense  cavern,  like  Sinking  Creek  cavern  in  the  northern 
part  of  Blair  county.  The  open  cut  is  300'x45'xl5',  in  sand 
and  sandy  clay,  yellowish,  sometimes  reddish,  holding  ore 
balls  from  top  to  bottom  ;  not  a  single  piece  of  loose  lime- 
stone ever  found ;  many  large  pieces  of  sandstone,  coated 
with  an  iron  crust,  not  rounded  and  worn  (as  a  rule),  nor 
are  the  rounded  ore  chunks  ;  nor  do  they  follow  any  line, 
nor  make  layers,  but  are  scattered  through  the  whole  sand- 
27 


418  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

clay  mass  ;  ore,  of  all  varieties,  water- worn  rich  dark  lumps, 
porous  honeycomb  ore,  dark  red  solid  somewhat  sandy 
ore,  light  brown  lean  sandy  ore,  and  light  brown  rich  ore. 
(T,  220.) 

The  Miller -stown  Red  Ore  bank,  1£  m.  N.  E.  of  the  vil- 
lage, large,  shallow,  long-abandoned  ;  wash  ore,  in  which 
knobs  and  masses  of  undissolved  limestone  make  an  irregu- 
lar floor ;  clay  deep  red  ;  ore,  limestone  and  flint  pieces  gen- 
erally if  not  always  rounded  and  water-worn,  usually  small, 
never  in  large  masses ;  shafts  reported  100'  deep  in  ore  to 
bottom.  Belt  of  red  clay  surface  extends  several  miles  N. 
&  S.  but  no  trial  pits  have  ever  found  ore  except  at  this 
one  spot,  the  size  of  the  mine  ;  evidently  a  cavern  deposit. 
Analysis  by  McCreath :  Iron,  54 ;  manganese,  0.065  ;  sul- 
phur, 0.017;  phosphorus,  0.085. — Calculated  ore  horizon 
only  1100'  beneath  III. 

The  Rebecca  ore  mines,  3  m.  N.  70°  E.  of  Martinsburg, 
were  worked  for  60  years  for  Rebecca  furnace.*  An  open 
cut  80()/xl25'  to  300/x70/  and  more  (now  only  50')  parallel  to 
to  Tussey  mountain  ;  W.  and  N.  walls  solid  non-ore-bear- 
ing white  clay  dipping  (apparently)  70°,  E.  S.  E.  oner  which 
clays  holding  masses  of  bombshell  ("copper  shell")  ore, 
lean,  brown,  sandy,  worthless  (because  only  15  per  cent, 
iron  and  stained  with  copper  oxide).  Worked  4  years  by 
shafts,  as  shown  in  section,  plate  XXIV,  fig.  27.  f 

The  Thompson  mine,  I  m.  S.  of  Martinsburg  ;  shallow 
holes  furnishing  cellular,  fibrous  and  sometimes  pipe  ore  ; 
many  honeycombed  ;  somewhat  red-short.  Horizon  (cal- 
culated} about  2500'  beneatJi  III,  i.  e.,  about  the  horizon  of 
the  Pennsylvania  bank  in  Centre  county. 

*  Described  in  T,  223  ;  surveyed  in  1877.  See  map  and  section  of  it  in  Fig. 
27,  28,  plate  XXIV.  Worked  continuously  lor  Rebecca  from  1817  onwards ; 
consequently  a  very  large  output. 

f  Barren  white  clay  80'  deep  at  top  of  main  shaft  (i.  e.,  50'  or  60'  thick) 
ore  clay,  50' ;  ore  mass,  15'.  East  shaft  found  only  white  sand  and  no  ore. 
The  ore  is  not  in  water  worn  or  rounded  pieces,  but  in  irregular  masses  and 
chunks,  sharp  pointed,  surrounded  by  clay.  Ore  has  always  made  a  first- 
class  metal ;  much  of  the  war  gun  metal  was  made  from  it. 


VALLEYS   AND   COVES   OF   NO.  II.  419 


CHAPTER  XXXV. 

Other  anticlinal  limestone  valleys  and  coves  hi  the  middle 
counties:  Friends  cove;  Mllligen"  s  cove  ;  Kishicoquillis 
valley  ;  Blade  Log  valley ;  McConnellsburg  cove  ;  Horse 
valley. 

Friends  cove. 

Friends  Cove  in  Bedford  county  is  connected  with  the 
southern  end  of  Morrison's  Cove  by  a  narrow,  anticlinal 
strip  of  slate  No.  Ill  between  Dunning  (Evitts)  and  Tussey 
mountains*.  Itslimestone  floor  is  15  miles  long,  by  3  miles 
wide;  ending  northward  in  a  point  4£  m.  N.  E.  of  Willow 
Grove;  and  southward  in  two  points,  at  Rainsburg,  a  village 
on  the  contact  of  Utica  slate  (Ilia)  and  Trenton  limestone 
(lie).  The  lower  Medina  sandstone  (TVa)  makes  a  terrace 
all  round  the  Cove,  as  in  Morrison's  Cove  and  Nittany  Val- 
ley. The  limestone  rocks  at  Rainsburg  dip  20°,  *S.  55°  E. 
At  Chaiiesville  near  the  N.  W.  side  of  the  Cove,  a  local  8°, 
S.  55°  W.  dip  shows  that  the  formation  is  disturbed.  The 
Cove  is  divided  by  a  middle  ridge  of  very  sandy  limestones, 
which  proves  the  general  steep  dips  by  bringing  up  the 
lower  portions  of  the  formation  ;  and  the  sand  eroded  from 
these  outcrops  covers  the  surface  of  the  Cove  to  a  great  ex- 
tent, concealing  the  outcrops,  and  any  deposits  of  limonite 
ore  which  they  may  hold.  Occasionally  a  piece  of  ore  may 
be  picked  up.  Cove  creek  flows  along  the  S.  E.  edge  of  the 
limestone;  has  a  broad  bottom  reaching  to  the  foot  of  Tussey 
mountain;  and  shows  no  exposures,  only  here  and  there  a 
little  water-worn  limestone;  but  is  covered  with  bowlders 
of  limestone  and  sandstone  from  the  mountain.  Some  lim- 
onite was  seen  by  Prof.  Stevenson  on  WeisePs  farm  1  m. 
S.  of  Koons'  mill.f 

*  See  Geol.  Atlas  of  Counties,  Report  X,  1885,  Map  No.  5,  preface  descrip- 
tion, p.  24. 

f  A  specimen  from  Koons'  quarry  gave  carb.  lime,  90.6;  carb.  mag.,  1.9. 
ox.  iron  and  alumina,  0.6;  sulphur,  0.02;  phosphorus;  0.005;  insol.,  6.41.  Mc- 
Creath  in  T2,  163.  Of  course  the  quarry  is  in  Trenton  lie. 


420  GEOLOGICAL   SURVEY   OF    PENNSYLVANIA. 

Much  chert  occurs  on  the  central  ridge  in  irregular  frag- 
ments, with  here  and  there  abed  of  limonite  ore,  evidently 
little  of  it.  On  L.  Whetstone' s  farm  ore  is  said  to  be  plenty  ; 
cindery  chert  is  abundant ;  and  the  sandy  soil  is  full  of 
Medina  sandstone  fragments,  and  also  pieces  of  Hudson 
river  slate.  On  the  adjoining  Diehl  place  and  in  A.  Whet- 
stone's fences  there  are  plenty  of  pieces  of  ore. 

Between  this  and  the  Juniata  river  many  exposures  of 
limestone  show  dips  of  27°  to  35°,  S.  85°  to  40°  E.  and  lime 
is  burned  for  manure.*  The  road  along  the  S.  side  of  the 
river  has  plenty  of  limestone  exposures  ;  and  shows  a  good 
deal  of  ore  where  it  crosses  the  middle  barren  sandy  ridge. 
From  the  railroad  cuttings  Prof.  Stevenson  obtained  the 
following  section. 

Limestone  (45°  E.)  dark  above,  lighter  below  ;  some  beds 
magnesian  ;  very  little  chert  ;  fossils  few  (S.  alt.,  Lep.  ser. 
Gal.  sen.}  ;  430';  Limestone,  (40°  E.)  light  grey  to  blue 
above,  growing  silicious  and  cherty  downwards,  until  at  the 
bottom  the  chert  makes  £  the  mass;  1350'  :  Concealed,  420'; 
Limestone,  (dip  45°  E.)  420' ;  Concealed,  400'  ? ;  Limestone, 
silicious,  175';  Concealed,  150';  Limestone,  very  cherty, 
300';  Concealed,  90';  Limestone,  sandy,  with  very  little 
chert ;  a  true  Calciferous  sandstone,  175'; — total,  4520'  of 
measures  not  reaching  the  bottom  of  No,  II.  f 

Milligeri s  cone.% 

Milligerts  Cove  in  Bedford  county,  is  about  10  miles  long 
and  a  mile  wide,  very  long  and  narrow,  floored  with  Hudson 
river  slate  (UK),  except  at  one  spot  in  its  center,  where 
the  sharp  anticlinal  brings  up  the  upper  beds  of  Tren- 
ton limestone  (He).  The  Utica  slates  (Ilia)  are  exposed  at 
Miller's  dipping  35°,  S.  35°  E.  near  the  exposure  of  Trenton 
limestone.  Of  course  there  are  no  limonite  mines  in  this 
cove4 

*  Trenton  limestone,  holding  the  fossils  Strophomena  alternata  and  Caly- 
nene  senana  (T2,  p.  163). 

f  Stevenson's  Report  T2,  pp.  93,  164. 

jStevenson's  Report  T2,  p.  108. 

§Also  spelled  Millikin's  and  Milligan's 


VALLEYS   AND   COVES   OF   NO.  II.  421 

KisMcoquillis  valley. 

Kishicoquillis  Valley,  making  the  N.  W.  half  of  Mifflin 
county,  is  a  beautiful,  fertile  valley,  secluded  between  Jack's 
mountain  and  Standing  Stone  mountain.  At  its  eastern  end 
it  is  split  by  two  long  promontories  into  three  narrow  par- 
allel vales,  each  of  which  has  an  anticlinal  floor  of  the 
slates  of  III.  The  limestone  floor  of  the  valley  itself  is  about 
27  miles  long  by  2£  wide  opposite  Reedsville  and  Milroy,  2  at 
Belleville  and  Menno,  and  1£  at  Allenville  near  the  Hunting- 
don county  line.* 

Two  anticlinal  waves  lift  the  valley  limestones  ;  a  third 
passes  behind  Milroy.  The  Greenwood  fault  cuts  obliquely 
through  Stone  mountain,  N.  of  Belleville,  and  throws  the 
terrace  of  IVa  against  the  mountain  of  IVc.  f 

The  limestone  beds  along  the  center  belt  of  the  valley  lie 
remarkably  flat,  so  that  erosion  has  not  yet  gone  deep  into 
the  formation.  In  Logan  Gap,  through  which  Kishico- 
quillis  creek  escapes  from  the  valley  to  join  the  Juniata 
near  Lewistown,  there  is  a  well  exposed  section  of  S.  E. 
dipping  Medina  and  Oneida  strata  (IV)  measuring  2,722 
feet.  Under  these  lie  Hudson  river  slate  and  sandstone  in 
four  divisions,  425',  190',  140',  182';  and  Utica  shale  in  three 
divisions,  210',  302';  855' ;  making  III  in  all  2304'  thick. 
Under  these  are  exposed  only  320'  of  Trenton  limestone  at 
the  surface. 

The  Greenwood  ore  banks  were  excavated  on  the  anticlinal 
axis  south  of  Belleville.  At  Belleville  are  dips  of  15°  to 
20°,  N.  W.  and  10°  near  the  mine.  Much  pipe  ore  was  got 
here  and  carried  across  Stone  mountain  to  the  furnace  to 
mix  with  fossil  ore  there  mined.  But  the  bank  was  aban- 
doned many  years  ago,  partly  on  account  of  the  cost,  and 
partly  from  lack  of  ore,  wrhich  was  only  found  in  pots  and 
pockets  in  the  limestone.  Many  such  pockets  were  ex- 
ploited in  early  times  in  other  parts  of  the  valley;  but  all 

*See  Geol.  Atlas  of  counties,  Report  X,  188?>,  p.  77,  and  the  map  of  Miftiin 
county  in  the  same  Atlas,  No.  41. 

t  DescribecTin  detail  and  with  special  maps  in  Report  T3.  The  valley  is  de- 
scribed hy  d'Invilliers  in  his  report  F3  and  the  fault  on  p.  239.  It  will  be 
hereafter  described  in  the  chapter  on  Oneida  and  Medina  sandstone  forma- 
tion N.  IV. 


422  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

mining  was  long  ago  abandoned.  No  doubt  there  is  this 
good  geological  reason  for  a  scarcity  of  ore,  viz:  that  the 
valley  erosion  had  not  been  carried  down  deep  enough  into 
the  magnesian  (Chazy)  part  of  the  formation.* 

The  fact  is,  the  Trenton  is  so  thick  and  the  dips  are  usu- 
ally so  low,  that  the  Chazy  has  but  little  chance  to  reach 
the  present  surface.  On  the  other  hand  the  limestone 
quarries  of  the  valley  are  all  excellent,  and  the  Trenton 
beds  furnish  also  hydraulic  limestone,  on  which  at  Milroy 
a  large  plant  is  now  (1891)  being  established,  f 

Black  Log  valley. 

Slack  Log  valley  in  Huntingdon  county  (its  N.  E. 
end  in  Mifflin)  is  20  miles  long,  by  1  mile  wide,  and  on  a 
gentle  curve4  It  is  a  fine  specimen  of  the  class  of  valleys 
and  coves  of  limestone  and  slate  produced  by  the  erosion 
of  the  high  steep  compressed  rock  waves  of  Pennsylvania. 
In  this  case  the  anticlinal  had  a  double  crest,  which  it 
shows  at  the  present  surface ;  but  it  is  probably  a  single 
simple  sharp  anticlinal  underground. §  The  breadth  of 
limestone  at  Orbisonia  gap  is  only  2600'  feet ;  and  the  thick- 
ness of  Trenton  limestone  about  500';  from  under  which  rise 
only  the  upper  beds  of  the  Chazy  (lib)  on  the  two  crests  of 
the  wave.  | 

The  fact  that  no  limonite  ore  has  been  found  in  Black 
Log  Valley  goes  far  to  support  the  view  that  there  is  really 

*  D'Invillier's  Report  F3,  1891,  p.  237. 

t  There  are,  however,  steep  dips  in  some  places.  On  the  creek  road  from 
Belleville  to  Union  Mills  the  beds  dip  65°  and  68°,  S.  55°  E.  At  the  quarry 
on  Yoder's  farm  the  stone  looks  more  like  slate  than  limestone;  and  this  is 
the  characteristic  feature  of  the  Trenton  beds  in  middle  Pennsylvania.  The 
Trenton  is  in  fact  a  transition  formation  from  the  magnesian  II  to  the  argil- 
laceous III.  The  Utica  slate  here  dips  60°,  N.  W.  (T3,  238). 

JSee  Geol.  Atlas  of  Counties,  Report  X,  1885,  Map  of  Huntingdon  No. 
31,  and  preface  descriptions,  p.  57. 

§  A  cross-section  will  be  given  in  a  future  chapter. 

j|  The  Grove  quarry  seems  to  show  the  limit  of  the  Trenton  beds  down- 
ward, and  the  top  bed  of  the  Chazy,  by  the  following  analyses  in  Ashburn- 
er's  Report  F,  1876,  p.  260.  Carbonate  of  lime  in  top  bed  (22"  thick)  90.16. 
Then  follow  downwards  84.68,  89.68,  74.18,  81.18,82.60,80.68,82.18,  85.18,  and 
then  the  bottom  bed,  only  46.68,  which  may  be  assumed  as  the  top  of  the 
Chazy. 


VALLEYS   AND   COVES   OF   NO.   II.  423 

no  limonite  horizon  at  the  junction  of  II  and  III ;  that  is, 
at  the  top  of  the  Trenton,  and  at  the  bottom  of  the  Utica. 

McConnellsburg  cove. 

TheMcConnellsburg  cove  in  Fulton  county,  is  a  canoe- 
shaped  valley  with  pointed  N.  E.  and  S.  W.  ends,  enclosed  in 
mountain  walls  of  Medina  sandstone(IV),  with  slopes  of  Hud- 
son river  slates  (III),  and  a  fertile  floor  of  limestone  (II),  13 
miles  long  by  2  miles  wide.  It  differs  from  all  the  other 
coves  in  having  along  its  N.  W.  side  a  profound  fault,  the 
limestone  (II)  being  upthrown  80CO'  against  Devonian  strata 
(VIII).  This  fault  swallows  up  the  slate  (III)  and  sand- 
stone (IV)  and  consequently  destroys  the  mountain  wall  on 
the  N.  W.  side  of  the  cove.* 

The  limestone  beds  at  McConnellsburg  and  between  that 
village  and  the  school  house  dip  55°  towards  the  fault  (W.) 
and  are  mostly  silicious,  with  much  honey-comb  chert,  and 
so  red  a  soil  in  some  places  as  to  suggest  a  good  deal  of 
limonite  iron  ore.  At  Sargent's  Rocks,  in  the  southern 
end  of  the  Cove,  are  the  extensive  old  limonite  banks  of 
the  Hanover  Iron  Works,  worked  for  about  25  years,  and 
abandoned  in  1847.  The  annual  yield  of  ore  is  said  to  have 
varied  between  1200  and  2000  tons,  and  much  ore  is  sup- 
posed to  remain.  Its  horizon  is  high  in  the  formation.! 
The  furnace  got  also  some  ore  from  the  Patterson  place,  on 
the  eastern  road  towards  the  pike,  and  trial  pits  were  sunk 
on  the  Nelson  farm,  but  all  such  work  was  abandoned  forty 
years  ago;  and  the  development  of  the  ores  of  the  Cove  is 
still  to  be  made. 

The  underground  erosion  of  the  limestone  strata  is  vari- 
ously illustrated  in  the  Cove.  Its  south  end  is  drained  by 
Esther's  run,  heading  in  the  high  vale  between  Cove 
and  Dickey's  mountains.  In  about  4  miles  it  sinks,  and 
rises  again  in  the  Big  Spring ;  then  cuts  through  the  Me- 

*A  description  of  the  fault  is  given  by  Stevenson  in  his  Report  T2,  p.  55, 
56 ;  and  details  of  its  exhibition  in  his  subsequent  chapter  XIII  on  Ayr,  Todd 
and  Dublin  townships,  T2,  p.  291  et  seq. 

t  Analysis  by  McCreath:  Iron,  46.1;  sulphur,  0.115;  phosphorus,  0.083;  sil. 
mat,  21.5  (T2,  p.  296). 


424  GEOLOGICAL    SURVEY    OF    PENNSYLVANIA. 

dina  ridge,   and  joins  Cove  creek  between  the  Lutheran 
Church  and  Elysian  Mills.* 

Horse  Valley. 

Horse  Valley  at  the  S.  W.  end  of  Perry  county,  con- 
tains a  narrow  belt  of  limestone  land,  with  two  points  or 
prongs  at  its  north  end,  where  the  anticlinal  has  two  crests, 
and  only  one  point  at  its  south  end,  where  the  anticlinal  is 
simple.  It  is  one  of  the  branches  of  Path  Valley  in  Frank- 
lin county,  and  almost  its  whole  floor  is  made  by  the  slates 
of  III.  Occasional  pieces  of  limestone  have  been  found 
near  the  gap.f 

*  The  drainage  of  the  Cove  is  very  curious  as  shown  on  the  colored  map  of 
Fulton  county  in  Report  T2.  The  natural  course  of  Esther's  creek  would 
have  been  around  the  N.  end  of  Lowrie's  Knob  instead  of  through  a  gap  in 
the  ridge  (IV).  So  also  at  the  northern  end  of  the  Cove,  the  drainage  ought 
all  to  flow  south  past  McConnellsburg  into  Cove  creek.  Instead  of  that,  it 
gathers  itself  by  streams  that  flow  N.  as  well  as  S.  and  W.  into  Licking  creek, 
which  breaks  a  gap  through  the  Medina  mountain  (IV)  at  Knobsville. 

f  See  Geol.  Hand  Atlas,  Report  X,  1885,  Map  No.  45,  and  Preface  p.  85. 
Dr.  Henderson  made  the  top  beds  of  II  reach  the  surface.  But  Prof.  Clay- 
pole  could  not  satisfy  himself  of  the  fact,  and  drew  his  cross-section  as  if 
the  limestone  did  not  See  his  Report  F2,  page  352,  and  his  section  on  page 
350,  which  I  reproduce  in  a  future  chapter. 


CAVERNS    IN    NO.    II.  425 


CHAPTER  XXXVI. 
Caverns  and  sinkholes  in  II. 

The  whole  surface  of  the  limestone  belt  of  the  Great  Val- 
ley is  pitted  with  sinkholes  in  the  farmers'  fields.  By  these 
holes  the  rainfall  escapes  into  caverns,  which  ramify  in  all 
directions  both  along  and  across  the  stratification,  and  re- 
appears in  springs  in  the  beds  of  the  deeper  valleys.  This 
explains  the  scarcity  of  brooks  and  creeks  on  the  maps  of 
the  limestone  belt  in  the  Great  Valley  ;  and  on  the  maps  of 
Kishicoquillis  and  Nittany  valleys  and  their  branches,  and 
the  limestone  coves  of  Fulton  and  Bedford  counties. 

Many  ancient  caverns  are  now  dry,  the  drainage  having 
opened  for  itself  new  ones.  Others  have  been  deserted  be- 
cause completely  choked  .and  filled  with  lime-iron  clays  and 
ore.  Others  have  been  exposed  to  the  sunlight  by  the  fall- 
ing in  of  their  roofs,  and  converted  into  vales  by  the  solu- 
tion of  their  walls.  Those  which  were  filled  with  deposits 
arid  then  uncovered  form  the  limonite  iron  mines  of  the 
present  day.* 

*A  most  instructive  case  is  described  by  Prof.  Ewing  in  his  special  report 
embodied  in  Report  T4  on  Centre  county,  at  page  418.  I  give  his  descrip- 
tion verbatim,  as  follows : 

''Cavern  deposit  of  iron  ore.  On  Sinking  creek,  as  it  rounds  Egg  hill,  in 
Potter  township,  on  the  Wagner  place  (A.  Kerr,  in  county  atlas),  is  an  ex- 
posure of  ore  quite  unique  in  many  respects.  The  ore  occupies  caverns 
eroded  out  of  the  limestone.  In  this  exposure  most  of  the  limestone  is  left 
intact.  The  ore  that  has  been  removed  has  been  taken  from  openings  into 
the  solid  mass  where  erosion  has  removed  the  material  from  one  side.  Even 
there  it  is  necessary  to  remove  large  quantities  of  limestone  in  order  to  get 
the  ore.  Large  masses  of  pipe  ore  are  found,  with  lump  ore,  bomb  shell  ore, 
and  wash  ore.  Most  of  the  ore  taken  out  has  been  removed  from  one  large 
triangular  space,  having  sides  about  20  feet  in  extent,  and  a  depth  of  15  feet, 
one  side  forming  an  opening  from  the  bank  of  the  creek-bed.  Besides  this, 
several  small  test-holes,  drift,  and  slant  openings  have  been  made.  Those 
within  a  range  covering  not  more  than  20  or  25  feet  in  thickness  of  rocks 
strike  ore  of  the  same  character  ;  those  out  of  this  range  show  but  little  ore. 
The  ore  is  found  in  the  worn  joints  imbedded  in  a  tenaceous  red  or  yellow 
clay. 

"As  pipe  ores  are  undoubtedly  formed  by  the  evaporation  of  chalybeate 


426  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

Shifting  creek  in  Blair  county  offers  a  fine  example  of  the 
extensive  underground  chemical  erosion  of  limestone  beds 
in  the  upper  part  of  No.  II.  Its  Arch  spring  became 
famous  among  the  white  settlers  at  an  early  date.*  The 

waters,  which  percolate  through  the  mass,  one  might  expect  to  find  in  a 
place  like  this  evidence  as  to  the  time  of  the  formation  of  these  pipes.  The 
fact  that  all  are  broken  off — none  being  attached  to  the  limestone — implies 
that  they  were  formed  at  a  sufficiently  remote  period  for  subsequent  waters 
to  dissolve  away  the  attachments.  The  fact  that  the  pipes  are  straight  and 
generally  parallel,  implies  that  they  were  formed  while  the  rocks  were  sta- 
tionary, and  not  during  a  gradual  upheaval.  It  is  inconceivable  that  they 
were  formed  while  the  rocks  were  in  their  original  horizontal  position  ; 
hence,  it  is  altogether  probable  that  they  were  formed  after  the  Appalach- 
ian upheaval,  and  while  the  rocks  were  in  their  present  position,  that  is, 
dipping  45°  S.  E. 

"One  very  interesting  specimen  from  this  region  has  one  of  the  pipes  at  an 
angle  of  40°  with  the  rest.  I  think  it  probable  that  in  this  case  the  pipe  had 
broken  in  falling,  and  had  been  cemented  by  subsequent  depositions  of  the 
same  material,  as  there  is  abundant  evidence  of  later  depositions  in  thread- 
like pipes  at  right  angles  with  the  larger  ones. 

"As  previously  remarked,  the  probable  condition  of  the  ore  while  in  so- 
lution, and  at  the  time  of  deposition,  was  that  of  a  ferrous  carbonate.  It  is 
probable  that  oxidation  began  at  the  time  of,  or  soon  after,  deposition.  When 
the  deposition  was  rapid,  masses  of  carbonate  and  semi-carbonate  were 
doubtless  formed,  which  have  subsequently  been  oxidized.  Evidence  of 
this  is  seen  in  the  larger  masses  found,  especially  here,  of  ore  containing 
cavities,  giving  it  a  porous  appearance,  often  called  bomb-shell  ore ;  for  as 
the  carbonate  of  a  low  specific  gravity  changes  to  the  oxide  of  a  higher  spe- 
cific gravity  thei-e  is  a  loss  in  volume.  The  change  naturally  beginning  from 
without  forms  concentric  layers  of  the  oxide  and  leaves  cavities  within. 
Even  the  pipe  ore  is  more  or  less  porous." 

*  Captain  John  S.  McKiernan,  who  moved  from  Blair  into  Clearfield,  sent 
to  the  Tyrone  Herald,  March  11,  1886,  the  following  slip  from  a  very  old 
newspaper :  "Among  the  other  curiosities  of  this  place,  is  the  swallows 
which  absorb  several  of  the  largest  streams  of  the  valley,  and  after  convey- 
ing them  several  miles  under  ground,  in  a  subterraneous  course,  return 
them  again  to  the  surface.  These  subterraneous  passages  have  given  rise  to 
the  name  'Sinking  Spring  Valley.'  Of  these  the  most  remarkable  is  called 
Arch  Springs,  and  runs  close  upon  the  road  from  the  town  to  the  fort.  It  is 
a  deep  hollow,  formed  in  the  limestone  rock,  about  thirty  feet  wide,  with  a 
rude  natural  stone  arch  hanging  over  it,  forming  a  passage  for  the  water, 
which  it  throws  out  with  some  degree  of  violence,  and  in  such  plenty  as  to 
form  a  fine  stream,  which  at  length  buries  itself  in  the  bowels  of  the  earth. 
Some  of  these  pits  are  near  300  feet  deep  ;  the  water  at  the  bottom  seems  in 
rapid  motion,  and  is  apparently  as  black  as  ink,  though  it  is  as  pure  as  the 
finest  springs  can  produce.  Many  of  these  pits  are  placed  along  the  course 
of  this  subterraneous  river,  which  soon  after  takes  an  opportunity  of  an 
opening  at  a  declivity  of  the  ground  and  keeps  along  the  surface  among  the 
rocky  hills  for  a  few  rods,  then  enters  the  mouth  of  a  large  cave,  whose  ex- 


CAVERNS   IN   NO.    II.  427 

creek  rises  on  the  high  ground  of  the  Kettle  at  the  south 
end  of  the  valley,  and  flows  along  the  exis  of  the  anticlinal 
for  3£  miles  ;  then  works  over  to  the  east  side  of  the  valley 
and  flows  in  the  upper  limestones  at  the  foot  of  the  mount- 
ain for  two  miles  ;  disappears  in  a  large  sink  hole  and 
flows  underground  a  mile,  its  "hollow"  or  surface  channel 
being  dry.  Another  creek,  heading  near  the  Bald  Eagle 
mountain,  on  the  west  side  of  the  valley,  and  flowing  square 
across  it  to  the  hollow,  meets  a  brook  descending  from  the 
east  mountain  terrace  and  flows  one  or  two  miles  further 
along  the  hollow,  according  to  the  wetness  or  dryness  of 
the  season,  and  disappears  gradually  through  a  succession 
of  sinkholes.  A  third  creek  starts  in  the  center  of  the  val- 
ley five  miles  north  of  the  last  mentioned,  flows  across  east- 
ward 1^  miles,  enters  a  large  cave,  flows  under  its  roof  4200 
feet,  issues  from  a  picturesque  arch  at  the  N.  E.  end  of  the 
cave,  and  thence  flows  through  a  flat  to  the  river  at  Union 
Furnace. 

Elk  run  follows  the  opposite  or  N.  W.  outcrop  of  the 
same  limestone  beds  at  the  foot  of  Bald  Eagle  (Brush) 
mountain,  cutting  a  deep  narrow  trench  to  the  river  at 
Tyrone  forges  ;  and  this  trench  merely  represents  a  similar 
series  of  sink-holes  and  caves  which  have  lost  their  roofs. 
All  the  brooks  descending  from  the  terrace  further  south 
than  the  head  of  Elk  run,  fora  distance  of  two  miles,  sink 
as  soon  as  they  pass  the  edge  of  the  slate  belt  and  enter  the 
limestone  land.  Of  course  their  waters  rise  somewhere  to 

terior  aperture  would  be  sufficient  to  admit  a  shallop  with  her  sails  spread. 
In  the  inside  it  keeps  from  18  to  20  feet  wide.  The  roof  declines  as  you  ad- 
vance, and  a  ledge  of  loose,  rugged  rocks  keeps  in  tolerable  order  on  one 
side,  affording  means  to  scramble  along.  In  the  midst  of  this  cave  is  much 
timber,  bodies  of  trees,  branches,  etc.,  which  being  lodged  up  to  the  roof  of 
this  passage,  shows  that  the  water  is  swelled  up  to  the  very  top  during 
freshets.  This  opening  in  the  hill  continues  about  400  yards  when  the  cave 
widens,  after  you  have  got  round  a  sudden  turning  point  (which  prevents 
its  being  discovered  till  you  are  within  it)  into  a  spacious  room,  at  the  bot- 
tom of  which  is  a  vortex.  The  water  falls  into  it,  whirling  round  with  amaz- 
ing force  ;  sticks,  or  even  pieces  of  timber  are  immediately  absorbed  and 
carried  out  of  sight,  the  water  boiling  up  with  excessive  violence,  which 
subsides  by  degrees  until  the  experiment  is  renewed." 


428  GEOLOGICAL   SURVEY    OF   PENNSYLVANIA. 

augment  Elk  run  ;  just  as  all  the  waters  of  the  Sinking  creek 
system  issue  at  Arch  Springs.* 

A  cave  in  Gregg  township,  Centre  county,  is  described 
by  Prof.  Ewing  as  typical  of  the  many  which  ramify  be- 
neath Nittany  and  Brush  valleys.  It  is  about  a  mile  west 
of  the  end  of  Brash  mountain  ;  on  the  43°  S.  E.  dip  of  that 
synclinal ;  in  dark  blue  limestone,  possibly  near  the  middle 
of  formation  II.  f 

The  "Hollows"  of  our  limestone  country  are  not  ordi- 
nary valleys  of  erosion  but  unroofed  ancient  caverns.  This 
is  apparent  from  their  peculiar  shape,  and  the  fact  that 
many  of  them  are  dry,  that  is,  have  no  flowing  streams, 
but  are  studded  with  sink-holes  into  which  the  rainfall  dis- 
appears to  caverns  beneath  them  which  have  been  subse- 
quently formed.  Prof.  Ewing  describes  one  known  as  the 
Big  Hollow,  in  Centre  county.:}: 

*Fine  pictures  of  these  arches  and  caves  were  made  by  Prof.  Rogers' ac- 
complished Swiss  artist,  Mr.  Lehman,  and  published  in  the  Geology  of  Penn- 
sylvania, 1858,  Vol.  I.  They  will  be  found  (reduced)  in  a  future  plate. 

f  In  Report  T4,  p.  442.  "  The  entrance  is  from  a  deep  sink.  It  extends 
along  the  strike  of  the  rocks  and  contains  deep  clear  water.  It  is  suffi- 
ciently large  to  allow  navigation  in  a  large  row-boat  Its  height  in  places 
is  20  or  30  feet,  and  its  breadth  about  the  same.  The  roof  of  the  cave  is 
formed  for  the  most  part  by  one  thick  stratum  of  limestone.  In  places, 
however,  this  has  fallen  away,  leaving  exposed  the  strata  above.  The  cave 
extends  1200  feet  beneath  the  surface.  At  the  far  end  the  rocks  dip  in  a 
more  easterly  direction,  so  that  the  roof  comes  down  to  the  surface  of  the 
water.  About  300  feet  in,  the  cave  divides  into  two  parts,  one  wet,  the  other 
dry,  the  same  stratum  forming  the  roof  ot  both.  The  side  toward  which  the 
rocks  dip  contains  the  water,  the  more  open  side  apparently  having  its 
bottom  filled  by  the  d&bris  fallen  from  above.  The  two  arms  are  separated 
by  a  natural  partition  of  uneroded  rocks.  The  dry  cave  may  be  reached  by 
another  sink  in  line  with  the  opening  alluded  to.  Within  the  cave  are  stal- 
agmites and  stalactites  of  every  variety  of  form. 

"About  80  feet  from  the  far  end  of  the  cave  is  a  deep  ravine,  and  the 
Fathomless  /Spring  known  as  the  source  of  Penn  creek.  As  the  water  in 
the  spring  stands  at  the  same  level  as  that  in  the  cave,  the  two  are  probably 
connected  ;  and  the  cave  is  no  doubt  only  one  section  of  a  much  larger  sys- 
tem of  underground  drainage  ;  for,  a  short  distance  nearly  west  of  the  cave 
a  stream  sinks  beneath  the  surface,  and  is  probably  identical  with  that  which 
appears  as  Penn  creek." 

JT4,  p.  442.  "Several  beds  of  ancient  streams  are  noticeable  in  this  lo- 
cality. One  of  the  most  extensive  of  these  appears  to  originate  near  Johns- 
ton's ore  bank.  Here  several  indistinct  depressions  converge  into  one  ravine 
which  crosses  the  road  passing  northeast  of  Struble's  bank.  The  Bellefonte 
and  Buffalo  Run  RR.  grade  follows  this  ravine  to  thecurve  near  Thompson's, 


CAVERNS    IN    NO.    II.  429 

Of  the  innumerable  limestone  caverns  of  Pennsylvania 
very  few  have  been  explored,  most  of  them  are  inaccessi- 
ble, and  the  existence  of  a  great  number  of  them  is  only 
indicated  by  sink  holes  in  the  farm  fields. 

One  of  the  most  interesting  is  the  Hartman  cave  (now  the 
Crystal  Hiil  cave)  in  Monroe  county,  which  was  explored 
in  1880,  and  found  to  be  floored  by  10'  of  clay,  on  which 
was  spread  a  thin  layer  of  stalagmite,  and  on  this  again  a 
foot  of  black  earth  containing  the  teeth  and  bones  of  ani- 
mals of  both  extinct  and  living  species,  mostly  broken, 
splintered  and  gnawed  by  large  and  small  carnivorous  beasts 
which  at  one  time  made  the  cave  their  home,  dragging  into 
it  their  prey  to  be  devoured.* 

where  a  branch  ravine  joins  it ;  which  the  grade  follows  upward,  diagonally, 
through  the  Barrens.  This  ravine  is  traceable  to  the  vicinity  of  the  Pond 
bank. 

"The  main  ravine,  known  as  Big  hollow,  continues  in  a  sinuous  course 
northeastward  until  it  reaches  Spring  creek,  one  mile  below  Houserville. 
Big  hollow  has  a  distinct  course  of  about  five  miles  ;  its  banks  are  in  places 
from  50  to  100  feet  high,  here  sloping  and  gradual,  there  steep  and  precipi- 
tous. As  in  the  case  of  real  river  channels,  the  steep  banks  are  on  the  inside 
of  the  curves. 

"  The  whole  topography  of  Big  hollow  indicates  that  it  is  the  bed  of  an  an. 
cient  stream.  An  extensive  area  slopes  toward  this  ravine.  Several  smaller 
ones  join  it  on  its  course,  yet  I  know  of  no  evidence  that  water  has  flowed 
through  it  since  the  first  settlement  of  Centre  county  ;  but  I  have  found 
numerous  sink-holes  along  the  channel ;  and  gravel  deposits  and  other  de- 
bris in  the  vicinity  of  some  of  them  indicate  that  large  quantities  of  water 
have  flowed  into  them  in  times  of  freshet ;  and  this  makes  it  probable  that 
there  exists  beneath  the  Big  hollow  an  underground  channel  joining  Spring 
creek." 

*The  report  of  the  exploration,  made  by  Mr.  Paret,  Prof.  Porter  and  Dr. 
Joseph  Leidy,  was  published  in  the  Annual  Report  of  the  Geo.  Sur.Pa.  for 
1887,  pp.  1  to  20,  with  two  plates  by  Dr.  Leidy,  who  identified  the  remains  of 
the  living  lynx,  gray  fox,  wolf,  skunk,  weasel,  raccoon,  mole,  dusky  bat? 
little  brown  bat,  woodchuck,  porcupine,  beaver,  musk  rat,  gray  squirrel, 
ground  squirrel,  meadow  mouse,  white  footed  mouse,  wood  rat,  gray  rab- 
bit, deer,  elk  ; — no  domestic  animal,  except  perhaps  a  pair  of  imperfectly  de- 
veloped teeth  of  a  horse  ;— many  bird  bones,  especially  of  the  wild  turkey 
several  kinds  of  turtles  and  snakes  ; — snail  shells,  a  valve  of  the  river  mus- 
sel, and  two  other  shells  ; — some  small  fragments  of  charcoal ;  many  seeds 
of  dogwood,  pignut,  walnut  ;— works  of  man,  a  bone  fish  hook,  harpoon 
head,  5  bone  awls,  a  bone  needle,  a  bored  cone  shell,  a  chipped  spear  head 
of  argillite,  a  black  flint  knife  and  a  piece  of  brown  pottery. 

But  with  all  the  above  were  found  remains  of  the  extinct  peccary  (Dicoty- 


430  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

A  vertical  cavern  in  the  limestones  of  II  was  exposed  by 
quarry  work  in  the  Chester  county  valley  near  Port  Ken- 
neday,  and  explored  by  Mr.  Wheatley,  of  Phoenixville ; 
the  animal  remains  being  described  by  Prof.  Cope.  These 
were  all  of  a  comparatively  recent  geological  age.  This 
fact,  taken  in  connection  with  the  Tertiary  lignite  beds  of 
the  Pond  bank  in  Franklin  county,  and  the  Ironton  mine 
in  Lehigli  county,  prove  that  all  our  caverns  are  of  geologic- 
ally modern  construction,  and  belong  not  at  all  to  the  re- 
mote dates  of  the  limestone  formations  which  they  pene- 
trate ;  that  they  are  in  fact  the  last  descendants  of  an  infi- 
nite series  of  caves  excavated  in  successive  ages,  and  un- 
roofed and  swept  away  as  the  unceasing  erosion  by  atmos- 
pheric waters  lowered  the  original  surface  of  the  globe  to 
its  present  level.  The  rate  at  which  this  erosion  has  gone 
on  deserves  consideration. 

The  rate  of  erosion. 

The  rate  at  which  the  surface  of  our  limestone  valleys  has 
been  lowered  is  hard  to  calculate.  It  depends  (1)  on  the 
amount  of  rainfall  from  year  to  year  and  from  age  to  age  ; 
(2)  on  the  way  the  rain  falls,  whether  in  a  perpetual  drizzle, 
or  in  violent  downpours  ;  (3)  on  the  slope  of  the  beds  of  the 
water  channels,  whether  more  or  less  steeply  inclined  ;  (4) 
on  the  solubility  of  the  rocks,  both  in  general  and  in  par- 
ticular, determining  the  shape  and  size  of  caverns,  the  sta- 
bility of  their  roofs,  and  consequently  the  amount  of  me- 
chanical erosion  which  is  in  addition  to  the  amount  of 
chemical  solution. 

Undoubtedly  a  part  of  our  limestone  formation  passes  off 
to  the  ocean  as  lime  water ;  but  another  part  passes  off  as 
broken  matter,  floated  limestone  pieces,  limestone  sand, 
limestone  mud.  And  when  the  new  oceanic  deposit  is 
made  it  must  represent  both  these  forms  ;  as  we  see  that  it 
does  ;  for  the  microscope  shows  mechanical  fragments 
cemented  by  a  chemical  precipitate. 

les  pcnnsylvanicus) ;  of  another  larger  extinct  peccary  (Platygonus  vctus}; 
and  of  the  extinct  gigantic  beaver  (Castoroides  ohioensis.*) 

This  cave,  not  being  in  No.  II,  but  in  the  lower  Helderberg  limestone  No. 
VI,  will  be  more  properly  described  in  a  future  chapter. 


CAVERNS    IN   NO.    II.  431 

The  chemical  solution  of  the  limestone  strata  of  Centre 
county  was  studied  by  Prof.  A.  L.  Ewing  in  1883*,  at  the 
upper  end  of  the  Old  Bellefonte  dam,  below  the  entrance  of 
all  visible  tributaries  of  Spring  creek.  (1)  The  cross-sec- 
tion and  velocity  of  the  stream  were  here  measured  ;  (2) 
the  amount  of  solids  in  the  water  was  determined  by  evapo- 
ration ;  (3)  the  area  of  the  whole  water  basin  was  calcu- 
lated geographically. 

1.  The  average  width,  75' ;  average  depth  (six  measure- 
ments), 2.7' ;  average  velocity  (got  by  bottles  floated  at  va- 
rious depths),  3263'  per  hour  =  about  24, ,500  cubic  yards 
of  water  passing  a  given  point  every  hour. 

2.  By  evaporation  (two  tests),  2400  grains  of  solid  matter 
were  got  from  one  cubic  yard  of  water  ;  according  to  which 
(24,500x24x365x2400-5-7000=)  73,584, 000  Ibs.,  or  328,500 
long  tons  of  solid  matter  carried  away  per  annum. 

3.  The  area  drained  by  Spring  creek  is  rudely  estimated 
at  100  square  miles,  three-fourths  of  which  is  mountain 
slope  ;  the  rest  limestone  valley.     By  evaporating  mount- 
ain water  it  was  found  that  nine-tenths  of  the  solid  matter 
in  Spring  creek  came  from  the  limestone  valley. 

Prof.  Ewing  calculated  the  annual  waste  of  the  region  at 
282  tons  per  square  mile  ;  and  the  waste  of  the  limestone 
valley  by  solution  at  275  tons  per  square  mile. 

Taking  the  specific  gravity  of  limestone  at  2.75  (Traut- 
wine,  p.  386),  a  layer  one  foot  deep  over  a  square  mile  would 
weigh  2,140,540  gross  tons.  A  layer  of  275  tons  would  be 
only  one-eight  thousandth  (^oW)  °f  an  mc^  thick.  In 
other  words  the  surface  of  Nittany  valley  is  lowered  at  the 
rate  of  one  foot  in  eight  thousand  years  by  the  loss  of  what 
is  constantly  running  off  past  Bellefcnte,  so  far  as  that  can 
be  calculated  in  the  manner  described  above. 

Other  things,  however,  have  to  be  taken  into  considera- 
tion which  should  vitiate  the  correctness  of  that  result 
without  substituting  for  it  another  more  reliable.  The 
loose  stones  in  the  main  channel  and  in  all  its  branch  water 
ways  show  that  annual  floods  play  a  role  of  great  import- 

*Proc.  Am.  Ass.  Adv.  Science,  1884;  copied  into  Report  of  Prog.  G.  Sur. 
of  P.,  T3,  451. 


432  GEOLOGICAL    SURVEY    OF    PENNSYLVANIA. 

ance  in  the  operation  ;  frost  loosening  the  limestone  slabs, 
and  water  breaking  them  into  pieces,  grinding  them  to- 
gether, and  sweeping  them  away  into  the  Susquehanna 
river  and  so  onward  into  the  sea.  The  rate  of  this  mechan- 
ical destruction  of  the  surface  is  unknown,  and  probably 
cannot  be  in  any  manner  calculated.  It'  it  be  assumed  equal 
to  the  rate  of  chemical  solution,  the  surface  of  the  country 
may  be  said  to  lower  itself  one  foot  in  4000  years. 

But  even  this  more  rapid  rate  cannot  be  adopted  for  cal- 
culations extended  backward  many  ages  ;  for,  while  the 
chemical  solution  is  a  constant  quantity,  provided  the  an- 
nual rainfall  be  a  constant  quantity^  the  rate  of  mechanical 
erosion  depends  on  the  velocity  of  streams,  i.  e.  on  the  slope 
of  the  water-basin.  But  this  was  much  greater  in  past 
ages  than  it  is  now.  When  the  top  limestones  on  the  Belle- 
fonte  and  other  anticlinals  were  first  laid  bare  the  general 
surface  of  the  region  had  a  topography  exactly  resembling 
that  of  the  Shade  and  Black  Log  region  at  the  present  day  ; 
but  it  had  an  elevation  above  the  sea  at  least  5000  feet 
higher.  Of  course  erosion  went  on  at  its  usual  high  rate 
in  Alpine  regions  ;  but  as  we  have  no  data  for  calculation, 
it  is  left  to  the  imagination  of  the  student  of  nature  to 
adopt  a  mean  rate  between  the  extremes  of  excessive  me- 
chanical erosion  at  the  outset  and  of  excessive  chemical 
solution  now. 

At  present  the  water  fall  from  the  head  of  Spring  creek 
(1290'  A.  T.)*  in  Penn's  valley  to  the  dam  at  Bellefonte  is 
only  about  57C',  and  from  Bellefonte  to  tide  water  in  Chesa- 
peake Bay  about  720'  At  the  birth  of  Nittany  valley  the 
fall  of  the  Spring  creek  which  then  traversed  it  lengthwise 
(as  Black  Log  creek  traverses  its  valley)  was  say  500',  and 
of  the  Susqnehanna  river  which  then  existed  say  5000'. 
The  rate  of  surface  erosion  may  well  have  been  then  400  or 
even  100  years  per  foot. 

All  such  calculations  are  therefore  fruitless,  seeing  that 
the  age  of  Nittany  valley  can  be  made  at  will  either  40, 000,- 
000,  20,000,000,  2,000,000  or  only  500,000  years.  If  we  go 
back  beyond  the  uncovering  of  the  top  limestones  of  No. 

*T4,  419. 


CAVERN    DEPOSITS    IN    NO.    II.  433 

II  on  the  Bellfonte  anticlinal  to  the  coal  age,  we  greatly 
increase  the  time,  but  not  in  proportion  to  the  thickness 
of  the  overlying  formations  ;  for,  the  erosion  must  have 
been  vastly  more  rapid  when  the  surface  stood  20,000'  or 
25,000'  above  the  sea. 

In  fact  this  part  of  our  science  is  nothing  but  a  fairy 
tale  ;  and  the  best  geologist  is  merely  the  most  lively  ra- 
conteur. 

Precipitation  of  limonite  in  caves. 

The  rate  of  deposit  of  limonite  (hydrous  peroxide  of 
iron)  in  cavities  is  sometimes,  under  favorable  circum- 
stances, quite  rapid.  For  example,  at  the  Bennington 
shaft  near  the  Allegheny  mountain  summit  tunnel  of  the 
P.  RR.  in  Blair  county  "the  pump  column"  receives  from 
the  mine  water  one  inch  of  such  deposit  each  year,  supplied 
by  the  decomposition  and  oxidation  of  carbonate  iron  ore 
balls  in  the  roof  shales  of  the  Miller  coal  bed.  And  again, 
at  Johnstown,  in  the  Slope  mine,  an  area  of  half  an  acre 
(near  New  Furnace  No.  5)  is  now  being  filled  with  limonite 
mud  from  the  same  source  (viz :  decomposition  of  ore  balls 
in  roof)  so  rapidly  that  a  layer  18  inches  in  depth  has  been 
made  in  the  course  of  the  last  eight  years  ;  so  that  it  looks 
as  if  the  whole  space  once  'occupied  by  the  coal  bed  would 
in  a  few  years  more  be  occupied  by  a  consolidated  bed  of 
limonite  iron  ore.* 

*The  process  is  facilitated  in  this  instance  by  the  fact  that  some  warm  water 
from  the  large  furnace  works  passes  through  the  roof  of  the  mine.  (Report 
T,  p.  171.) 

The  deposit  of  iron  rust  in  the  municipal  purifying  revolvers  at  the  Ant_ 
werp  water  works  is  accompanied  by  physical  details  of  the  greatest  inter- 
est for  geologists  studying  the  theory  of  the  formation  of  limonite  deposits, 
including  organic  matter,  clays  of  various  colors  from  white  to  black,  and 
concretions.  "In  March,  1885,  three  of  these  revolvers  were  started  at  Ant- 
werp, and  the  original  iron  and  gravel  beds  were  converted  into  ordinary 
sand  filters  ;  by  this  change  the  capacity  of  the  works  was  at  once  doubled. 
The  total  weight  of  iron  in  use  at  one  time  was  reduced  from  900  tons  to  3J 
tons,  and  all  the  expenses  connected  with  digging  over  and  washing  the 
purifying  materials  were  done  away  with. 

"When  pure  water  is  passed  through  a  revolver,  a  certain  amount  of  iron 
is  dissolved,  and  then  the  water  flows  out  a  light  gray  color.  After  two  or 
three  hours,  the  color  changes  to  a  reddish  brown,  and  a  deposit  of  rust 

28 


434  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

Depth  of  limonite  deposits  in  caves. 

The  depth  of  a  limonife  ore-clay  mass  therefore  depends 
on  the  depth  of  the  cavern  floor ;  and  this  in  turn  depends 
upon  the  deepest  drainage  level  of  its  district. 

Theoretically  such  a  deposit  of  ore  ought  not  to  be  deeper 
than  the  place  where  its  ancient  water  course  came  out  on 
the  Lehigh  or  Schuylkill  river,  but,  considering  the  chem- 
ical action  of  the  water  on  the  floor  of  the  cavern,  and  in 
fissures  descending  beneath  the  floor,  some  slight  additional 
depth  must  be  allowed.  It  is  a  practical  geological  rule, 
however,  that  an  owner  of  ah  iron  bank  in  fterks  county 
cannot  expect  to  find  ore  below  the  plane  of  200'  above  tide, 
which  is  the  level  of  the  bed  of  the  Schuylkill  at  Reading, 
and  the  level  of  the  bed  of  the  Lehigh  at  Allen  town.  An 
allowance  must  also  be  made  for  the  grade  of  the  descent 
of  the  underground  water  from  the  mine  to  the  outlet.  An 
iron  bank  near  Reading  maybe  deeper,  therefore,  than  one 
at  Kutztown  or  at  Womelsdorf  can  be.  Topton  Junction, 
for  example,  stands  at  485'  A.  T.  Subtract  200'  from  485' 

takes  place  at  the  bottom  of  the  vessel.  If  filtered  at  once  on  escaping  from 
the  revolver  the  liquid  will  generally  be  clear  at  first,  but  after  a  time  it  will 
sometimes  get  cloudy  and  the  deposit  of  rust  will  take  place,  showing 
that  the  iron  existed  in  the  first  instance  in  solution,  and  was 
afterward  precipitated  by  the  action  of  atmospheric  oxygen.  If  the 
water  be  impure,  colored  and  charged  with  dissolved  organic  matter, 
it  will  issue  from  the  revolver  of  a  dark  gray  color,  and  this  will  increase 
to  an  inky  black  in  the  case  of  very  bad  water.  So  that  it  is  possible  to  judge 
of  the  quality  of  the  water  by  the  color  assumed  during  its  treatment.  If 
the  impurities  are  not  more  than  the  iron  can  deal  with,  the  liquid,  on  stand- 
ing for  some  three  or  four  hours,  becomes  lighter  and  lighter  in  color,  a 
black  precipitate  forms,  and  sinks  very  slowly  to  the  bottom,  the  color  be- 
comes a  dirty  gray,  and  then  the  water  will  filter  quite  clear  and  bright.  If 
the  impurities  overpower  the  iron,  or  are  of  a  nature  which  the  iron  cannot 
effectually  attack,  a  purplish  color  remains,  and  the  liquid  will  not  filter  col- 
orless. As  in  the  case  of  the  Bischof  filter,  the  time  of  repose  and  exposure 
to  the  air  before  filtration  is  obtained  by  providing  a  sufficient  depth  of 
water  over  the  sand  of  the  filter  beds. 

"In  addition  to  its  chemical  action,  iron  possesses  the  property  of  causing 
the  very  finely-divided  particles  of  matter,  which  cause  opalescence  and 
cloudiness,  to  coagulate  to  such  an  extent  that  they  can  be  removed  by  fil- 
tration. The  waters  of  the  Nile,  for  example,  which  will  not  subside  clear' 
in  any  reasonable  time,  and  which  cannot  be  filtered  bright  by  sand  filters, 
yield  a  beautiful  clear  water  if  agitated  with  iron  before  filtration  through 
sand."  Sci.  Amer.  Supp.,  No.  580,  p.  9260,  Feb.  12,  1887. 


CAVERN   DEPOSITS   IN   NO.    II.  435 

and  we  have  285'  as  the  possible  depth  of  a  cave  or  sink- 
hole. But  Topton  Junction  is  18-J  miles  from  Reading.  If 
we  only  allow  a  fall  of  5'  per  mile  for  the  cavern  waters  we 
must  take  off  92',  leaving  only  193'  for  the  possible  depth 
of  a  cave,  or  of  an  iron  ore  deposit  at  Topton  Junction. 
Beyond  some  such  properly  calculated  depth  sinking  for 
iron  ore  of  this  kind  is  a  hopeless  affair. 

The  filling  of  the  caverns,  however  large  and  numerous 
they  may  be,  is  easily  comprehensible  when  we  remember 
that  an  average  of  93  per  cent,  of  the  magnesian  limestone 
formation  rock  is  soluble,  and  when  dissolved  by  the  rainfall 
passes  off  entirely  into  the  sea.  Of  the  remaining  7  per 
cent,  of  insoluble  clay-iron  sand,  a  portion  would  be  carried 
away  by  rapid  waters,  but  a  portion  would  settle  and  remain 
in  quiet  pools  in  the  large  cavern  chambers,  and  would  en- 
tirely fill  such  galleries  as  were  kept  full  of  water  by  the 
choking  up  of  their  lower  exits. 

Limonite  precipitated  from  pyrites. 

Enough  is  said  on  this  subject  on  preceding  pages  lo 
suggest  inquiry,  for  no  sufficient  knowledge  of  it  has  yet 
been  obtained.  Dr.  T.  S.  Hunt  has  expressed  his  opinion 
strongly  that  all  our  limonite  deposits  have  had  this  origin. 
But  the  frequent  finding  of  crystals  and  pipes  of  pyrites  in 
the  ore  banks  is  not  of  itself  a  broad  enough  basis  for  so 
large  a  generalization,  and  many  of  the  facts  narrated  in 
preceding  chapters  seem  to  have  no  direct  connection  with 
such  a  process.  The  presence  of  magnetite,  however,  is  a 
detail  which  may  be  connected  with  that  of  pyrites.* 

*Mr.  W.  B.  Devereux,  of  Colorado,  has  published  in  Trans.  A.  Inst.  Min 
Engineers,  Feb.,  1884,  an  interesting  paper  on  the  Pitkin  county  iron  ores- 
which  he  concludes  with  the  following  paragraph  :  "  While  in  doubt  as  to 
the  relation  this  ore-body  bears  to  the  limestone,  I  hazard  the  opinion  that 
the  magnetite  is  a  direct  product  of  the  decomposition  of  iron  pyrites,  and 
that  the  ore-body  at  no  great  depth  is  massive  pyrites  instead  of  massive 
magnetite.  I  base  this  opinion  upon  the  following  facts  :  Crystals  of  mag- 
netite are  common  in  this  locality,  which  are  pseudomorphs,  showing  the 
common  hemi-hexahedral  form  and  characteristic  striations  of  pyrites.  Efflo- 
rescence of  ferrous  sulphate  is  also  common  ;  and  in  the  bed  of  the  ravine 
the  ore  is  a  mixture  of  pyrite  and  magnetite,  the  latter  appearing  as  a  fine- 
grained gray  matrix,  and,  when  pulverized  or  broken  off,  being  strongly 


436  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 


CHAPTER  XXXVII. 
Zinc,  Lead  and  Barium  in  No.  II. 

New  Jersey  has  its  great  Franklin  zinc  mine,  famous 
throughout  the  mineralogical  world  as  well  as  the  world  of 
commerce  and  the  arts.  Pennsylvania  has  its  one  great 
Saucon  mine  of  zinc  ore,  also  ;  and  two  other  zinc  mines  of 
no  commercial  importance,  but  equally  interesting  from  a 
geological  point  of  view  ;  all  three  being  precipitations  of 
salts  of  zinc  in  the  same  old  limestone  formation  of  No.  II. 

The  Saucon  zinc  mines  of  LeMgh  county. 

The  location  of  these  mines  is  shown  on  plate  XII,  page 
364,  above.  They  have  riveted  the  curious  attention  of  geol- 
ogists for  many  years,  as  they  have  given  occasion  to  some 
of  the  most  splendid  exhibitions  of  mining  engineering 
genius,  in  its  efforts  to  overcome  extraordinary  difficulties 
in  the  way  of  drainage.  The  mine  pumps  are  among  the 
greatest  in  the  world.  The  most  powerful  apparatus  that 
could  be  constructed  was  required  for  keeping  the  great 
excavation  dry  enough  to  work.  The  limestone  formation 
in  the  Saucon  valley  lies  in  a  deep  trough  into  which,  and 
to  the  bottom  of  which,  flows  the  rainfall  of  the  surround- 
ing mountains.  The  beds  are  uptilted  and  broken,  the 
innumerable  fissures  which  traverse  them  and  the  caverns 
which  have  been  excavated  in  them  permit  the  accumulation 

attracted  by  the  magnet.  This  rapidly  increasing  percentage  of  pyrite,  the 
occurrence  of  the  two  minerals  in  intimate  juxtaposition,  and  the  fact  that  no 
intermediate  stage  of  hematite  occurs,  taken  together  with  the  testimony  of 
the  pseudomorphs,  all  oppose  the  application  to  this  case  of  the  ordinarily 
accepted  theory  that  magnetite  is  a  metamorphic  derivative  from  hematite. 
Having  enjoyed  a  somewhat  extensive  observation  of  iron-ore  deposits,  and 
accepting,  as  satisfactory  in  many  cases  the  theory  just  mentioned,  yet  in  this 
case  I  can  see  nothing  which  will  permit  its  use  as  an  explanation  of  the 
i'acts.  This  ore  contains  a  trace  of  silver  also,  but  no  copper.  It  may  be  in- 
teresting to  note  that  pieces  of  the  limestone  referred  to,  when  struck  with 
a  hammer,  emit  the  odor  ofsulphureted  hydrogen." 


ZINC    MINES    IN    NO.    II.  437 

of  great  quantities 'of  water;  the  dissolution  of  the  lime 
rocks  has  produced  concentrated  masses  of  zinc  ore ;  and 
the  phenomena  of  our  great  brown  hematite  iron  ore  de- 
posits are  here  repeated,  zinc  being  substituted  in  the  place 
of  iron.  The  geological  cause  of  this  substitution  of  zinc 
for  iron  may  be  said  to  be  quite  unknown,  or  at  all  events 
has  not  yet  been  satisfactorily  explained  on  any  theory  ;  nor 
can  we  suggest  a  reason  why  some  of  the  beds  of  No.  II  in 
Saucon  valley  are  as  heavily  charged  with  zinc  as  are  the 
iron-bearing  beds  of  No.  II  elsewhere  in  the  State  with 
iron.  If  it  be  suggested  that  the  zinc  has  come  from  a  dis- 
tance, whether  from  above  or  below,  it  is  only  necessary  to 
point  to  certain  thin  beds  of  limestone,  carrying  zinc  which 
have  been  mined  to  a  small  extent  and  without  profit  in 
the  neighborhood  of  Penningtonville  in  Lancaster  county, 
and  of  similar  beds  of  limestone  carrying  both  lead  and  zinc 
which  have  been  repeatedly  mined  without  profit  in  Sink- 
ing valley  in  Blair  county.  In  the  last  mentioned  district 
of  the  State  two  sorts  of  unwise  notions  have  been  expressed 
regarding  these  zinc- bearing  beds.  (1)  They  have  been 
looked  upon  as  merely  veins  descending  into  the  interior 
of  the  globe.  Similar  veins  of  zinc  ore  do  in  fact  exist  in 
Sinking  valley,  opposite  Birmingham,  but  they  are  concen- 
trations of  the  zinc  and  lead  from  the  limestone  beds  of  the 
valley,  and  (2)  there  is  no  good  reason  for  believing  that 
they  are  connected  in  any  way  with  the  underground 
depths.  They  have  nothing  to  do  with  the  anticlinal  struc- 
ture of  Sinking  valley  any  more  than  the  zinc  ores  have 
with  the  monoclinal  structure  at  Penningtonville,  or  than 
the  zinc  ores  have  with  the  synclinal  or  basin  structure  of 
the  Saucon  valley.  The  fact  is,  that  zinc  and  lead  seem  to  be 
inherent  constituents  of  all  limestone  formations  the  world 
around.  It  is  probable  that  they  were  deposited  with  the 
limestone  in  far  grater  abundance  in  ancient  ages,  and  were 
originally  brought  into  the  Appalachian  sea  as  soluble 
salts,  together  with  the  lime  and  magnesia  waters  of  prim- 
eval rivers.  It  only  remains  to  add,  that  the  zinc  and  lead 
ores  of  Pennsylvania  correspond  in  all  respects  to  the  No. 
II  zinc  ores  of  Wythe  county,  Virginia,  and  to  the  great 


438  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

lead  and  zinc  deposits  in  the  fissures  and  caverns  of  the 
ancient  limestone  country  of  Wisconsin  and  Missouri. 
They  all  belong  to  the  same  remote  age,  and  have  been  con- 
centrated into  their  present  form  in  the  same  limestone 
formations  and  by  a  similar  process. 

The  Saucon  zinc  mine  at  Friedensburg  is  said  by  Rogers 
to  be  in  a  close  synclinal  fold.*  He  describes  it  as  merely 
a  surface  quarry  ;  but  it  had  only  been  started  in  1853,  and 
worked  three  years  by  a  slope  when  he  saw  it.  Its  calamine 
ore  or  silicate  of  zinc,  appeared  then  irregularly  injected 
into  the  limestone,  which  stood  vertical  in  the  N.  wall,  and 
dipped  85°  in  the  S.  wall.  The  limestone  was  also  injected 
with  thin  veins  of  quartz."f 

Prof.  Prime  in  his  Report  D3,  1883,  p.  239,  says  the  ore, 
zinc  blende,  associated  with  iron  pyrite,  is  disseminated 
through  a  limestone  which  seems  broken  up,  and  its  crevices 
filled  in  with  the  ore. 

The  mass  has  somewhat  the  appearance  of  a  breccia.  The 
zinc  blende  is  not  confined  to  one  bed  or  horizon,  but  ex- 
tends through  a  vertical  thickness  of  30  or  40  feet  in  some 
places,  while  at  other  points  of  the  mine  the  infiltration 
seems  confined  to  a  vertical  thickness  of  10  to  20  feet. 
The  mine  has  been  worked  (1877)  to  a  depth  of  250'  on  the 
slope  of  the  bed.  The  excavations  are  very  large  and  ex- 
tend along  the  strike  more  than  1000';  the  dip  of  the  lime- 
stone being  30°  to  35°,  S.  5°  to  10°  E. 

It  is  evident  that  the  source  of  the  ore  was  above,  and 
not  beneath  ;  that  the  term  "infiltration"  is  as  justly  used 
in  this  case  as  in  that  of  our  limonite  or  brown  hematite 
iron  ore  deposits.  That  the  zinc  was  an  original  constitu- 
ent of  the  limestone  is  extremely  doubtful.  And  yet  the 
fact  that  the  zinc  of  Pennsylvania  and  New  Jersey,  as  well 
as  of  the  western  states  occurs  in  No.  II.  seems  to  link  the 
metal  with  limestone  of  Lower  Silurian  age.  The  notion 
of  a  deep-seated  source  expressed  by  Mr.  F.  L.  Clark  in  his 

*Geol.  Pa.  1858,  p.  101.  On  page  236  he  suggests  that  the  synclinal  may 
be  faulted. 

f  The  ore  was  smelted  at  Bethlehem  and  converted  into  white  paint.  The 
vein  seemed  to  range  along  the  axis  of  the  synclinal  or  fault,  1856. 


ZINC    MINES   IN   NO.    II.     '  439 

paper  on  the  Mining  and  Metallurgy  of  Zinc  in  the  U.  S., 
published  in  the  "Engineer  and  Mining  Journal"  of  Sep- 
tember 8,  1883,  I  cannot  concede  to  ;  but  his  description 
of  the  mines  is  perhaps  the  best  we  have,  and  I  give  it  in  a 
foot-note.* 

*  The  zinc  deposits  in  the  Saucon  valley,  Lehigh  county,  Pennsylvania, 
which  were  once  extensively  worked,  now  produce  but  little  ore.  Their 
history,  however,  has  a  special  interest  from  their  connection  with  the  in- 
troduction of  spelter-making  into  this  country,  and  from  the  fact  that  they 
belong  to  a  class  of  deposits  which  seems  to  warrant  a  belief  in  their  con- 
tinuance to  a  considerable  depth,  and  because  they  are  a  good  illustration 
of  the  general  effect  of  the  characteristic  feature  of  the  ore  market  above  re- 
ferred to. 

Tbree  principal  deposits  have  been  discovered,  known  respectively  as  the 
Ueberoth,  Hartman  and  Saucon  mines  :  they  occur  in  magnesian  limestone 
of  the  Lower  Silurian  formation,  and  have  many  points  in  common,  while 
they  also  present  some  striking  differences.  They  were  all  at  one  time 
owned  or  controlled  by  the  Lehigh  Zinc  Company,  whose  works  were  at 
Bethlehem,  four  miles  distant. 

The  Ueberoth  mine,  which  is,  so  far  as  developments  have  shown,  the 
largest,  was  worked  continuously  from  1853  up  to  the  fall  of  1876.  It  was 
for  many  years  the  main  dependence  of  these  works,  and  produced  in  the 
neighborhood  ot  300,000  tons  of  ore.  The  strata  of  limestone  are  here  very 
much  disturbed  and  tilted  up  almost  to  the  vertical,  apparently  by  the  ob- 
trusion of  the  syenite  ridge  of  the  neighboring  South  mountain.  The  ore 
came  close  to  the  surface,  and  a  very  rich  pocket  was  found  in  the  clay 
above  and  around  limestone  boulders,  which  is  estimated  to  have  produced 
100,000  tons  of  ore.  When  this  body  of  ore  was  exhausted,  the  ore  was  fol- 
lowed down  in  crevices  between  the  boulders.  These  crevices  lie  in  planes 
parallel  to  the  bedding  of  the  limestone,  or  in  planes  perpendicular  to  it,  and 
preserve  great  regularity  in  their  position,  an  i  a  parallel  course  for  several 
hundred  yards  in  a  northeast  and  southwest  direction  ;  they  are  nearly  ver- 
tical, and  at  the  depth  of  225  feet,  to  which  the  mine  was  worked,  showed  no 
signs  of  closing  up.  The  ores  at  first  were  exclusively  calamine  and  smith- 
sonite  ;  but  at  greater  depth  blende  made  its  appearance,  coating  the  walls 
of  the  crevices,  and  in  some  cases  penetrating  into  them  several  feet ;  in 
other  cases,  segregated  as  rich  seams,  which  nearly  filled  the  cross-openings. 
At  first,  it  was  confined  to  the  northeastern  end  of  the  mine;  but  at  the  low- 
est depth  reached  it  could  be  traced  almost  continuously  to  the  extreme 
southwestern  end.  The  dip  of  the  ore  body  appeared  to  be  regular,  and  to 
the  southwest.  Six  of  these  parallel  crevices  were  worked,  and  about  as 
many  crossings ;  and  where  they  intersected,  rich  bunches  of  ore  were 
found,  some  of  which  were  as  much  as  60  feet  across  and  20  feet  thick.  All 
the  indications  seemed  to  point  with  increasing  certainty  to  the  existence  of 
a  backbone  or  underlying  deposit  of  blende,  out  of  the  reach  of  the  action  of 
meteoric  waters,  from  the  continuation  of  which  the  oxidized  ores  have  been 
derived. 

Timbering  the  mine  was  always  a  serious  difficulty,  but  the  greatest  ob- 
stacle to  be  overcome  was  the  water.  Even  at  a  depth  of  40  feet,  the  flow 


440  GEOLOGICAL   SURVEY    OF   PENNSYLVANIA. 

Bamford  zinc  'mines  in  Lancaster  County. 

In  the  northern  part  of  East  Hempfield  township,  Lan- 
caster county,  limestone  beds  impregnated  with  almost  in- 

was  already  very  strong  ;  at  the  depth  of  150  feet,  it  was  found  necessary  to 
put  in  what  was  then  the  largest  pumping  engine  in  the  world.  This  en- 
gine, which  is  a  single  cylinder,  double-acting,  condensing,  walking-beam 
engine,  with  a  pair  of  fly  wheels,  has  a  110-inch  cylinder  and  a  10-foot  stroke, 
and  is  calculated  to  work  four  30-inch  plunger  pumps  and  four  30-inch  lift 
pumps,  with  10-foot  stroke,  and  to  take  water  from  a  depth  of  30  feet.  At 
the  time  it  was  stopped,  it  was  running  from  six  to  seven  strokes  a  minute, 
and  was  working  three  pairs  of  30-inch  pumps  and  one  pair  of  22-inch  pumps, 
and  was  easily  handling  all  the  water  that  came  to  them.  The  pump-shaft 
and  foundation  for  the  engine  were  no  less  remarkable  in  their  way.  The 
latter  was  built  up  from  the  solid  rock,  60  feet  below  the  surface  of  the 
ground,  of  hewn  blocks  of  Potsdam  sandstone  ;  the  former,  which  measured 
30  feet  by  20  feet  in  the  clear,  was  started  on  a  small  crevice,  and  timbered 
with  12-inch  square  yellow  pine  sticks,  and  divided  into  three  compart- 
ments, and  further  strengthened  by  two  open  brattices  of  the  same  heavy 
timber.  When  the  pitch  of  the  vein  carried  it  out  of  the  shaft,  the  rest  of  the 
depth  was  sunk  through  solid  rock. 

The  Hartman  mine  distant  about  half  a  mile,  was  worked  at  first  ex- 
clusively for  calamine.  Its  exploitation  gradually  exposed  a  central  horse 
of  blende,  which  the  method  of  mining  adopted  made  it  necessary  to  leave 
for  the  support  of  the  timbers  which  carried  the  roof.  The  increasing  im- 
portance of  this  blende  at  the  lowest  level  worked,  150  feet,  caused  a  change 
to  be  made  in  the  method  of  mining.  The  mine  was  operated  for  a  year 
after  the  large  engine  was  stopped,  and  the  last  work  that  was  done  was  the 
putting  in  of  a  slope  to  develop  this  deposit  of  blende.  The  water  in  the 
Hartman  was  always  less  strong,  the  pitch  of  the  crevices  less  steep,  and 
the  surrounding  rock  less  disturbed  than  in  the  Ueberoth  mine  ;  the  strike 
of  the  crevices  was  more  to  the  west,  and  the  blende  came  nearer  to  the  sur- 
face. 

The  Saucon  mine,  however,  affords  the  simplest  and  best  illustration  of 
this  form  of  deposit.  It  is  distant  about  a  quarter  of  a  mile,  and  was  origi- 
nally leased  by  the  Passaic  Zinc  Company,  by  whom  it  was  sub-let  to  the 
Lehigh  Zinc  Company  on  high  royalties.  When  the  rich  deposit  of  calamine 
first  discovered  was  apparently  exhausted,  this  sub-lease  was  surrendered 
by  the  latter  company,  and  in  1875  the  original  lease  passed  to  the  Bergen 
Point  Zinc  Company,  by  whom  the  mine  has  been  worked  ever  since.  A 
face  of  blende  was  uncovered  at  the  western  extremity  of  the  open  pit,  and 
the  ore  followed  under  a  heavy  cap  of  limestone  for  a  distance  of  250  feet 
up  to  the  property  of  the  Lehigh  Zinc  Company  on  the  west.  On  this  pro- 
perty, it  was  reached  at  a  depth  of  110  feet,  under  100  feet  of  solid  limestone, 
and  was  followed  150  feet  farther  on  the  course  of  its  strike.  On  both  pro- 
perties, it  was  followed  to  a  depth  of  nearly  200  feet.  In  the  fall  of  1879,  all 
the  property  of  the  Lehigh  Zinc  Company  passed  into  the  hands  of  its  bond- 
holders under  foreclosure  of  its  mortgages,  and  in  the  spring  of  1880  all  the 
mining  property  was  sold  to  the  proprietors  of  the  Bergen  Point  Zinc 
Works. 

The  workings  of  these  two  mines,  taken  together,  show  a  remarkable 


ZINC   MINES   IN   NO.    II.  441 

visible  zinc  blende,  dipping  about  70°,  N.  15°  W.  at  the 
surface  and  S.  15°  E.  in  the  deep,  are  described  in  Dr. 

regularity  of  width,  pitch  and  course,  and  the  deposit  is  clearly  shown  to 
be  a  large  chimney  or  chute  of  ore  of  irregular  cross-section,  which,  how- 
ever, preserves  a  lenticular  shape,  the  longer  axis  of  which  is  about  60  feet, 
and  pitches  to  the  south  at  an  angle  of  about  30  degrees  ;  the  transverse  axis 
measures  about  30  feet.  The  axis  of  the  ore-body  dips  to  the  west-south- 
west with  a  slope  of  about  one  foot  in  four.  The  weathered  outcrop  has 
evidently  given  rise  to  the  pit  of  oxidized  ores  ana  to  certain  irregular  de- 
tached deposits  which  lie  in  the  same  course,  several  hundred  yards  beyond  it. 

Here,  then,  are  three  similar  deposits  of  zinc  ore,  with  their  nearly  parallel 
chimneys  of  blende  and  their  corresponding  beds  of  calamine,  which  have 
evidently  been  brought  up  from  below,  by  solution  in  thermal  springs, 
through  crevices  formed  in  the  limestone  by  the  gradual  upheaval  of  the 
neighboring  South  Mountain,  and  have  undergone  subsequent  alteration 
from  the  action  of  meteoric  waters.  Nearer  the  mountain,  where  tbe  strata 
are  most  tilted  and  the  ground  most  disturbed,  the  water  is  strongest  and 
the  largest  deposit  of  calamine  is  found.  In  the  Hartman  mine,  the  strata 
are  more  nearly  flat,  the  blende  is  sooner  met  with,  and  the  water  is  much 
less  strong ;  and  in  the  Saucon  mine,  the  blende  is  met  with  at  the  edge  of 
the  pit,  and  only  moderate-sized  pumps  are  required  in  working  it  at  a  depth 
of  200  feet  That  the  water  in  these  mines  comes  from  the  same  surface 
springs  which  supply  the  Saucon  Creek,  is  evident  from  the  fact  that,  when 
the  big  mine  was  abandoned,  this  creek  shrank  at  once  to  a  small  fraction 
of  its  former  volume,  and  only  gradually  recovered  it  as  the  mine  filled  up. 
Very  careful  surveys  of  the  bed  of  this  stream  failed  to  discover  any  point 
at  which  it  showed  any  diminution  of  its  volume  or  seemed  to  sink  into  the 
ground.  It  is,  therefore,  very  improbable  that  the  water,  having  once  come 
to  the  surface,  found  its  way  back  into  the  mine.  It  was  probably  tapped  in 
under-ground  courses  connected  with  the  springs  which  give  rise  to  thecreek. 
This  is  the  more  probable,  as  the  mine  which  has  the  most  water  is  on  the 
highest  ground  and  is  farthest  from  the  creek,  and  the  mine  having  the  least 
water  is  nearest  the  creek.  It  is  therefore  reasonable  to  suppose  that  nearly 
the  maximum  quantity  of  water  likely  to  be  encountered  was  already 
handled,  and  that,  if  a  solid  body  of  underlying  blende  were  developed,  it 
could  be  profitably  worked  with  the  machinery  already  in  place.  The 
Saucon  mine  is  still  the  main  dependence  of  the  Bergen  Point  Zinc  Works, 
but  its  continued  working  must  be  attended  with  increasing  cost  and  uncer- 
tain risks. 

The  ores  of  this  region  are  remarkably  free  from  lead,  arsenic  and  antimony, 
and  it  is  this  circumstance  that  gives  them  their  principal  value  and  interest, 
and  has  been  the  basis  of  the  very  high  reputation  of  the  metal  and  oxide 
obtained  from  them.  Only  the  richest  of  the  ores  are,  in  the  present  state 
of  the  ore  market,  available  as  spelter  ores,  but  even  the  leanest  of  the 
oxidized  ores  produce  a  very  fine  quality  of  oxide.  The  blende  is  very 
peculiar.  It  is  massive,  and  rarely  shows  even  traces  of  crystallization  ; 
when  pure,  it  has  a  bluish  slate  color,  has  a  very  characteristic  conchoidal 
fracture,  is  translucent  on  thin  edges,  and  gives  a  clear  ring  when  struck. 
As  generally  sent  to  the  works,  it  resembles  broken  limestone ;  is  somewhat 
mixed  with  iron  pyrites,  and  assays  from  35  to  40  per  cent  of  zinc.  It  is  not 


442  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

Frazer's  Report  C3,  p.  55  At  the  west  end  of  open  cut 
No.  1,  a  shaft  was  sunk  cutting  two  or  three  belts  rich  in 

easy  to  concentrate,  both  on  account  of  its  non-crystalline  structure  and  of 
the  pyrite  it  contains. 

The  causes  which  led  to  the  extinction  of  the  Lehigh  Zinc  Company  and 
the  abandonment  of  the  first  two-named  mines  were  briefly  these  ;  the  im- 
possibility of  competing  successfully  in  the  oxide  market  with  the  owners 
of  the  big  mine  in  Sussex  county,  New  Jersey,  after  the  expiration  of  the 
patents  covering  the  oxide  process  left  them  free  to  take  the  trade,  or  in  the 
sheet-zinc  and  metal  market  with  the  Western  smelters,  using  cheaper  and 
richer  ores,  at  a  time  when  a  general  depression. of  all  manufacturing  enter- 
prises made  it  unusually  burdensome  to  carry  the  heavy  bonded  indebted- 
ness incurred  during  a  period  of  high  prices  and  general  inflation  in  acquir- 
ing mines  and  putting  up  machinery  to  work  them.  Under  more  favorable 
circumstances,  it  is  probable  that  these  mines  could  have  been  profitably 
worked  for  years  to  come  ;  for  although  the  pumping  expenses  were  heavy> 
they  were  not  excessive,  considered  as  a  royalty  on  the  ore,  and  these 
charges  per  ton  would  diminish  in  proportion  to  the  amount  of  ore  mined. 
Now,  however,  it  will  probably  be  left  for  another  generation  to  discover 
what  value  they  still  have. 

Other  deposits  of  zinc  ore  have  been  discovered  in  the  same  Silurian  for- 
mation in  Pennsylvania,  Maryland  and  Virginia,  which  have  been  worked 
from  time  to  time,  but  have  produced  very  inconsiderable  amounts  of  ore. 
Small  oxide  works  were  built  at  an  early  day  near  Birmingham,  Blair 
county,  and  at  Landis  station,  in  Lancaster  county,  Pennsylvania,  but  they 
were  soon  abandoned.  At  the  latter  point,  shallow  beds  of  rich  carbonate 
of  zinc  were  first  discovered,  but  were  worked  out.  About  1876,  expensive 
concentrating  works  and  two  blocks  of  spelter-furnaces  were  put  up,  to 
treat  the  grains  and  kernels  of  c^stallized  blende  scattered  through  the 
underlying  limestone,  before  sufficient  exploration  was  made  to  warrant 
such  an  outlay  of  money  ;  they  have  for  years  been  lying  idle. 

Mr.  J.  Eyerman,  furnished  the  same  journal  December  15,  1883,  the  follow- 
ing interesting  particulars: — As  the  ore  (calamine,smithsonite  and  sphalerite) 
in  this  mine  is  near  the  surface,  it  is  not,  at  present,  difficult  to  work.  The 
calarnine  is  found  in  large  quantities  disseminated  through  the  limestone. 
It  is  found  mostly  on  the  north  side  of  the  mine,  where  it  is  worked  by  a 
small  force  of  men. 

This  mine  has  furnished,  and  will  continue  to  furnish,  the  finest  speci- 
mens of  calamine  (or  silicate  of  zinc)  known  to  the  world.  It  is  very  often 
found  in  botryoidal  and  stalactical  forms.  It  is  not  seldom  that  sheets  or 
plates  of  calamine  from  two  to  three  feet  square  and  from  one-eighth  to  one- 
fourth  of  an  inch  thick,  and  containing  thousands  of  little  crystals  on  the 
surface,  are  found  between  the  crevices  of  the  limestone.  Again,  it  is  found 
as  a  thin  coating  to  the  inside  of  a  quartz  geode.  This  ore  is  quite  scarce  at 
the  Endy  mine.  It  seems  to  have  been  replaced  by  the  blende.  The  smith- 
sonite  or  carbonate  of  zinc  is  found  in  white  scales  and  in  granular  masses, 
coating  calamineand  blende.  It  is  also  more  commonly  found  as  a  brownish 
earth,  which  hardens  when  dry.  It  is  found  near  the  center  and  along  the 
west  side  of  the  mine.  It  has  often  been  mistaken  for  clay.  This  is  also 
mined  at  present  by  a  small  number  of  men.  The  sphalerite  or  zinc-blende 


ZINC   MINES    IN   NO.    II.  443 

zinc.  The  east  end  of  cut  No.  2  showed  the  vein  striking 
N.  85°  E.  In  a  small  open  cut  £  m.  W.  of  RR.  bridge  over 
Little  Conestoga  creek  80  tons  of  sandy  limestone  impreg- 
nated with  calamineand  blende,  and  seamed  with  calcite, 
were  taken  out ;  dip  apparently  50°,  N.  10°  E. ;  but  on  the 
RR.  the  limestones  dip  8°,  N.  5°  W. 

The  Bamford  mine  was  worked  for  a  white  oxide  between 
1850  and  1860.  Streaks  of  silver  lead  are  found  in  the  lime- 
stone, which  is  about  12'  thick.* 

Mr.  E.  G.  Spilsbury's  letter  respecting  the  mine  (C3,  p. 
198)  describes  two  parallel  beds  of  the  limestone,  near  the 
slate,  but  not  at  the  contact  of  the  two  formations,  as  in 
Blair  county,  "  unmistakably  bedded  veins,  and  not  fissure 
or  gash  veins  ;  conformable  both  to  the  stratification  and 
dip  of  the  inclosing  rocks  ;  "  striking  N.  74£°  E.  and  dip- 
ping 72°,  N.  15i°  W. 

The  hanging  wall  limestone  is  a  breccia  (or  crushed)  par- 
tially decomposed,  whitish  gray,  and  highly  silicious  ;  full 
of  seams,  cavities,  and  small  caves  (15'  to  20'  long  and  as 
many  broad,  by  4'  to  6'  high),  all  completely  filled  with  a 
dark  red  sandy  loam,  and  not  with  mineral  as  in  Missouri 
and  Illinois.  In  none  of  these  loam-filled  "cavities  have  I 
ever  found  a  trace  of  mineral."  The  broken  condition  of 
the  roof  limestone  extends  from  the  surface  to  the  bottom 
of  the  pump  shaft  110'.  The  foot  wall  is  not  uniformly 
smooth  but  has  offsets,  like  layers,  shelving  downward  over 
and  past  each  other  and  into  the  ore  body  ;  or,  in  other  words, 
the  ore  passes  up  between  these  shelving  layers  of  dark 
blue  limestone  sometimes  to  a  distance  of  8  or  10  feet.  (See 
figure  in  C3,  p.  199.)  The  foot  wall  limestone  is  less  silici- 
ous, dark  blue,  in  places  almost  black,  and  very  close  and 

is  not  mined.  It  is  found  throughout  the  mine,  with  pyrite  disseminated 
through  it.  It  is  not  met  with  in  as  large  quantities  here  as  at  the  Endy 
mine.  Greenockite  (sulphide  of  cadmium),  hydrozincite,  and  goslarite 
(sulphate  of  zinc)  are  met  with  in  smaller  quantities.  The  sulphate  of  zinc 
is  scarcely  ever  found.  A  considerable  quantity  of  greenockite  has  been 
mined.  It  is  found  as  a  yellowish  powder  coating  blende  and  limestone. 
It  was  formerly  separated  at  the  LJethlehem  works. 

*  Notes  by  P.  Frazer,  July,  1876,  C3,  p.  196,  give  details  of  crushing  and 
roasting. 


444  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

compact,  with  occasionally  small  holes  lined  with  ealcspar 
and  frequently  filled  with  specular  iron  ore. 

The  minerals  in  the  vein  matter  consists  of  the  two  sul- 
phides of  zinc  and  lead  ;  changed  for  about  18'  beneath  the 
surface  to  calamine  and  carbonate  of  lead  ;  unchanged  sul- 
phides below.  The  vein  matter  or  gangue  itself  is  a  lime- 
stone very  like  that  of  the  foot  wall,  but  crystalline  in 
spots.  The  galena  (sulp.  lead)  is  found  in  bunches  or  little 
strings  running  along  on  or  near  the  hanging  wall ;  but  the 
Jjlende  (sulp.  zinc)  impregnates  the  whole  vein  matter,  more 
or  less  thoroughly. 

The  percentage  of  silver  in  the  galena  varies  wonderfully 
from  $2  per  ton  in  one  bunch  to  $2,000  in  the  bunch  next 
to  it ;  a  general  average  may  be  perhaps  $22.* 

Sinking  Valley  zinc  and  lead  mines  in  Blair  county. 

These  are  described  by  Mr.  F.  Platt  in  chapter  XV  of  his 
Report  on  Blair  county,  T,  1881,  pages  247  to  277,  only  a 
short  summary  of  which  can  be  given  here,  the  reader 
being  referred  to  the  original  report. 

Sinking  valley  is  the  triangular  south  end  of  Nittany 
valley,  south  of  the  Little  Juniata  river ;  10  miles  long  by 
5  wide  at  the  river ;  anticlinal  in  structure,  the  axis  sinking 
southward,  as  shown  by  Figs.  33  and  and  34.f  The  lime- 
stones dip  about  30°,  S.  E.  on  the  east  side  of  the  axis,  and 

*The  bright  golden  "rosin  blende"  is  very  pure;  only  slight  traces  oi 
iron  and  cadmium,  and  a  small  mechanical  admixture  of  lead ;  average  of 
14  samples:  zinc,  65.9;  sulphur,  32.3 ;  iron,  0.8;  lead,  0.3;  cadmium,  0.07. 
Average  of  a  year's  work  showed  about  18  per  cent,  of  blende  in  the  vein. 
Run  of  vein  one  mile;  another,  covered  with  15'  soil,  1|  m.  further  on. 
reins  proved  to  depths  of  75'  and  110'.  North  vein' worked  out  for  300',  to 
a  depth  of  50',  with  an  average  width  of  12'.  South  vein  worked  out  400',  to 
a  depth  of  75' ;  more  regular  ;  width  from  14'  to  18'  ;  zinc  in  vein  never  ex- 
ceeded 12  p.  c.;  richest  ore  from  50'  down  to  75' ;  "at  the  110'  level,  although 
the  vein  is  well  defined,  there  is  little  or  no  ore  in  it,  at  any  of  the  points 
where  it  has  been  opened,  and  what  little  ore  is  in  it  appears  in  strings  and 
not  disseminated  as  above."  (For  details  of  history,  machinery,  cost  of 
mining,  manufacture  of  spelter,  &c.,  see  Mr.  Spilsbury's  letter  in  C3,  pp. 
202,  203.) 

fThe  axis  sinks  at  the  rate  of  600'  per  mile  from  the  vein  at  Birmingham 
to  the  head  of  the  Kettle;  so  that  the  zinc  mines  are  very  low  down  in  the 
magnesian  limestones  of  II. 


ZINC   MINES   IN   NO.    II.  445 

about  80°  E.  S.  E.  (overturned),  on  its  west  side.  The 
Keystone  Zinc  Co.'s  mine  near  Mr.  Kinch's  house,  and  the 
deep  shaft  on  the  Borie  farm  are  both  near  the  axis. 

Fissure  veins  occur  in  various  parts  of  the  valley,  and 
were  tried  for  as  long  ago  as  the  War  of  Independence,  as 
the  old  pits  on  the  Fleck  farm  bear  witness.*  But  most  of 
the  work  has  been  done  by  the  Keystone  Zinc  Co.,  which 
was  incorporated  in  1864,  and  abandoned  mining  in  1870.  In 
1875  the  Tathams  tried  to  find  good  working  ore  with  a  deep 
diamond  drill  hole  east  of  the  Fleck  farm.  In  1876  W. 
Arms  tried  to  develop  a  vein  on  the  Isett  farm.  Still  later 
prospecting  has  been  done,  and  the  citizens  of  that  district 
are  subject  to  periodical  excitements  by  vague  or  incorrect 
reports  of  mineral  wealth  hitherto  concealed,  or  "never 
properly  developed,"  as  the  favorite  phrase  is  worded.  But 
certainly  enough  has  been  done  to  disprove  the  probability 
of  extensive  deposits  underground,  and  to  sustain  the  geo- 
logical theory  that  the  metals  were  originally  distributed 
through  the  limestone  strata,  set  free  by  erosion,  and  con- 
centrated in  small  quantities  in  fissures. 

It  is  impossible  to  examine  the  closed  up  and  decayed 
workings ;  but  much  can  be  learned  from  the  reports  of  ex- 
perts like  Dr.  Roepper  of  Bethlehem  ;  Mr.  Williams  of 
Philadelphia  ;  Mr.  IHckerson,  Mr.  Spilsbury  and  others.f 

The  Keystone  Zinc  Co.'s  shafts,  about  \  m.  S.  W.  of  Bir- 
mingham, were  sunk  from  the  top  of  a  knoll  80'  above  the 
road,  and  drained  by  an  adit  level,  driven  on  347'  S.  W. 
One  line  of  shafts  followed  the  limestone  strike  on  a  vein 
so  variable  as  to  open  out  into  spacious  chambers,  and  con- 
tracting again  to  a  mere  crack.  This  fact  alone  suffices  to 
stamp  the  "  vein  "  as  no  true  vein,  but  a  cavern  deposit,  like 
any  limonite  bed.  Were  there  a  true  vein  it  might  be 
traced  to  the  river  and  be  found  in  the  bank  ;  but  no  trace 
of  ore  has  rewarded  diligent  search  in  that  direction,  and 

*SeeGen.  Roberdean's  letter  to  President  Reed,  dated  April  17,  1778,  in 
Pennsylvania  Archives,  Vol.  6,  p.  422.  Smelted  lead  was  sent  down  the 
river  in  flat  boats.  Another  attempt  was  made  by  John  Musser  <fe  Robert 
Morris  in  1795,  the  probable  date  of  the  old  tunnel  on  the  Keystone  Zinc 
€o.'sland. 

t  Mr.  Platt  had  access  to  these  reports,  most  of  them  in  manuscript. 


446  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

no  success  has  rewarded  equally  diligent  research  in  the 
other  direction,  south  west  ward.* 

The  zinc  blende  and.  galena  are  combined  in  compact,  fine- 
grained, dark  (waxy  when  broken)  lumps,  some  as  large  as 
a  man's  head.  The  sulphide  of  lead  is  always  present,  but 
always  subordinate  to  the  sulphide  of  zinc  ;  there  is  usually 
a  little  calamine  (hydrous  silicate  of  zinc) ;  and  the  gangue 
is  inconsiderable,  consisting  of  magnesian  limestone  and  a 
little  iron  py  rites,  f 

At  the  southwest  end  of  the  valley,  therefore  in  the 
upper  limestones  of  II,  the  zinc-lead  deposits  differ  from 
those  near  Birmingham.  Here  the  fissures  run  transverse 
to  the  strike  of  the  limestones,  are  nearly  vertical,  and  few 
of  them  more  than  6  inches  wide.  Frequently,  but  not 
always,  a  thin  coating  of  heavy  spar  (sulpJiate  of  baryta) 
separates  the  ore  from  the  limestone  walls  ;  and  much  heavy 
spar  is  associated  with  the  blende  and  galena  in  the  gangue 
stuff.:}: 

*It  must  be  said  that  no  continuous  trench  along  the  outcrop  of  the  sup- 
posed vein  was  ever  made  ;  and  its  alleged  continuity  was  considered  to  be 
proved  by  a  gangway  166'  long,  connecting  two  shafts  below.  More  than 
2000  tons  were  won  from  the  shafts ;  one  yielding  very  lean  ore,  the  others 
very  rich  ore.  What  remains  unsmeltea  at  the  abandoned  works  at  Bir- 
mingham is  ore  of  even  quality,  analyzing  up  to  a  maximum  of  30  per  cent 
metallic  zinc. 

f  Analysis  by  McCreath  :  Sulp.  lead,  18.37  ;  sulp.  zinc,  76.98 ;  ox.  iron  and 
alum.,  1.90;  carb.  lime,  0.05;  carb.  mag.,  0.17  ;  water,  0.27;  silica,  1.67  ;  that 
is  lead  15.91  ;  zinc  51.63.  Another  specimen  yields  lead,  5.86  ;  zinc,  30.40.— 
For  Mr.  Williams'  description  of  the  seven  shafts  and  workings,  see  T,  p. 
258,  etc.  He  says  that  shafts  5,  6,  7  had  been  (Nov.,  1865)  carried  down 
through  a  heavy  mass  of  ore  and  connected  by  a  165'  long  drift  all  in  the 
same  mass,  with  an  average  thickness  of  7';  quality  excellent.  He  esti- 
mated that  there  had  been  an  output  of  1300  tons  of  rock  ore  (30  p.  c.)  and 
2000 tons  of  "wash  or  earthy"  ore  (8  p.  c.).  He  remarks  that  the  dolomite 
wall  rock  was  singularly  tree  from  impregnate  particles  of  blende  or  galena  ; 
one  specimen  analyzing  carb.  lime,  53.9  ;  carb.  mag.,  41.3.  But  Platt  re- 
marks that  there  was  abundant  evidence  that  thin  streaks  and  threads  of 
both  ores  do  occur  in  the  dolomite  rocks.  On  the  Kinch  farm,  directly  oppo- 
site the  company's  adit,  runs  a  sandy  limestone,  through  which  much  galena, 
blende  and  calamine  are  scattered  but  too  sparingly  to  make  the  rock  an 
ore  (T,  p.  262).  This  outcrop  is  continuous  for  a  long  distance  without 
changing  its  character.  The  presence  of  calamine  shows  that  the  sulphides 
have  been  reached  and  converted  by  percolating  waters. 

{See  description  and  analysis  in  T,  pp.  263,  264.  The  pits  on  the  McMullen 
farm,  are  close  to  the  edge  of  the  slate  belt,  No.  III.  The  Kryder  pits  are 


ZINC    MINES    IN   NO.    II.  447 

All  that  lias  been  said  above  proves  that  these  zinc-lead 
veins  are  precipitation  deposits,  are  not  connected  with  any 
deep  metallic  masses  in  the  under  world,  and  cannot  de- 
scend lower  than  the  extreme  limit  of  rain  water  percola- 
tion in  any  district  of  the  State  to  which  they  belong.  I  can- 
not agree  with  Dr.  Roepper*  in  looking  upon  them  as  true 
veins,  afterwards  distorted  by  a  fault-slide  pressure  into 
chimneys  and  pockets  like  the  magnetic  iron  ore  veins  (or 
beds)  of  northern  New  Jersey  with  which  he  was  so  well 
acquainted.  I  consider  them  as  of  the  nature  of  compara- 
tive recent  cavern  and  fissure  deposits,  scarcely  at  all 
changed  in  form  by  later  earth  movements. 

Barytes  in  II. 

Barytes  (sulphate  of  baryta}  occurs  rather  frequently 
in  small  pockets  in  the  limestones  of  II  (as  well  as  in  the 
«Lower  Helderberg  limestones  of  VI)  usually  accompanied 
by  small  percentages  of  sulphate  of  stronlia ;  but  strange 

not  far  off.  The  Bridenbaugh's  pits  and  cross  cuts  revealed  one  vein  8  in. 
wide  with  N.  W.-S.  E.  strike,  vertical  and  unchanged  to  a  depth  of  25',  with 
abundance  of  heavy  spar.  On  the  Raemy  farm  much  scattered  surface  ore. 
The  Crissman  pits  proved  three  fissure  veins,  ono  said  by  Mr.  Dickerson  to 
be  fifteen  inches,  thickening  downward ;  another  3  feet  wide,  and  forking 
and  reuniting  around  a  wall  horse.  Of  these  shafts  Mr.  Williams  afterwards 
expressed  an  unfavorable  opinion.  The  Borie  farm  "deep  shaft"  (80')  was 
sunk  on  a  4-inch  vein,  thickening  downwards  to  14  inches,  yielding  300  tons 
and  then  abandoned.  The  Fleck  farm  pits  showed  other  fissure  veins,  in 
which  the  gangue  is  between  rock  walls,  both  of  them  lined  with  calcspar. 
The  Isett  farm  shafts  are  said  to  have  been  sunk  on  two  parallel  veins,  each 
nearly  2'  wide,  and  striking  with  the  country  rock.  (T,  p.  271.) 

*  "The  fact  that  the  ores  are  mainly  sulphides,  and  placed  in  rock  almost 
entirely  unaccompanied  by  clay,  excludes  the  idea  of  their  being  merely 
mechanically  transported  into  already  existing  cavities  of  the  rocks.  The 
whole  mode  of  occurrence  contradicts  such  a  supposition,  and  leads,  irre- 
sistibly, to  the  conviction  that  the  ores  were  formed  in  the  place  they  are  now 
found,  by  geological-chemical  agencies  ;  that  the  pocket  shape  of  the  lodes 
is  merely  the  result  of  mechanical  derangement  and  contortion  of  the  hill ; 
and  that  these  pockets  have  been  formed  out  of  original  true  veins  following 
theoriginal  N.  E.  and  S.  W.  strike  of  the  strata.  Itisonly  necessary  to  notice 
the  shattered  condition  of  the  rock,  and  to  observe  the  contortions  exhib- 
ited by  the  section  of  the  hill  along  the  Pennsylvania  railroad,  readily  to  ac- 
count for  the  transformation  of  regular  veins  into  a  more  or  less  irregular 
system  of  pockets."  (Roepper.) 


448  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

to  say  no  trace  of  the  latter  could  be  found  in  the  five  analy- 
ses made  by  McCreath  (3  from  II,  and  2  from  VI)  published 
in  Report  M2,  p.  369. 

In  Franklin  county,  in  the  Great  Valley,  2£  m.  S.  of 
Waynesboro,  on  Chr.  Shockley's  farm,  it  was  found  in 
radiating  columnar  masses ;  white  to  bluish  white  ;  vitre- 
ous lustre  ;  (Spec.  735)  sul.  baryta,  95.91 ;  silicic  acid,  2.80  ; 
ox.  iron  and  alum.,  0.24  ;  lime,  017  ;  magnesia,  0.11 ;  water, 
0.09.  Another,  found  in  that  vicinity,  granular,  also  slightly 
fibrous,  generally  very  white,  some  stained  with  iron  oxide, 
powder  white  with  brownish  tinge  ;  sulp.  bar.,  98.05  ;  sil. 
acid,  1.11 ;  ox.  iron  and  al.,  0.  14  ;  traces  of  lime,  mag.  and 
carb.  acid  ;  water,  0.20.  It  has  been  found  as  white  lamel- 
lar barite  on  S.  Plum's  farm  in  Franklin  county.  (Genth's 
Report  B,  p.  228. ) 

In  Blair  county  at  Galbraith's  2  m.  S.  S.  W.  of  Birming- 
ham, the  analysis  being  quite  like  the  last.* 

In  Montgomery  county,  at  Marble  Hall,  a  granular  gray- 
ish-white barife  resembling  marble  occurs  with  the  marble- 
beds  of  No.  II. f 

That  bar  He  must  be  extensively  and  rather  abundantly 
distributed  through  some  if  not  all  the  formations  of  the 
State  is  proved  by  Dr.  Genth's  analysis  of  that  remarkable 
flow  of  salt  water  from  an  oil  boring  in  Elk  county,  called 
the  "  East  Clarion  Spring  Water,"  one  gallon  of  which  con- 
tained 419  grains  of  matter,  of  which  337  were  chloride  of 

*  T,  p.  246.  Two  other  quite  identical  analyses  of  the  mineral  from  the 
lower  Helderberg  limestone  (VI)  near  Fort  Littleton  in  Fulton  county,  will 
be  given  in  the  chapter  on  that  formation. — Barite  has  also  been  found  at  the 
bottom  of  VII  (Oriskany  <S&)  in  Sandy  Ridge  near  Orbisonia,  Huntingdon 
county.  (Genth's  B,  p.  228.) 

f  Barium  is  confined  to  no  formation,  but  it  affects  mines  of  limonite,  and 
is  probably  held  in  solution  by  many  of  our  waters.  Dr.  Genth  reports  it 
in  very  perfect  transparent,  greenish,  tabular  crystals  (£  in.  diameter)  and 
clusters  of  bluish  tabular  crystals;  also  crested,  fascicular,  and  radiated 
crystals  and  crystalline  masses  at  Perkiomen  mine  near  Shannon ville,  Mont- 
gomery county.  Also,  fibrous  with  copper  ore  at  Jug  Hollow  mine,  Mont- 
gomery county.  Also,  white  laminated  crystalline  masses  at  Phoanixville 
mines  ;  and  in  similar  manner  and  also  crystallized  with  copper  ores,  3  m. 
W.  of  New  Hope,  in  Bucks  county.  Also,  a  fetid  barite  in  brownish  radiat- 
ing and  columnar  ferruginous  masses  at  Heidelberg,  Berks  county.  (Re- 
port B,  p.  146.) 


ZINC    MINES   IN   NO.    II.  449 

sodium,  52  were  chloride  of  calcium,  15  chloride  of  magne- 
sium, 1.725  chloride  of  barium,  and  0.128  bicarbonate  of 
barium* 

It  is  very  surprising  that  strontium  should  not  appear 
in  company  with  barium  in  the  limestones  of  II  and  VI. 
In  the  East  Clarion  Spring  water  Dr.  Genth  only  found 
0.06  grains  of  the  chloride  and  0.005  grains  of  the  bicar- 
bonate of  strontia.  But,  on  the  other  hand,  the  sulphate 
of  strontia  (celestite)  makes  the  famous  stratified  bed  in 
Blair  county,  opposite  Bell's  Mills. f 

The  origin  of  the  barite  in  our  sedimentary  rocks  is  an 
interesting  problem.  The  masses  found  are  evidently  seg- 
regations, precipitations  from  water  confined  in  cavities, 
hut  how  localized  is  not  understood.:}: 

It  is  however  brought  into  immediate  relations  to  the 
veins  of  zinc-lead,  by  the  occurrence  of  two  true  veins  of 
sulphate  of  baryta  (heavy  spar)  in  the  hill  on  the  Kinch 
farm  in  Blair  county,  one  6  inches  and  the  other  3  inches 
wide,  separated  by  two  feet  of  sandy  limestone  (Calcifer- 
ous,  Ila)  dipping  nearly  vertical  and  striking  N.  E.-S.  W. 
These  veins  have  no  other  material ;  but  some  of  the  zinc- 
lead  veins  have  in  their  gangue  a  considerable  admixture 
of  heavy  spar.  (T,  p.  272.) 

*  He  adds  that  this  mineral  water  contains  the  largest  quantity  of  chloride 
of  barium  ever  observed  in  any  springs,  and  may  become  of  great  importance 
after  its  medicinal  properties  have  been  more  fully  investigated.  (Report  B, 
1874,  p.  27.) 

t  It  occurs  here  in  a  series  of  thin  seams,  pale  green,  crystallized  in  col- 
umns of  fibres,  crosswise,  containing  strontia  42,  sulp.  acid  58.  (Klaproth, 
1797.) — H.  C.  Lewis,  however,  found  a  white  fibrous  aragonite  in  seams 
and  crystalline  crusts  in  the  nearly  pure  limestone  of  the  Water-lime  divi- 
sion of  formation  VI  in  Mifflin  county,  opposite  Mt.  Union,  2  in.  E.  of  Ma- 
tilda furnace,  containing  carb.  strontia  0.58  ;  and  with  this  Dr.  Genth  found 
groups  of  minute  divergent  needles  of  strontianite,  consisting  of  carb.  lime 
15.36,  carb.  strontia  83.15,  etc.  (Report  B,  1876,  p.  229.) 

f  Dr.  Genth's  analysis  of  the  green  orthoclase  felspar  lennilite  (or  dela- 
warite)  of  Delaware  county,  gave  0.57  baryta ;  and  his  three  analyses  of 
another  orthoclase  felspar  (Lea's  cassinite)  from  Blue  Hill,  Delaware 
county,  gave  3.79,  3.75,  3.60  baryta.  The  clays  produced  by  the  decomposi- 
tion of  such  felspars  must  necessarily  retain  much  barita  converted  into 
barite. 


29 


450  GEOLOGICAL   SURVEY   Of   PENNSYLVANIA.. 

Gypsum  absent  from  No.  II. 

Plaster  rock  (gypsum,  sulphate  of  lime}  does  not  occur 
in  formation  II  in  Pennsylvania.  In  fact  even  as  isolated 
crystals  it  is  extremely  rare  in  the  State,  and  is  only  seen 
where  the  water  from  oxydized  pyrites  acts  on  the  lime- 
stone beds,  as  at  Van  Arsdale's  quarry  near  Feisterville, 
Bucks  county,  producing  beautiful  slender  crystals,  some- 
times 2  in.  long  and  £  in.  wide,  or  much  smaller  as  at  Corn- 
wall. Such  needles  frequently  are  seen  on  the  magnetic 
iron  ore,  or  upon  a  decomposed  clay-like  mineral,  often  in- 
termixed with  arborescent  copper.  (Genth  in  B,  p.  148.) 

The  so  called  "Plaster  rock"  of  the  Wilsham  quarry  in 
Nippenose  valley  on  the  Clinton  county  line,  ground  at 
Metzger's  and  other  plaster  mills  near  by,  and  sold  as  plaster 
at  prices  little  below  Cayuga  or  Nova  Scotia  plaster,  was 
found  by  McCreath,  at  the  Survey  Laboratory  in  Harris- 
burg,  to  be  a  nearly  pure  limestone,  with  less  than  1  per 
cent,  of  gypsum  in  it.* — The  place  of  the  beds  is  about 
500'  beneath  the  bottom  of  the  slate  formation  No.  III. 

*  Montreal  plaster  has  sulp.  acid  46,  lime  33,  water  20.  The  Nippenose 
plaster  consists  of  carb.  lime  95.1 ;  carb.  magnesia  1.0  ;  silica  2.7  ;  sulp.  lime 
(gpysum)  0.7 ;  carb.  iron  0.3  ;  carbon  and  water  0.2.  (Report  G2,  p.  81.) 


TRAP   DYKES   IN  NO.    II.  451 


CHARTER  XXXVIII. 
Trap  dykes  in  No.  II. 

In  Berks  county,  a  trap  dyke,  4m.  W.  of  Reading,  issues 
from  the  Trias  country  and  cuts  the  limestone  belt  in  a  IS. 
E.  direction.  Crossing  the  turnpike  a  little  E.  of  Sinking 
Springs  and  following  down  the  west  side  of  Cacoosing 
creek,  it  makes  a  fine  show  on  Tulpehocken  creek  near  Van 
Reed's  mill.  Its  boulders  appear  on  the  slate  soil  further 
on  near  Epler's  ;  but  the  dyke  cannot  be  traced  beyond 
this  to  the  Schuylkill.* — It  is  evident  that  this  dyke  is  in 
some  way  connected  with  the  great  outbursts  of  trap  in  the 
Trias  south  of  Fritztown  near  the  Lancaster  county  line  ; 
but  the  long  way  it  runs,  its  straight  course,  and  its  nar- 
rowness make  it  difficult  to  suppose  that  the  crack  was  in- 
vaded horizontally.  The  lava  must  have  come  from  a  great 
depth,  and  therefore  could  have  had  no  real  connection  with 
the  Trias.  Its  abundance  in  the  Trias  only  goes  to  show 
that  the  disturbance  which  produced  the  fractures,  and  the 
filling  of  these  cracks  with  lava,  were  events  of  a  post- 
triassic  age. — A  similar  occurrence  on  a  much  larger  scale 
in  Cumberland  county  teaches  the  same  lesson. 

In  Lebanon  county  a  small  dyke  issues  from  the  edge  of 
the  Trias  2m.  E.  of  Campbellstown,  just  west  of  Killingers 
run  and  can  be  followed  half  a  mile  across  the  limestone. 

But  N.  of  Lebanon  city  is  a  much  more  remarkable  case. 
Three  dykes  appear  between  Mt.  Ararat  and  Jonestown, 
running  in  parallel  E.  and  W.  lines,  about  a  mile  apart ; 
the  middle  one,  about  4  miles  long,  reaching  nearly  to  Mt. 
Union  P.  O.  They  are  in  the  slate  belt.  They  do  not 
touch  the  limestone  belt ;  nor  run  ~N.  and  S.  as  if  connected 
with  the  reservoirs  of  trap  under  the  Lancaster-Lebanon 

*  Rogers'  Geol.  Pa.,  1858,  p.  251.  It  has  been  omitted  accidentally  from  the 
Berks  county  map  in  Hand  Atlas,  X. 


452  GEOLOGICAL   SURVEY   OP   PENNSYLVANIA. 

county  line.  They  must  certainly  come  up  from  the  azoic 
floor  beneath  the  limestone  which  is  beneath  the  slate  ;  that 
means  from  a  depth  of  at  least  a  mile  beneath  the  present 
surface.* 

In  Montgomery  county  a  long  staight  trap  dyke  crosses 
the  Schuylkill  river  at  Conshohocken  500'  N.  of  the  bridge, 
where  it  outcrops  on  the  west  bank  in  a  picturesque  black 
wall  40'  thick  and  as  many  high.  It  runs  east  and  west 
from  the  river  in  an  almost  absolutely  straight  line  (about 
N.  23°  E.)  eight  miles,  from  the  Chester  county  line  a  mile 
W.  of  Mechanicsville,  toFlourtown,  east  of  which  it  cannot 
be  traced  continuously,  if  at  all,  into  the  Trias  country 
towards  Doylestown.f 

For  2^  miles  west  of  the  Schuylkill  it  runs  through  South 
Valley  Hill  primal  slates,  which  stand  like  the  dyke  nearly 
vertical.  A  mile  east  of  the  river  it  takes  the  line  of  contact 
of  slate  and  limestone,  and  keeps  it  two  miles  further  to 
Marble  Hall ;  for  the  next  mile  it  runs  obscurely  in  the 
limestone ;  for  the  next  two  miles  it  is  plainly  seen  in  the 
heart  of  the  limestone  belt  crossing  its  center  line  very 
obliquely  to  Flowertown.  It  nowhere  indicates  disturb- 
ance or  faulting  of  the  formations  up  through  which  it 
comes  from  some  unknown  depth,  where  an  unexplained 
reservoir  has  furnished  all  the  dolerite  traps  of  the  region, 
for  they  are  all  alike,  whether  they  cut  gneiss,  primal  slate, 
limestone,  or  Trias.:}: 

*  These  dykes  are  represented  cm  the  small  colored  map  of  Dauphin  and 
Lebanon,  No.  22  of  the  Hand  Atlas,  Report  X,  as  located  by  Mr.  Sanders  in 
his  survey  of  the  slate  belt.  The  presence  of  trap  is  well  known  to  the  citi- 
zens of  Lebanon.  Whether  the  crushed  limestone  breccias  of  Mt  Ararat 
were  made  during  the  movements  connected  with  this  eruption  of  lava,  no 
doubt  in  Pofct-triassic  times,  is  a  mere  conjecture. 

|  Prof.  H.  C.  Lewis  thought  he  could  make  it  continuous  that  far.  Mr.  C.  E. 
Hall  however  gives  on  a  page  plate  map  (Fig.  4,  p,  22,  Report  C6,  1881)  a  line 
AB  in  prolongation  of  the  dyke  eastward,  and  another  line  CD,  32°  off  to 
the  north,  passing  through  four  patches  of  trap  boulders  on  cross  roads,  and 
close  to  a  fifth  at  Jarrettown.  Mr.  B.  S.  Lyman's  survey  of  the  Trias  belt 
has  taught  that  a  connection  of  the  Conshohoken  dyke  with  the  sporadic  trap 
shows  of  the  Trias  is  improbable.  The  same  may  be  said  of  its  continuity 
westward  with  the  sporadic  traps  of  ^Delaware  and  Chester  counties. 

%  See  Dr.  F.  A.  Genth's  analyses  given  in  C6,  pp.  94  to  99,  Specs.  5063,  '4, 
501J6,  7,  '9,  5072,  5081,  '2,  '4,  '6,  and  p.  134,  Spec.  7789,  which  last  reads:  Loss 


TRAP   DYKES   IN    NO.    II.  453 

It  might  be  supposed  that  this  trap  dyke  has  had  some- 
thing to  do  with  making  the  white  marble  beds  at  Marble 
Hall,  if  that  idea  were  not  negatived  by  the  fact  that  the 
range  of  white  marble  quarries  east  and  west  of  the  Schuyl- 
kill  is  quite  independent  of  the  dyke. 

In  Lancaster  county  Prof.  Frazer  has  traced  an  extraor- 
dinary trap  dyke  from  the  Susquehanna  river  3  m.  above 
the  Maryland  State  line,  in  a  N.  E.  by  N.  nearly  straight 
course,  past  Goshen,  Quarryville  and  May  P.  O.,  Kinter's 
P.  O.,  Boyerstown,  and  Springville  (Salisbury  P.  O.),  to 
the  Welsh  Mountain  2  m.  E.  of  Mt.  Airy,  a  distance  of  25 
miles.  It  probably  passes  on  five  miles  further  concealed 
beneath  the  primal  sandstone  surface  rubbish  of  the  mount- 
ain land,  and  is  seen  again  for  2  miles  crossing  the  Cones- 
toga  valley  limestone  2  m.  W.  of  Churchtown,  then  losing 
itself  beneath  the  southern  edge  of  the  Trias,  as  if  making 
for  the  great  trap  outburst  in  Berks  county  on  the  north 
edge  of  the  Trias,  S.  and  S.  E.  of  Reading. 

At  Quarryville  it  cuts  diagonally  across  the  limestones 
of  the  Chester  valley  ;  at  Kinzer's,  Boyertown  and  Spring- 
ville it  cuts  for  6  miles  diagonally  across  the  limestones  of 
Pequea  valley  ;  at  its  south  end  it  cuts  diagonally  across 
the  Peach  Bottom  primal  slates ;  and  in  other  long 
stretches  of  its  course  it  cuts  the  Philadelphia  schists. 

At  Springville  it  is  either  interrupted  for  a  short  dis- 
tance, jogged  to  the  east,  or  is  duplicated,  the  surface  being 
covered  with  trap  blocks.  It  branches,  or  is  intersected 
by  a  short  dyke  £  m.  N.  E.  of  Boyertown.  Two  miles  S. 
of  Kinzer's  it  cuts  the  hornblende  gangue  rock  of  the 
Gap  Nickel  mine  ;  and  a  small  parallel  dyke  here  runs  half 
a  mile  distant  from  it,  a  mile  above  Georgetown,  both 
changing  their  course  locally  to  S.  by  W.  Several  such 
local  fluctuations  from  a  perfectly  straight  course  are 
noticed  before  it  reaches  the  Susquehanna  at  the  mouth  of 
Peters  creek.  It  may  extend  into  Maryland  but  is  not 

by  ignition,  6;  silica,  39;  alumina,  32;  ferrous  oxide,  9;  ferric  oxide,  2.2; 
potassa,  5.3  ;  magnesa,  3. 1 ;  soda,  2 ;  titanic  acid,  1.2 ;  phos.  acid,  0.5  ;  niccolous 
oxide  (with  a  trace  of  cobalotus  oxide),  0.06. 


454  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

traceable  on  the  surface  for  six  miles  S.  W.  of  Peach  Bot- 
tom ;  then  a  dyke  is  to  be  seen  half  a  mile  south  of  the 
State  line,  and  a  mile  south  of  the  roofing  slate  quarry 
ridge.* 

That  the  roofing  slates  have  been  produced  by  plutonic 
action  I  cannot  think,  for  those  in  the  Lehigh  country  are 
far  removed  from  any  such  influence.  It  is  possible  that 
there  may  be  a  closer  connection  between  the  dyke  and  the 
nickel  ore.  The  fountain  seat  of  such  a  dyke  must  evi- 
dently be  at  a  great  depth. 

In  York  county  two  trap  dykes  cut  the  limestone  rocks, 
one  four  miles  east  of  York,  the  other  two  miles  west  of 
York. — The  Loganmlle  dyke,  about  13  miles  long,  runs  in 
a  N.  N.  E.  direction,  with  a  deflection  and  a  short  branch 
at  Logansville,  and  a  true  north  course  from  Longstown  to 
the  Wrightsville  railroad,  where  it  seems  to  terminate  at 
the  synclinal  axis  of  the  York  valley  limestone  belt. — The 
Staresmlle  dyke,  six  miles  long,  runs  N.  by  E.  from  the 
south  edge  of  the  York  valley  limestone  belt,  across  the 
Shortline  RR.  2£  m.  S.  W.  of  York  to  the  edge  of  the  Trias 
at  Staresville.  If  continued  under  the  Trias  6  miles  further 
northward  it  would  join  the  great  trap  outburst  on  the 
Susquehanna  between  New  Holland  and  Groldsborough.  It 
cuts  the  Codorus  limestone  beds  its  whole  visible  length, 
and  throws  a  short  branch  S.  W.  also  in  limestone. f  In 
this  case  as  in  that  of  the  Conshohocken  dyke  no  production 
of  white  marble  appears  as  due  to  igneous  action. 

In  Cumberland  county  we  have  the  most  remarkable  ex- 
hibition of  trap  outside  the  Trias  region.  It  is  like  the 
Sinking  Spring  dyke  in  Berks  county,  but  vastly  larger  and 

*See  Prof.  Frazer's  detailed  description  of  this  dyke  in  his  report  on  Lan- 
caster county,  C3.  p.  28  to  31 ;  also  the  colored  county  map  in  C3 ;  also 
Hand  Atlas,  map  No.  35. — On  page  78  it  is  said  that  the  dyke  was  traceable 
only  by  its  boulders  across  Eden  township.  See  other  similar  references 
elsewhere  in  C3. 

f  See  the  colored  geological  map  of  York  county  in  Report  C2.  The  rep- 
resentation in  the  Hand  Atlas  X,  map  No,  61,  is  not  quite  correct  There  is 
a  short  dyke  represented  cutting  the  limestone  area  at  the  N.  W.  line  of  York 
Bounty  coming  in  from  Cumberland  county. 


TRAP   DYKES   IN   NO.    II.  455 

infinitely  more  instructive  as  to  the  source  of  the  lava ;  lo- 
cating it  in  fact  several  miles  beneath  the  present  surface  ; 
for  it  is  incredible  that  lava,  however  fluid,  could  flow 
through  a  narrow  crack  horizontally  a  distance  of  25  miles  ; 
and  even  if  this  could  be  done  for  the  single  dyke  which 
crosses  the  Great  Valley  and  the  Perry  County  Cove,  it 
would  not  generate  the  three  other  short  parallel  associated 
dykes  in  Perry  county  which  do  not  appear  at  all  in  the 
Great  Valley.  Moreover  the  thickest  part  of  the  dyke  is 
in  the  Cove.  Evidently  the  focus  of  activity  must  be  located 
under  Perry  county,  and  be  in  some  way  connected  with 
the  faulted,  overturned,  profoundly  deep  Cove  synclinal. 

As  the  dyke  cuts  the  slate  and  limestone  belts  of  Cum- 
berland county,  and  is  probably  continuous  (underground) 
through  the  South  mountains  into  Adams  county,  (there 
connected  with  the  great  outbursts  of  trap  in  the  Trias,)  we 
must  take  it  for  granted  that  in  Perry  county  it  descends 
through  all  the  formations  from  XI  to  II,  into  the  Cam- 
brians, and  through  them  into  the  floor  of  gneiss.  There 
are  19,000'  of  strata  exhibited  in  Perry,  and  at  least  6000' 
more  in  Cumberland,  making  25,000'  to  the  bottom  beds  of 
II ;  to  which  must  be  added  say  15,000'  of  South  Mountain 
Cambrian  rocks.  It  is  evident  then  that  in  Perry  county 
the  lava  has  ascended  from  a  depth  of  from  5  to  7  miles  to 
reach  the  present  surface.  How  far  it  rose  above  the  pres- 
ent surface  of  the  Great  Valley  would  depend  upon  the  pre- 
cise Post-triassic  age  of  the  dyke  ;  for,  if  it  reached  and  over- 
flowed a  surface  already  sculptured  by  erosion  during  the 
whole  Triassic  age,  all  that  upper  part  of  the  dyke  has 
been  swept  away,  and  nothing  remains  but  its  stem,  from 
the  present  surface  to  its  roots  in  the  deep. 

The  dyke  is  first  distinctly  seen  at  Boiling  Springs  on 
Yellow  Breeches  creek.  South  of  this  its  upper  edge  is 
probably  concealed  beneath  the  deep  alluvium  at  the  foot 
of  the  South  mountains,  across  which  it  might  probably  be 
traced,  for  Mr.  Lehman  in  his  topographical  survey  found 
fragments  of  trap  in  the  woods  on  the  line  of  the  dyke  pro- 
jected southward.* 

*On  the  colored  map  of  Cumberland  county  in  Atlas  D5,  a  branch  dyke 
is  seen  taking  off' from  near  Boiling  Springs  and  running  some  distances.  W  . 


456  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

From  Boiling  Springs  it  runs  in  a  slightly  waving  nearly 
straight  line  N.  10°  E.  10  miles  to  the  top  of  the  North  mount- 
ain 2  m.  E.  of  Sterritt's  gap.  Across  the  limestone  belt  of 
cleared  land  (here  7  miles  wide)  it  makes  a  continuous  ridge 
about  50'  high,  conspicuous  to  travelers  because  left  wooded 
by  the  farmers'  of  the  valley  ;  and  this  leafy  barrier  has 
been  adopted  as  a  township  line  between  S.  Middleton  and 
Monroe,  and  between  Middlesex  and  Silver  Spring  town- 
ships. It  crosses  the  turnpike  4  miles  E.  of  Carlisle,  and 
the  railroad  halfway  between  Middlesex  and  Kingston 
stations.  The  slate  belt  is  here  3  miles  wide  and  the  dyke 
upon  the  township  line  is  perfectly  straight ;  all  its  devia- 
tions from  a  straight  line  take  place  in  the  limestone  belt, 
and  these  deviations  are  undoubtedly  due  to  the  crumpled 
condition  of  the  limestone  formation,  although  the  frac- 
ture was  almost  transverse  to  the  general  strike. 

Descending  the  north  slope  of  the  North  mountain  into 
Perry  county  it  crosses  Fishing  Creek  valley  and  makes  the 
divide  which  casts  the  water  off  east  down  Fishing  Creek, 
and  west  into  Sherman  creek  upper  branches.  Keeping  on 
across  Cove  mountain  and  the  head  of  Cove  creek  it  as- 
cends the  slope  of  Peter' s  mountain  and  is  lost  near  the  sum- 
mit.* * 

As  the  Cumberland  county  dyke  cannot  be  properly  un- 
derstood if  only  studied  in  its  course  across  the  limestone 
and  slate  belts  of  the  Great  Valley,  I  will  give  here  Prof. 
Clay  pole's  description  of  it  in  Perry  county,  and  of  three 

*Dr.  Henderson's  description  of  it  published  by  Prof.  Rogers  in  Geol. 
Pa.  1858,  p.  366,  is  very  erroneous,  for  he  carries  it  across  the  Juniata  and 
Susquehanna  rivers  into  Dauphin  county.  It  is  but  justice  to  Dr.  Hender- 
son, who  was  one  of  the  best  geologists  of  his  day,  and  to  whom  we  owe  our 
first  accurate  knowledge  of  the  complicated  structure  of  Perry,  Juniata  and 
Mifflin  counties,  to  say  that  he  could  only  with  great  difficulty  at  that  early 
day  trace  the  line  of  the  dyke  upon  his  map  ;  and  the  line  which  he  laid 
down  on  his  map  was  transferred  to  the  Geological  Map  of  Pennsylvania, 
made  by  me  in  1842,  and  published  by  Professor  Rogers  in  the  Atlas  to  his 
Final  Report,  1858.  I  am  sorry  to  add  that  1  embodied  these  errors  in  the 
small  map  of  Perry  county,  Map  No.  45  of  the  Hand  Atlas,  Report  X,  drawn 
by  me  in  1878,  previous  to  Professor  Claypole's  elaborate  survey  of  the 
dykes,  published  in  Report  F2,  1885.  The  reader  is  therefore  referred  to  the 
second  (revised  and  amended)  colored  geological  map  of  Perry  county  in 
that  Report. 


TRAP   DYKES    IN    NO.    II. 


457 


Tl.    XXVI 


Jfap  dyke*  m  GiMnlerlanJ  and  Sherry  cotmtieb 


458  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

other  dykes  in  that  county  which  probably  have  an  under- 
connection  with  it  at  some  unknown  great  depth  beneath 
the  present  surface. 

Plate  xxvi,  p.  457,  shows  the  geographical  relationship 
of  these  four  Perry  county  dykes,  named  by  Prof.  Clay- 
pole  :  Great  Horseshoe,  Little  Horseshoe,  West  Duncannon 
and  East  Duncannon  dykes.* 

(-?.)  The  Great  Horseshoe  dyke,  Ironstone  ridge,  or  Cumber- 
berland  Valley  dyke. 

The  line  of  this  dyke  maybe  detected  by  loose  fragments 
on  the  south  side  of  Peters'  mountain  about  two  and  a  half 
miles  west  of  the  river  and  between  the  highest  terrace  and 
the  summit  of  the  mountain.  Its  course  is  plainly  indi- 
cated down  the  slope  by  the  same  evidence  from  terrace  to 
terrace,  with  a  bearing  of  S.  10°  W.  into  the  Cove  at  the 
foot  of  the  Horseshoe  and  almost  to  the  creek. 

Along  this  part  of  its  course  it  appears  to  be  the  widest 
of  all  the  dykes  in  the  Cove,  but  just  before  it  reaches  the 
creek  it  suddenly  and  markedly  increases  and  assumes 
comparatively  gigantic  proportions,  admirably  displaying 
both  the  trap  and  the  accompanying  rocks  altered  by  con- 
tact with  it.  The  sandy  beds  of  the  Mauch  Chunk  Red 
shales  (XI)  which  are  here  cut  through  are  changed  to  a 
dark  brown  and  chocolate  colored  material ;  the  red  shales 
themselves  are  in  some  places  burnt  into  a  mass  resembling 
half  made  brick,  but  not  usually  much  hardened.  Some 
fine  shale  beds,  however,  have  been  so  much  changed  that 
they  are  almost  as  tough  and  hard  as  the  trap  itself.  This 
change  in  the  appearance  of  the  rocks  at  this  point  has  led 

*  The  descriptions  are  in  his  own  words,  copied  from  his  report  F2,  pp. 
296-301.  On  the  map  I  have  renamed  his  West  Duncannon  the  Mid  Cove 
dyke,  which  extends  northward  into  Wheatfield  township  ;  and  I  have  ven- 
tured to  give  the  name  Duncannon  dyke  to  the  dyke  in  Watts  township,  as 
it  is  in  line  with  the  (East)  Duncannon  dyke  in  Penn  township;  and  this 
doubtless  deceived  Henderson  into  believing  that  the  Cumberland  county 
dyke  was  single  and  30  miles  long.  His  belief,  however,  may  after  all  be  a 
correct  one  ;  for  the  most  striking  fact  exhibited  on  the  map  is  the  N.  10°  E. 
direction  of  the  Cumberland  dyke,  the  Mid-cove  dyke,  and  the  Watts  town- 
ship dyke,  all  three  on  the  same  line,  while  sending  off  branches  to  the 
north,  as  if  there  was  but  one  dyke  in  the  deep. 


TRAP    DYKES    IN    NO.    II.  459 

to  considerable  excavation  in  the  belief  that  the  dark,  soft, 
sandy  shale  beds  contained  copper — a  belief  for  which  there 
is  of  course  not  the  slightest  foundation. 

The  excavation  serves  to  make  very  plain  the  striking 
development  of  the  dyke  at  this  point.  From  being  a  dyke 
very  much  resembling  the  other  three — perhaps  rather 
larger — it  suddenly  enlarges  and  becomes  nearly  WO  feet 
from  side  to  side.  The  bed  of  the  Cove  creek  and  the  flat 
marshy  ground  alongside  of  it,  overgrown  with  a  thicket  of 
laurel  in  some  places  impenetrable,  is  thickly  bestrewn 
with  massive  blocks  of  the  dyke  up  to  half  a  ton  in  weight. 
How  far  this  display  continues  through  the  wood  I  cannot 
say  nor  to  what  height  it  rises  on  the  north  flank  of  Cove 
mountain.  The  bearing  of  this  dyke  is  S.  10°  W. 

The  Great  Horseshoe  dyke  passes  through  Rye  town- 
ship almost  from  north  to  south  where  it  is  well  known  as 
the  Ironstone  ridge,  and  forms  a  watershed  across  the  valley. 
Coming  down  from  nearly  the  top  of  the  Cove  mountain  its 
track  may  be  followed  by  the  characteristic  belt  of  yellow 
soil  and  heavy  rounded  rusty  bowlders  through  the  woods, 
almost  along  the  road  (hence  called  the  Ridge  road),  to  the 
middle  of  the  valley.  The  land  on  both  sides  of  it  is  so 
encumbered  with  wreckage  from  the  dyke  that  it  is  left 
unfilled  and  uncleared.  But  it  is  at  the  crossing  of  the 
main  valley  road  that  the  most  magnificent  display  of  the 
Great  Horseshoe  dyke  occurs  in  Perry  county.  Here  the 
road  for  500  feet  on  each  side  of  the  line  is  embanked  with 
bowlders  that  have  been  removed  from  the  land  and  piled 
up  in  grand  disorder.  The  dyke  itself  does  not  probably 
exceed  200  feet  in  breadth,  but  its  fragments  strewn  along 
both  sides  make  it  seem  very  much  wider.  North  and 
south  of  this  point  the  exhibition  is  less  striking  but  the 
ridge  may  be  traced  without  difficulty  for  nearly  another 
mile,  when  it  is  lost  on  the  slope  of  the  Blue  mountains. 
The  nature  of  the  trap  and  further  details  may  be  found  in 
the  account  of  Penn  township. 

Traces  of  another  (the  Little  Horseshoe  dyke)  may  be 
found  about  500  yards  to  the  eastward  in  a  number  of  loose 
blocks  of  trap  scattered  along  the  road,  but  no  ridge  in  any 
degree  resembling  the  Great  Ironstone  ridge  can  be  seen. 


460  GEOLOGICAL   SURVEY    OF   PENNSYLVANIA. 

(0.)  The  Little  Horseshoe  dyke. 

About  a  quarter  of  a  mile  east  of  the  Great  Horseshoe 
dyke,  another  parallel  line  of  fragments  can  be  found  high 
up  the  south  slope  of  Peters'  mountain,  in  fact  upon  the 
highest  terrace.  Its  first  appearance,  so  far  as  I  am  aware, 
is  at  an  old  shaft  sunk  some  years  ago  under  the  impression 
that  the  trap  dyke  carried  an  ore  vein.  The  shaft  was  sunk 
to  a  depth  of  about  25  feet,  and  at  the  depth  of  about  22 
feet  many  blocks  of  the  hard  tough  dolerite  (trap  rock) 
were  thrown  out.  This  is  the  most  northerly  indication  of 
this  dyke  that  I  have  seen  in  the  cove.  Hence,  it  may  be 
followed  at  intervals  southward  down  the  slope  of  Peters' 
mountain,  forming  an  almost  continuous  line  through  the 
thickets  to  the  cleared  land  in  the  cove  below,  where  it 
crosses  first  a  field  and  then  the  road  leading  west  into  the 
woods  of  the  Horseshoe,  and  is  lost  to  view  at  the  creek, 
where  a  large  meadow  is  almost  ruined  by  the  number  of 
blocks  which  lie  scattered  about  upon  it.  Beyond  the  creek 
no  one,  so  far  as  I  can  learn,  has  succeeded  in  tracing  it,  so 
that  it  probably  does  not  rise  so  high  on  the  Cove  mountain 
as  it  does  on  Peters'  mountain. 

I  have  no  means  of  estimating  the  breadth  of  the  dyke 
but  judge  it  not  to  exceed  6  or  8  feet.  Its  bearing  is,  as 
nearly  as  I  could  ascertain  it,  south  10°  west. 

Its  southward  prolongation  into  Rye  township  is  only 
attested  by  a  number  of  loose  blocks  scattered  along  the 
road  about  500  yards  east  of  the  Great  Horseshoe  (Cumber- 
land Valley)  dyke  ;  but  no  ridge  is  made  by  it  in  the  topog- 
raphy of  the  surface. 

The  Mid  Cove  or  W.  Duncarinon  dyke. 

Half  way  between  the  head  of  the  cove  and  the  river,  and 
near  the  foot  of  Peters'  mountain,  a  range  of  trap  can  be 
readily  traced  It  crosses  Cove  creek  close  by  an  old  saw- 
mill pond,  now  dry,  and  then  shows  in  a  byway  on  the 
north  side  of  the  main  turnpike  road.  Following  it  over  a 
field  it  is  seen  very  plainly  in  the  bank,  and  then  runs  along 
keeping  parallel  with  the  same  road  as  far  as  the  foot  of  the 


TRAP    DYKES    IN    NO.    II.  461 

Cove  mountain.  In  front  of  the  farm-house  which  stands 
at  this  point  is  a  well  sunk  exactly  on  the  line  of  the  dyke. 
Mr.  J.  M.  White  who  sank  this  well  informed  me  that  he 
passed  through  the  dyke,  and  that  it  is  not  vertica  ,  but 
pitches  to  the  west  at  an  angle  of  about  45°.  The  greater 
part  of  the  well  was  sunk  in  the  red  shale,  the  dyke  being 
left  at  a  depth  of  about  8  feet.  It  measures  here  only 
about  6  or  8  feet,  and  consists  of  a  number  of  loose  blocks 
embedded  in  the  red  clay — the  product  of  their  own  decom- 
position. In  the  neighboring  field  a  pit  was  dug  to  examine 
the  dyke,  which  gave  the  same  results.  Crossing  the  road 
at  this  point  the  dyke  can  be  traced  about  100  yards  further 
through  the  orchard  into  the  wood,  where  all  traces  of  it 
are  lost,  nor  has  any  one,  to  my  knowledge,  ever  seen  it 
higher  on  the  hill. 

It  has  not  been  seen  in  Fishing  creek,  in  Rye  township  ; 
nor  in  Cumberland  county. 

But  it  extends  northwards  from  Peters'  mountain  into 
Wheatfield  township,  crossing  Sherman's  creek  and  the 
Little  Juniata  a  quarter  of  a  mile  only  from  the  river  at 
Duncannon.  A  mile  N.  of  Duncannon  it  bends  and  takes 
a  nearly  due  N.  course  to  the  turnpike  a  mile  S.  of  Losh's 
Run  station  on  the  P.  RR.,  beyond  which  it  is  not  seen.* 

(4)  The  (East)  Duncannon  dyke. 

About  three  quarters  of  a  mile  further  east  a  trap  dyke 
may  be  seen  in  the  roadside  about  \  mile  south  of  the  mouth 

*I  give  Prof.  Claypole's  detailed  account  of  this  part  of  it,  beginning  at 
the  north  and  going  south  : — Its  first  appearance  is  on  the  turnpike  road 
about  one  mile  S.  of  Losh's  Run  station,  P.  RR.  Its  next  appearance,  so 
far  as  I  am  aware,  is  on  the  road  leading  west  from  the  Aqueduct.  There  is 
no  trouble  in  following  it  from  this  point  by  an  almost  uninterrupted  series 
of  exposures  to  Duncannon.  Its  course  is  marked  by  the  red  color  of  the 
soil,  for  a  mile  due  south,  across  fields,  to  the  road  running  west  from  the 
railway  station  at  Juniata  bridge.  Here  a  pit  was  sunk  some  years  ago  in 
quest  of  ore  on  the  western  edge,  of  the  dyke,  to  a  depth  of  about  25  feet.  A 
drift  was  then  run  for  6  feet  into  it  in  the  attempt  to  penetrate  it.  This  made, 
•its  thickness  upwards  of  twelve  feet.  The  same  discolored  sandy  shales 
were  thrown  out  here  as  in  the  Cove. 

At  this  point  the  direction  of  the  dyke  suddenly  changes  ;  but  a  thin  vein 
of  trap  appears  to  continue  nearly  on  its  former  course,  as  indicated  by  an 
occasional  trap  pebble  in  the  low  ground.  Such  pebbles  have  been  found  in 


462  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

of  Sherman's  creek.  Thence  it  has  been  traced  up  the  hill- 
side, where  its  outcrop  has  been  followed,  in  a  vain  search 
for  iron  ore,  to  the  top,  but  not  to  the  crest  of  Peters' 
mountain.  The  dyke  cuts  through  it  near  the  brow  over- 
looking the  river.  It  continues  on  the  same  course,  S.  20°  W. 
down  the  south  slope  of  Peters'  mountain  into  the  Cove,  and 
may  be  followed  by  the  color  of  the  soil  and  the  loose  blocks 
lying  about  across  the  fields  to  the  main  road  up  the  Cove, 
which  road  it  crosses  just  east  of  a  farm-house.  Running 
on  thence  with  the  same  bearing,  it  may  be  seen  alongside 
of  the  road  (which  here  turns  to  the  south-southwest)  for 
about  200  yards,  where  it  crosses  a  lane  running  off  at  the 
next  angle  in  the  road.  Here  its  presence  is  marked  by  the 
usual  red  clay  and  bowlders.  Beyond  this  point  southward 
I  have  not  traced  it. 

In  Watts  township  between  the  Juniata  and  Susquehanna 
rivers  may  be  found  a  dyke  which  is  probably  a  continua- 
tion of  this  Duncannon  dyke  as  it  is  in  almost  exactly  the 
same  line,  but  the  interval  (from  Duncannon  to  the  N.  W. 
point  of  Duncan's  island)  is  3%  miles,  no  great  distance  for 
an  underground  connection. 

It  appears  about  £  m.  N.  of  Dr.  Reutter's  house  at  the 
Junction,  and  is  traceable  by  loose  blocks  3  miles  N.  10° 
B.  nearly  to  the  foot  of  Half  Falls  mountain.*  It  precisely 

the  run  close  by  the  place  where  the  change  occurs,  near  the  grist  mill  west 
of  Duncannon,  and  again  at  a  short  distance  behind  the  nail  factory.  These 
are  sufficient  to  indicate  a  faint  continuation  of  the  dyke  in  its  former  direc- 
tion as  far  as  to  the  north  foot  of  Peters'  mountain.  An  examination  of  the 
map  will  show  that  it  is  on  the  line  of  dyke  No.  3  in  the  Cove  before  de- 
scribed. 

But  the  main  mass  of  the  dyke  suddenly  bears  away  at  S.  30°  E.  down  a 
slope,  across  a  field,  passing  under  a  house  (as  shown  when  the  cellar  was 
dug)  and  so  reaching  the  river.  It  has  not  been  seen  in  the  bed  of  the  river  ; 
but  on  the  opposite  or  eastern  river  bank,  opposite  the  mouth  of  Sherman's 
creek,  and  exactly  on  the  right  course,  what  is  probably  the  same  dyke  is 
displayed  in  a  cutting  of  the  North  Central  railway. 

This  exposure  gives  an  opportunity  of  measuring  the  thickness  of  the  dyke, 
which  is  about  50  feet.  It  does  not  appear  to  rise  to  the  surface  ;  and  the 
rocks  on  both  sides  are  altered  as  in  the  case  of  the  Great  Horseshoe  dyke  in 
the  cove. 

*"  Had  time  allowed  might  have  been  followed  further.  The  last  trace 
of  it  seen  was  near  the  house  of  Mr.  M.  Peters."  F2,  p.  385. 


TRAP   DYKES   IN   NO.    II.  463 

resembles  the  Cove  traps,  a  hard,  tough,  dark  green,  almost 
black  dolerite,  containing  a  small  proportion  of  magnetic 
oxide  of  iron,  rusting  yellow  outside,  f 

The  most  remarkable  thing  about  these  dykes  is  this : 
not  one  of  them  lias  ever  been  detected  at  the  top  of  either 
of  the  two  mountains ;  the  East  Duncannon  and  Great 
Horseshoe  dykes  alone  rising  above  the  highest  terrace,  so 
far  as  known.  The  West  Duncannon  dyke  does  not  ap- 
pear to  rise  into  the  mountain  at  all,  its  exposure  ceasing 
sharply  at  the  foot.  It  is  not,  however,  impossible  that 
further  examination  may  modify  this  assertion  which  is 
based  on  negative  evidence  only.  Not  one  of  these  dykes  is 
yet  known  to  appear  upon  the  very  summit  of  either  Peters' 
or  Cove  mountain.  The  Great  Horseshoe  dyke  ranges  high- 
est, running,  as  has  been  shown,  up  to  the  topmost  terrace 
of  Peters'  mountain  on  its  southern  flank.  This  failure  of 
the  dykes  to  appear  at  the  summit  proves  the  moiintains  to 
be  older  than  the  dykes.  Now  since  the  Triassic  red  sand- 
stone of  York  county  is  cut  by  numerous  similar  dykes 
with  which  these  Perry  county  dykes  seem  to  be  con- 
nected, they  must  be  not  only  later  than  the  coal  measures, 
but  of  later  age  than  the  Trias  ;  but  as  no  such  dykes  are 
known  in  the  Cretaceous  beds  of  the  Atlantic  seaboard, 
our  dykes  must  be  older  than  the  Cretaceous  age. 

f  The  trap  of  Perry  county  is  a  hard,  very  tough,  dark,  heavy  and  fine- 
grained dolerite  containing  grains  of  magnetic  iron  ore  disseminated  through 
the  mass,  readily  discoverable  by  crushing  a  small  piece  with  the  hammer 
and  applying  a  magnet,  when  the  magnetite  immediately  clings  to  it  The 
presence  of  this  material  is  partly  the  cause  of  the  decay  which  takes  place 
at  the  surface  of  the  trap.  Under  the  action  of  moisture  the  magnetite  be- 
comes rusty  and  passes  into  brown  hematite.  The  outer  layer  of  stone  is 
softened  and  changes  color  to  a  rusty  yellow.  This  outside  layer  scales  off 
and  the  process  is  repeated  upon  the  new  surface  thus  exposed.  In  this  way 
from  year  to  year  a  red  clay  soil  is  produced  by  the  disintegration  of  the 
other  materials  of  the  rock,  felspar  and  hornblende,  colored  by  the  iron 
oxide.  In  consequence  of  the  abundance  of  this  red  clay  along  the  course 
of  the  trap  it  is  usually  called  by  the  residents  of  the  neighborhood  "iron 
ore,"  or  "  magnetic  ore  rock. "  But  it  is  not  likely  that  any  merchantable  iron 
ore  will  be  found  along  the  lines  of  these  dykes.  It.  is  often  a  task  of  great 
labor  to  dig  out  and  carry  away  the  fragments  from  the  fields  and  pile  them 
up  at  the  roadsides  where  their  subangular  form  and  rusty  color  make  them 
conspicuous  objects  to  the  passer-by.  They  all  consist  of  the  same  tough 
hard  dolerite,  showing  some  but  very  little  variation  in  composition  and 
fineness  at  different  places. 


464  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

Effects  of  trap. 

The  alteration  of  the  magnesian  limestone  rocks  noar  the 
trap  dykes  of  Berks  county  is  ascribed  by  Dr.  Genth  to  the 
infiltration  of  siliceous  waters.* 

Deweylite  and  serpentine  are  formed  out  of  the  magne- 
sium carbonate. 

Another  portion  of  the  magnesia  separates  as  brucite. 

The  calcium  carbonate  crystallizes  in  small  acicular  crys- 
tals and  radiating  columnar  masses  of  aragonite;  and  also 
in  crystals  and  coarse  granular  masses  of  calcite. 

The  alteration  of  dolomite  at  Fritz's  island  has  produced, 
directly  or  indirectly,  not  only  serpentine  and  deweylite, 
but  also  grossular,  a  beautiful  yellow  and  orange  vesum- 
anite,  apophyllite,  chabasite,  gismondite  (?),  thomsonile, 
mesolite,  stilbite,  datolite,  etc. 

Serpentine  in  No.  11. 

The  limestone  No.  II  near  Reading  is  described  by  Dr. 
Genth  as  "granular,  largely  altered  (by  silicious  waters) 
into  serpentine"  \  and  coated  with  colorless,  pearly  'brucite.\ 
The  brucite  occurs  also  in  brownish  yellow  thin  seams. 

Deweylite,  white,  yellowish,  brownish,  amorphous,  also 
occurs  in  round  grains,  stalactites,  botryoidal,  plates,  slabs 
(occasionally  more  than  I")  and  irregular  coatings.§  The 
slabs  are  often  arranged  in  layers,  white  and  brown,  often 
intimately  mixed  with  aragonite,  which  sometimes  sepa- 
rates in  radiating  columns  or  masses  (50mm  long) ;  the 
layers  often  separate  easily,  and  the  separation  planes  are 
covered  with  small  brilliant  aragonite  crystals.  The  ara- 
gonite has  often  changed  to  deweylite. 

The  change  from  dolomite  limestone  to  serpentine  can  be 
observed  in  all  its  stages  from  pure  dolomite  to  pure  ser- 

*At  Fritz's  island  ;  and  at  Wheatfleld  &  Ruth's  mines,  2  miles  E.  of  Fritz- 
town,  and  2  m.  S.  of  Sinking  spring.  Proc.  Ainer.  Soc.  Phila.  Oct.  2,  1885. 
See  also  descriptions  by  E.  F.  Smith,  D.  B.  Brunner  and  I.  Schoenfeld. 

f  Amer.  Phil.  Soc.  Proc.,  Phila.,  Oct.  2,  1885. 

fE.  F.  Smith's  analysis  of  it  (in  Amer.  Chem.  Jour.,  V.  281)  is  silica 
82.52;  magnesium  oxide,  66.78;  ferric  oxide,  0.44. 

§  Analysis  by  H.  F.  Keller,  silicic  oxide,  39.32;  magnesium  oxide,  41.14; 
lerrous  oxide,  0.51 ;  water,  18.41. 


TRAP   DYKES   IN   NO.    II.  465 

pentine ;  which  is  generally  a  greenish  yellow,  greenish 
white,  or  yellow,  but  also  sometimes  brownish  and  grayish.* 

Aragonite  and  calcite  are  frequently  associated.  Magne- 
tite is  occasionally  disseminated  in  fine  grains  through  the 
mass. 

Olivine.  Dr.  Genth  alludes  to  Dr.  Wadsworth's  theory 
that  the  Fritztown  serpentine  is  an  altered  olivine,  and  to 
his  assertion  that  the  specimens  show  unaltered  olivine^ 
and  says  :  "I  cannot  imagine  how  olivine  could  be  present 
in  this  rock,  and  what  it  is  which  he  (Dr.  Wadsworth)  has 
taken  for  that  mineral.  As  the  trap  is  of  triassic  or  post 
triassic  age,  it  is  impossible  for  olivine  or  any  other  kind  of 
volcanic  ash,  to  get  admittance  into  the  Siluro-Cambrian 
dolomite  strata  around  Reading." 

*  Analysis  by  H.  F.  Keller.  Ruth's  mine  :  Sil.  ox.,  42. 14 ;  mag.  ox.,  41.61 ; 
ferrous  ox.,  2.06;  water,  14.20. — Wheatfield  mine:  sil.  ox.,  41.46;  mag.  ox., 
44.68;  F.  ox.,  0.99;  water,  14.07. 

f  Lithological  studies,  by  M.  E.  Wadsworth,  Cambridge,  1884,  p.  152. 


30 


466 


GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 


Jfo.  II a,  GatetfarouA;  1),  Cha%y;  c,  Jrenton  Uuw, 

JYfr.  Ilia,  ^UJicti ;  '!),  "Xuclfarri  river  slafo. 
3o  Musk-ale  Chapter  WWII. 


Section  fromSalilEtitjIcM'".  Uirough  tfw 
XrrttoitcZineMinc. 


Section  alony  l/ie  Anticlinal  Axis. 

measures  to  lite  south. 


Mit^of  Ckufer  Valley. 


WHITE   LIMESTONES    AND   MARBLES   OP  NO.  II.          467 


CHAPTER  XXXIX. 

Wli'de  Limestones  and  Marbles  of  J\o.  77,   in  CJtestery 
Montgomery,  York  and  Centre  counties. 

The  white  marble  door  and  window  caps  and  sills  and 
the  blue-streaked  marble  front  door  steps  of  Philadelphia 
were  obtained  from  numerous  quarries  wrought  along  the 
southern  edge  of  the  Chester  County  valley,  east  and  west 
of  the  Schuylkill  river,  until  about  fifty  years  ago,  when 
the  marble  quarries  of  Vermont  began  their  successful  com- 
petition for  the  market.  Stephen  Girard  built  the  beauti- 
ful Corinthian  fagade  of  his  banking  house  in  Third  street 
of  native  white  marble.  The  United  States  Bank  in  Chest- 
nut street,  *  with  its  severely  beautiful  Doric  porticos,  was 
built  of  the  same  material,  now  rendered  doubly  pleasing 
to  the  artist's  eye  by  reason  of  the  warm  mellow  yellowish 
tint  which  time  has  given  to  it,  and  which  the  Greeks  de- 
lighted in.  One  side  of  the  superb  Corinthian  peristyle 
and  cella  wall  of  the  Girard  College  was  also  built  of  it, 
the  other  side  and  the  front  and  rear  porticos  being  from 
the  Vermont  quarries,  f 

One  reason  for  the  gradual  substitution  of  Vermont  for 
Chester  Valley  white  marble  was  the  great  expense  of  quar- 
rying in  the  Chester  valley,  and  the  cheapness  of  freight 
by  water  from  Vermont,  as  well  as  the  singular  develop- 
ment of  better  methods  of  getting  out  the  stone  there  ;  but 
there  was  another  pregnant  reason.  The  Pennsylvania 
white  marble  beds  are  locally  half  or  wholly  spoiled  by 
pyrites,  which  runs  in  streaks  through  them  and  subject 

*  Now  the  U.  S.  Custom  House. 

t  Its  57'  high  columns,  built  up  of  drums  6'  long,  compare  favorably  with 
those  of  the  Madelaine  in  Paris,  built  up  of  drums  only  about  1'  long, 
although  the  College  columns  are  spaced  so  much  further  apart  as  to  make 
them  look  too  slender;  and  the  close-set  double  row  of  the  Madelaine  gives 
to  that  splendid  monument  something  of  the  Doric  majesty  of  the  Parthenon, 
which  it  resembles  also  in  its  great  length  of  side  colonnades. 


468  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

them  to  a  slow  decay.  The  front  columns  of  the  Custom 
House,  exposed  to  the  northeast  storms  in  cold  weather, 
became  gradually  dilapidated,  and  are  now  patched  with 
pieces  of  new  marble  let  into  the  decayed  places  ;  and  such 
periodical  restorations  will  always  be  necessary.* 

The  marble  quarries  of  the  Chester  valley,  both  east  and 
west  of  the  Schuylkill,  were  opened  along  the  vertical  beds 
next  to  the  South  Valley  Hill,  and  the  marble  quality  is 
evidently  due  to  the  same  cause  to  which  the  verticality  of 
the  beds  is  due,  namely,  a  great  pressure  from  the  south 
crushing  the  rocks  and  permitting  infiltration  and  recrys- 
tallization.  f 

*  What  the  streaks  of  pyrites  do  to  this  marble  under  the  action  of  the 
acids  in  the  air,  and  of  the  frost,  similar  streaks  of  feldspar  do  to  the  syenite 
obelisks  of  Egypt  under  the  sand  blast  of  the  Khamzin  or  desert  wind  of 
March  and  April. 

f  "  It  is  worthy  of  remark,  that  all  the  marble  of  the  limestone  basin  of 
Montgomery  county  is  confined  to  the  synclinal  trough  adjoining  the  anti- 
clinal axis  now  described,  upon  the  N.;  the.genuine  marble  not  extending 
more  than  half  a  mile  from  the  uplifted  belt  of  slate,  nor  eastward  in  its  line 
of  strike  beyond  the  neighborhood  ot  the  point  of  sinking  down  of  the  Primal 
slates,  or  past  the  meridian  where  the  anticlinal  rapidly  loses  its  force.  As 
the  marble  is  evidenly  only  a  highly  metamorphic  variety  of  the  ordinary 
magnesian  limestone,  crystallized  and  changed  in  tint  by  igneous  action 
from  within  the  earth,  it  is  quite  natural  that  it  should  run  thus  parallel 
with  and  adjacent  to  this  line  of  uplift,  produced  as  this  has  been  by  the  pro- 
truding forces  of  the  interior.  The  whole  of  this  belt  of  marble  is  in  fact  but 
the  vertically  upturned,  and  occasionally  inverted,  Northern  side  of  this 
anticlinal  wave,  the  side  along  which  the  maximum  amount  of  igneous  in- 
fluence is  invariably  manifested.  In  offering  this  explanation  of  the  origin 
of  the  marble  by  metamorphism,  it  is  proper  to  observe  that  we  must  not 
ascribe  the  whole  of  the  change  to  its  proximity  to  the  line  of  anticlinal  up- 
lift of  the  Conshohocken  axis.  There  is  a  tendency  in  the  whole  of  the  lime- 
stone 01  the  Southern  half  of  the  general  valley  to  a  much  greater  degree  of 
alteration  than  belongs  to  the  same  rocks  in  the  Northern  half.  Through- 
out this  entire  synclinal  belt  the  metamorphism  from  heat,  of  course,  has 
been  far  greater  along  its  Southern  than  upon  its  Northern  margin,  partly 
because  the  strata  of  the  former  side'are  nearer  the  principal  injections  of 
igneous  rocks  of  the  whole  region,  and  partly  in  consequence  of  the  perpen- 
dicular or  even  inverted  position  which  has  permitted  the  subterranean 
-volcanic  vapors  to  pervade  them  more  freely  and  exert  their  maximum  in- 
fluence."— H.  D.  Rogers  in  Geo.  Pa.,  1858,  Vol.  1,  p.  163. 

West  of  the  Schuylkill,  Prof.  Rogers  remarks  :—"  Throughout  the  north- 
ern half  of  the  basin,  especially  where  the  limestone  observes  its  usually 
very  regular  southward  dip  of  seldom  more  than  45°,  the  rock  is  in  the  con- 
dition of  a  sub-crystalline,  and  even  earthy  or  purely  sedimentary  mag- 
jiesian  limestone,  and  its  bedding  is  for  the  most  part  very  uniform  and 


WHITE   LIMESTONES   AND   MARBLES   OF   NO.    II.         469 

In  New  Jersey,  Sussex  county,  two  limestone  formations 
surround  the  Franklin  zinc  mine,  one  blue  and  the  other 

rather  thick.  Its  color  is  a  pale  grayish  blue,  except  in  neighborhoods  like 
that  on  the  Schuylkill  below  Norristown,  where  a  partial  metamorphism 
has  approached  the  northern  border,  and  it  is  then,  very  frequently,  a  pale 
straw-yellow  and  bluish-white.  The  interleaved  thin  layers  of  argillaceous 
matter  which  so  frequently  separate  the  beds  of  the  limestone  are  in  the 
condition  of  an  indurated  clay-slate,  but  seldom  show  even  incipient  crys- 
tallization. In  many  instances  wide  bands  of  the  limestone,  along  its 
northern  outcrop,  exhibit  numerous  cross-joints  intersecting  the  beds  in 
nearly  all  directions  and  causing  the  rock  in  certain  quarries  to  break  into 
a  mere  rubble  of  small  angular  fragments,  assisting  much  the  labors  of  the 
quarryman  and  Hmeburner ;  but  these  joints,  and  the  before-mentioned 
semi-crystalline  texture,  are  the  limits  to  which  the  metamorphism  of  the 
rock  has  reached,  a  true  parallel  slaty  cleavage  being  seldom  or  never  dis- 
cernible. 

"  But  the  state  in  which  the  very  same  beds  exist,  where  they  rise  per- 
pendicularly or  with  inversion  to  their  southern  outcrop  after  passing  the 
synclinal  turn  in  the  center  of  the  basin,  is  very  different  from  all  this,  and 
in  striking  contrast  The  faintly  crystalline  and  earthy  limestone  is  here  a 
distinctly  crystallized,  often  a  granular  marble.  Its  color  is  changed  to  a 
brilliant  white,  or  to  a  mottling  of  purely  white  and  dark  blue,  from  the 
presence  of  segregated  or  half-developed  graphite;  and  the  dispersed  fer- 
ruginous matter  is  here  in  a  state  of  minute  solitary  crystals  of  sulphurate 
of  iron  disseminated  through  the  body  of  stone.  The  rock,  instead  of  lying 
in  thick,  often  massive  beds,  is  cleft  into  thin  plates  by  innumerable  natural 
fissures  or  cleavage-planes,  not  parallel  with  the  stratification,  but  dipping 
steeply  southward  or  acutely  across  it,  and  these  fissures  are  filled  and 
lined  with  distinctly  crystalline  flaky  talcose  and  micaceous  matter,  some- 
times talc  and  mica  fully  developed.  The  partings  of  slate  between  the  lime- 
stone layers  have  been  converted  to  laminae  of  talc-slate,  in  which  there  is 
often  a  cleavage-structure  distinctly  discernible,  much  more  intimate  than 
that  in  the  altered  limestone,  but  dipping  in  parallelism  with  it  Viewed 
edgewise,  a  fresh  exposure  of  the  most  altered  limestone,  such  as  is  visible 
on  the  River  Schuylkill  near  Conshohocken,  has  the  aspect  of  a  blue  and 
mottled  marble,  streaked  with  films  of  talc,  and  shivered  by  innumerable 
cleavage-joints;  but  viewed  face-wise,  the  layers  and  fragments  have  the  as- 
pect ot  a  talcose  or  micaceous  slate,  so  copious  is  the  covering  of  talc  and 
mica  upon  their  surfaces."— H.  D.  Rogers,  Geol.  Pa.,  p.  213. 

"The  portion  of  the  formation  which  enters  Abington  township  is  more 
slaty  and  fractured  than  that  further  to  the  W.,  and  it  also  contains  a  larger 
amount  of  silicious  or  sandy  matter.  Those  portions  of  the  rock  which  are 
exposed,  or  are  nearest  to  the  surface,  have  in  many  places  undergone  partial 
decomposition,  and  have  the  appearance  of  a  white  calcareous  sand.  This 
sandy  aspect  of  the  limestones  may  be  observed  in  all  the  quarries  in  the 
neighborhood  of  Sandy  Run,  and  also  at  many  other  localities.  Unless  the  rock 
has  undergone  partial  decomposition,  the  limestone  is  crystalline  and  granu- 
lar. It  varies  in  color  from  blue  to  white,  as  a  greater  or  less  amount  of  carbon- 
aceous matter  chances  to  enter  into  its  composition.  Each  of  these  colors  is 
not  confined  to  a  particular  stratum,  but  changes  repeatedly  in  the  same 


470  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

white.  They  were  supposed  to  belong  to  one  formation, 
one  part  of  which  had  been  subjected  to  some  influence, 

beds;  and,  indeed,  the  area  occupied  by  one  particular  color  is  usually  very 
small.  The  dip  throughout  the  whole  formation  is  remarkably  uniform. 
Near  Sandy  Run  it  is  towards  the  S.  and  S.S.E.  Quarries  and  pits  have 
been  opened  on  almost  every  farm  along  Sandy  Run.  One  of  the  largest  in 
this  vicinity  is  on  the  farm  of  Mr.  Fitzwater,  near  Fitzwatertown.  The  lime- 
stone is  chiefly  blue,  the  dip  S.S.E.,  at  an  angle  of  about  60°. 

"  On  the  turnpike  opposite  Sellerstown,  a  limestone  quarry  of  some  size  is 
wrought,  the  rock  making  an  excellent  lime.  An  extensive  quarry  of  the 
same  nearly  white  variety  of  the  limestone  exists  on  Mather's  farm.  There 
the  beds  are  crossed  by  very  regular  joints,  giving  the  appearance  of  a  stra- 
tification in  another  direction;  the  true  dip  is  towards  the  S.  Near  the  Ger- 
mantown  turnpike,  about  a  fourth  of  a  mile  above  the  Plymouth  Meeting- 
house, are  good  limestone  quarries.  Much  of  the  stone  in  this  neighbor- 
hood is  beautifully  white,  though  some  layers  occur  having  a  more  or  less 
bluish  tint.  The  weathered  surface  of  many  bods  is  rough  and  sandy,  show- 
ing some  silicious  matter  in  the  rock. 

" Spring  Mill.—  North  of  the  Furnace  200  yards  there  is  a  large  quarry  in 
the  limestone  near  the  southern  edge  of  the  formation,  in  which  the  dip  is 
85°  to  S.  10°  E.  The  southern  side  of  the  quarry  is  massive  and  jointedi 
and  the  dip  planes  are  almost  effaced;  the  northern  side  is  more  thin-bedded 
and  talcose,  of  a  bluish  white  color,  and  its  structure  very  crystalline. 

"In  that  portion  of  the  Limestone  Valley  which  occupies  the  southern 
part  of  Upper  Merion  township,  especially  in  the  immediate  vicinity  of  the 
Schuylkill,  there  are  numerous  and  extensive  quarries,  furnishing  a  large 
supply  of  the  rock,  a  portion  of  which  is  transported  to  Philadelphia,  and 
other  places,  by  the  several  railroads  and  the  Schulkill  navigation;  but  a 
large  amount  is  converted  into  lime  on  the  spot,  designed  lor  the  same 
markets. 

"  A  large  quarry  of  limestone  is  wrought  on  the  west  side  of  the  Schuyl- 
kill, two  or  three  miles  below  Valley  Forge,  where  the  rock  is  tolerably 
thick-bedded,  and  of  a  light  color.  The  quarried  stone  is  conveyed  to  the 
river  by  a  railroad,  and  thence  taken  by  boats  to  the  various  limekilns. 
Extensive  quarries  have  also  been  opened  near  the  Valley  Church,  where 
the  limestone  is  very  similar  to  that  of  the  last  locality,  dipping  steeply 
south,  being  of  a  light  tint,  and  furnishing  an  excellent  lime.  On  the  road 
from  Glassley  to  Valley  Forge,  near  the  county  line,  there  is  a  small  bed  of 
slaty  talcose  calcareous  rock  extending  E.  and  W.  about  three  furlongs  in 
length  towards  Valley  Creek.  It  constitutes  a  small  hill,  over  the  east  end 
of  which  the  road  passes.  Near  Valley  Forge  occurs  a  stratum  of  felspathic 
rock  like  that  seen  at  Barren  Hill.  It  is  exposed  in  the  creek,  and  occasion- 
ally appears  overlying  the  Primal  white  sandstone  at  the  foot  of  the  North 
Valley  Hill,  a  little  East  of  the  North  Valley  Church.  The  limestone  near 
the  White  Horse  Tavern  in  East  Whiteland  township  is  occasionally  talcose 
and  slaty.  Near  the  Steamboat  Tavern  the  more  usual  granular  structure 
prevails:  throughout  all  this  range,  however,  the  rock  yields  an  excellent 
lime. 

"At  Downingtown  the  limestone  is  chiefly  of  a  light  color,  and  compact. 
Several  quarries  of  compact  and  granular  limestone  have  been  opened  in 


WHITE  LIMESTONES  AND   MARBLES   OF   NO.    II.         471 

heat  perhaps,  or  pressure,  which  had  whitened  it.  But  in 
1863  Prof.  Cook  showed  that  the  blue  limestone  beds,  dip- 

tbis  vicinity.  The  width  of  the  formation  near  the  East  Cain  Church  is  re- 
duced to  about  three-fourths  of  a  mile.  It  is  somewhat  variable,  being  de- 
pendent, probably,  upon  the  angle  of  the  dip,  which,  however,  is  pretty  con- 
stant. At  Coatesville  it  does  not  exceed  three  furlongs.  At  Bell's  Quarry, 
Midway,  the  rock  is  of  a  light  color.  About  one  mile  east  of  Trueman'g 
Mill,  we  find  a  small  bed  of  white  clay,  derived  from  the  decomposition  of 
an  altered  felspathic  slate,  lying  between  the  limestone  and  the  talc  slates. 
In  the  vicinit}'  of  Buck's  RunandParkesburg  the  limestone  becomes  darker 
and  more  slaty.  Passing  Cloud's  Mill  into  Lancaster  county,  it  gradually 
declines  in  thickness,  beingat  Cooper's  Fulling  Mill,  in  Strasburg  township, 
not  more  than  two  furlongs  wide.  At  its  termination  in  Bart  township  it 
becomes  more  than  usually  sandy,  especially  near  its  margin.  The  main 
belt  seems  to  terminate  on  Eckman's  Run  but  another  small  lenticular  belt 
shows  itself  a  mile  and  a  half  further  to  the  west,  on  the  promises  of  Mrs. 
Bare,  where  the  rock  is  quarried."— Geol.  Pa.,  1858,  Vol  I,  p.  214. 

In  Montgomery  county: — "The  quarrying  of  marble  in  this  district  was 
commenced  about  75  years  ago,  by  Daniel  Hitner.  For  the  last  15  or  16  years 
the  average  quantity  sent  from  the  quarries  of  Marble  Hall,  owned  and 
wrought  by  the  present  proprietor,  Daniel  O.  Hitner,  has  been  about  25,000 
cubic  feet 

The  belt  of  marble  is  nearly  three-fourths  of  a  mile.  wide.  Marble  Hall, 
on  the  Perkiomen  Turnpike,  is  the  easternmost  point  at  which  good  build- 
ing marble  is  wrought,  though  the  belt  is  known  to  continue  further.  It 
extends  thence  to  the  Schuylkill  nearly  to  the  Chester  county  line. 

The  largest  quarry  of  all  is  that  of  Marble  Hall ;  here  the  strata  dip  to  S.  20°, 
E.  about  85°,  presenting  in  one  or  two  places  a  flatter  inclination.  This 
quarry  is  not  less  than  some  400  feet  in  length,  and  at  the  top  is  60  or  70  feet 
wide.  The  greatest  depth  to  which  the  quarry  has  been  sunk  is  265  feet. 
At  this  depth  were  procured  the  blocks  of  beautiful  white  marble  sent  by 
direction  of  the  State  of  Pennsylvania,  and  by  the  city  of  Philadelphia,  to  the 
great  monumentat  Washington.  At  this  depth  the  stratum  of  white  marble* 
for  which  this  quarry  is  chiefly  wrought,  has  a  thickness  of  5  feet;  but  the 
usual  thickness  of  this  bed  of  pure  white  stone  is  8  feet,  that  of  the  pure  and 
clouded  white  together  being  generally  about  20  feet.  Mr.  Hitner  has  quarried 
blocks  6  feet  in  thickness,  though  the  general  thickness  of  the  blocks  readily 
procurable  does  not  exceed  2i  feet.  The  only  saccharoidal  or  statuary  marble 
in  this  or  any  of  the  quarries,  is  found  here  at  a  depth  of  120  feet,  in  a  layer 
of  only  6  inches  in  thickness.  It  is  of  a  yellowish  white  color  and  remark- 
able eveness  of  grain.  The  white  marble  is  used  for  monuments,  and  for 
the  finer  architectural  purposes.  It  now  sells  for  about  one  dollar  per  cubic 
foot. 

To  the  south  of  the  large  quarry  of  Marble  Hall,  which  besides  the  white 
marble,  yields  much  beautiful  clouded  or  shaded  stone,  there  is  a  quarry  of 
blue  and  black  marble,  distant  about  300  yards.  This  owned  by  Mr.  Lentz, 
but  now  wrought  by  Daniel  O.  Hitner.  This  blue  and  black  marble  now 
sells  for  about  40  cents  per  cubic  foot.  It  is  used  chiefly  for  4ronts  of  build- 
ings, for  monument  bases,  etc.  The  thickness  of  the  good  blue  marble  in 
this  quarry  is  22  leet,  and  that  of  the  black  variety  8  feet. 


472  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 


,  <Stcld  m«f  of  lit 

f/ntiii  reyiani  afCfiuta-  Co. 


fftotoyual  ittof,  of  Penjurfmjua,, 

(puaMedi'n  ISM) 
fa  iJtiutraU  tie  jtruc&tral  theory 


WHITE   LIMESTONES    AND   MARBLES   OF  NO.    II.         473 

ping  northwestward,  lie  upon  the  upturned  nearly  vertical 
southeast-dipping  white  limestone  beds.* 

In  York  county,  Pennsylvania,  Prof.  Frazer  was  tempted 
to  make  the  same  distinction  in  age  between  the  white  and 
blue  limestones  of  the  Codorus  valley. f 

Besides  these  quarries  in  the  vicinity  of  Marble  Hall,  there  are  others  about 
three-fourths  of  a  mile  north  from  Spring  Mill ;  one  set  owned  by  Robert 
T.  Potts,  another  adjoining  his  by  Mr.  Peter  Fritz.  The  marble  of  Potts' 
quarry  is  chiefly  of  the  clouded  variety,  besides  alittle  white  and  some  plain 
blue.  The  annual  yield  of  this  quarry  is  about  12,000cubic  feet.  The  quarry 
owned  by  Fritz  is  at  present  but  little  wrought.  Next  in  position  to  the  west- 
ward, but  still  seated  in  the  same  belt,  are  two  quarries  westward  of  the 
Schuylkill ;  these  are  Henderson's  and  Brook's,  in  Upper  Merion  township. 
Henderson's  the  nearest  to  the  Schuylkill,  affords  a  plain  blue  marble,  be- 
sides a  little  white.  Both  of  these  quarries  are  wrought  at  present  to  only 
a  moderate  extent. 

A  little  south  of  the  Valley  turnpike,  about  three  and  a  half  miles  E.  of 
Downingtown,  is  the  extensive  quarry  of  superior  white  marble  which  has 
for  many  years  supplied  Philadelphia  with  the  beautiful  article  employed 
in  so  many  of  its  public  and  private  edifices.  It  is  on  the  farm  of  Mr.  John 
R.  Thomas.  The  beds  on  this  quarry  are  slightly  contorted.  The  portion 
worked  for  the  marble  separates  into  two  bauds.  The  rock  occurs  in  massive 
beds,  chiefly  white,  with  sometimes  a  bluish  tinge,  and  is  quarried  with 
great  facility.  It  has  been  much  used  in  the  construction  of  the  Girard  Col- 
lege and  other  public  buildings  which  adorn  Philadelphia  and  the  neighbor- 
ing towns.  This  marble  is  converted  into  a  good  lime,  but  its  crystalline  or 
granular  structure  causes  it  to  crumble  in  the  kiln,  making  it  a  little  difficult 
to  manage.  The  lime  from  this  variety  is  much  esteemed  by  masons,  being 
sold  in  Philadelphia  under  the  name  of  Fish-egg  lime. 

The  blue-mottled  limestone  or  marble  of  Whitemarsh,  occurring  at  the 
quarries  not  more  than  three-fourths  of  a  mile  north  of  the  northern  limit 
of  the  Primal  Strata,  is  evidently  on  the  south  side  of  the  trough,  or  folded 
synclinal  axis  of  the 'district.  This  is  further  proved  by  its  great  steepness  of 
dip,  about  80°.  Tt  is,  moreover,  of  the  maximum  degree  of  metamorphism 
or  crystallization  ;  contains  talcose  or  micaceous  laminae,  and  crystals  of  sul- 
phuret  of  iron,  etc. 

Strontia. — Near  Mr.  Hitner's  House,  Marble  Hall,  there  occurs  a  thin  bed 
of  very  ponderous  rock,  resembling  closely  a  white  crystalline  marble.  It 
contains  however,  but  a  moderate  proportion  of  carbonate  of  lime,  and  con- 
sists chiefly  of  the  carbonate  of  strontia."  Geol.  Pa.  1858,  vol.  1,  p.  215. 

*  Annual  Report  of  1863,  p.  7.— In  the  course  of  my  private  survey  of  the 
Franklin  mines  twenty  years  ago,  I  mapped  the  locality,  observed  this  non- 
conformability,  and  arrived  at  the  same  conclusion,  viz :  That  the  two 
formations  were  of  very  different  ages,  the  white  much  older  than  the  blue  ; 
the  zinc  deposits  being  in  the  white. 

t See  Report  CC,  page  132-3.  Dr.  Frazer  says: — "In  Detweiler's  quarry, 
which  is  a  little  more  than  half  a  mile  north  of  the  Columbia  bridge  [in  York 
county]  there  exists  a  conglomerate  consisting  of  a  blue  limestone  holding 
rounded  pebbles  of  white  limestone  within  it  The  limestone  exposed 


474  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

In  the  Chester  county  valley,  no  such  time  distinction 
has  ever  been  suggested  between  the  blue  limestone  beds 
of  the  north  side  and  middle  of  the  valley,  and  the  white 
marble  beds  of  the  south  side  of  the  valley;  although  the 
dip  of  the  former  is  moderately  southward,  while  that  of  the 
latter  is  nearly  vertical.  For,  on  both  theories  of  structure, 
the  synclinal  and  the  monoclinal,  no  such  distinction  was 
necessary.  In  fact,  on  the  synclinal  theory  the  blue  beds 
turn  up  as  white  beds;  while  on  the  monoclinal  theory  the 
blue  beds,  instead  of  overlying,  underlie  the  white  beds. 
But  if  it  could  be  proven  the  white  beds  at  Franklin  arid  at 
York  be  the  oldest,  then  we  must  suppose  a  fault  to  run 
through  the  Chester  valley  just  north  of  the  marble  quarries. 
This  is  possible,  but  not  demonstrable  ;  nor  is  it  a  probable 
supposition  since  it  ignores  the  Chiques  rock;  and  we  have 
no  place  in  the  Cambrian  into  which  to  put  the  marbles. 

Since  the  death  of  mv  lamented  friend,  the  State  Geologist 
of  New  Jersey,  an  important  report  of  recent  surveys  in 
the  white  and  blue  limestone  valleys  of  northern  New 
Jersey,  made  by  Mr.  Frank  L.  Nason,  Assistant  Geologist, 
has  been  published  in  the  N.  J.  Annual  Report  for  1890, 
under  the  title:  "  The  post  archcean  age  of  the  white  lime- 
stones of  Sussex  county.  N.  «/.,"  in  which  the  reader  will 
find  a  large  array  of  facts,  evidently  observed  with  great 
care,  skilfully  correlated,  and  ably  discussed,  and  the  con- 
clusion arrived  at  that  there  is  no  geological  time  distinc- 
tion between  the  white  and  blue  limestones;  that  they  are 
of  the  same  age,  belong  to  the  same  formation,  and  are  in 
fact  merely  the  same  beds  in  different  conditions;  that  they 
can  be  traced  along  their  outcrops  so  as  to  be  observed  to 
change  into  one  another,  the  white  into  the  blue,  and  the 
blue  into  the  white;  that  the  white  is  merely  the  blue  altered 
by  heat,  pressure  and  chemical  alteration  and  crystalliza- 
tion; that  the  change  is  alwaj^s  at  the  contact  of  some  plu- 
tonic  rock,  and  in  proportion  to  the  quantity  of  the  disturb. 

between  this  quarry  and  the  northern  edge  of  the  belt  [of  York  county 
limestone]  is  generally  white  and  of  a  more  earthy  character  than  the  aver- 
age York  limestone.  The  pebbles  were  of  course  fragments  of  an  older 
limestone  than  that  which  enclosed  them."  See  also  his  report  C,  Chapter 
XII,  p.  303  ;  and  his  analyses  of  six  different  limestones,  on  p.  307. 


WHITE   LIMESTONES   AND   MARBLE3   OF   NO.    II.         475 

ing  agent;  and  that  all  the  steps  of  the  change  of  the  blue 
into  white  are  easily  observable. 

The  distinctive  features  are:  (1)  that  the  White  is  crystal- 
line and  sparry,  a  true  marble;  the  Blue,  granular,  a  true 
limestone;  (2)  that  the  White  contains  an  abundance  of 
graphite  (plumbago)  crystals;  the  Blue,  little  or  no  graph- 
ite; (3)  the  White  has  no  fossils;  the  Blue  has  fossils. 

But  on  the  other  hand:  (1)  The  White  is  not  always 
highly  crystalline  and  sparry;  nor  is  the  Blue  everywhere 
non-crystalline  and  blue.  (2)  The  Blue  sometimes  carries 
graphite  and  fossils  as  well.  (3)  The  White  marbles  grad- 
uate into  a  fine-grained  clouded  blue  marble  (like  the  door- 
step marbles  once  so  commonly  used  in  Philadelphia) ; 
while  the  Blue  ranges  from  an  earthy  granular  to  a  white 
or  cream  colored  graphite  marble.  (4)  The  White,  slightly- 
changed  limestone  holds  flinty  nodules  nearly  or  quite 
changed  to  crystalline  quartz;  but  the  Blue  limestone  also 
has  characteristically  large  flint  nodules,  which  often,  al- 
though not  at  all  changed,  have  scales  of  graphite  enclosed 
in  them.  (5)  The  White  beds  have  boulder-like  masses  of 
fine-grained,  banded  limestone,  surrounded  by  coarsely 
crystalline  marble.  (6)  The  Blue  limestones  are  often 
crushed  into  breccia,  the  fragments  being  cemented  by  crys- 
talline limestone,  and  both  the  fragments  and  their  cement 
carry  graphite.  (7)  The  quantity  of  graphite  in  the  White 
marble  beds,  in  the  Blue  limestone  beds  and  in  fossiliferous 
sandstone  beds,  increases  as  the  distance  diminishes  from  the 
face  of  the  igneous  rocks  which  have  produced  these  changes. 
(8)  A  last  fact  of  the  utmost  importance;  sandstone  beds 
of  exactly  the  same  texture  and  mineral  composition  under- 
lie both  the  White  marble  and  the  Blue  limestone,  and  are 
changed  intoquartzite  beds,  holding  graphite,  when  in  con- 
tact with  the  igneous  rocks.  These  sandstones  are  some- 
times conglomerates,  holding  large,  irregularly  shaped, 
rounded  pebbles  of  quartz.  When  changed  the  sandstone 
shows  crystals  of  fresh  looking  feldspar  (orthoclase  ?)  and 
white  mica  scales,  and  is  then  hard  to  distinguish  from  the 
neighboring  igneous  granite.  Hematite  and  limonite  de- 


476 


GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 


cunt 


Thin-tedded  loncitoM.    ^    .  White  and jxle  tlut  ma£n<ti*n  hmetlone.        \         JynclinaL 


Yalley  limcilene  rritk  vertical  dip  and  clearage, 

Comhchoct-en 


Vdllny  limettcne  wit/tout  cleavage 
JoutA  i,fJtfo 


'fif-ZZ.Settim  nort&tfCoafarifa,  l^ciony  northeast. 


Jio:~23.36c&m  tiroatft-tht "JiiU-nirA  fffSfirfatajy. 


WHITE   LIMESTONES   AND   MARBLES   OF   NO.    II.         477 

posits  are  associated  with  both  the  sandstones  and  lime- 
stones. * 

In  the  Chester  county  valley  we  have  the  same  grouping 
of  white  marble  beds,  blue-banded  marble  beds,  blue  fos- 
siliferous  limestones,  sandstones  converted  into  quartzite, 
graphite  crystals  and  limonite  deposits.  We  have  the  same 
limited  range,  and  local  distribution  of  the  white  marbles. 
But  we  have  no  igneous  rocks  except  the  one  narrow  trap 
dyke  which  crosses  the  Schuylkill  at  Conshohocken ;  for 
the  nearest  granite  is  several  miles  away  to  the  south.  But 
the  trap  ranges  with  the  marble  beds  ;  and  these  are  wholly 
confined  to  the  vertically  upturned  south  side  of  the  valley. 
The  conversion  of  blue  limestone  beds  into  blue-banded 
marble  and  into  crystalline  marble  may  have  been  produced 
by  pressure. 

In  fact  I  had  pieces  of  white  marble  ground  thin  enough 
to  become  transparent,  and  then  under  a  microscope  of 
high  power  it  was  evident  that  the  rock  had  been  crushed 
to  minute  fragments  and  recemented  with  a  deposit  of  cal- 
cite,  which  gave  the  white  color  and  sparry  appearance ; 
and  it  could  be  seen  that  all  the  fragments  had  been  thrust 
more  or  less  round  their  centers,  for  they  were  minutely 
banded,  or  crossed  by  fine  lines,  which  obeyed  no  common 
direction  across  the  field  of  vision.  I  consider  this  a  phys- 
ical demonstration  that  the  white  marble  was  originally  a 
common  limestone,  and  that  its  formation  as  marble  had 
nothing  to  do  with  either  the  presence  or  absence  of  any 
trap  or  granite  or  other  heat  agency,  but  was  effected  by  a 
crushing  pressure  which  permitted  the  complete  infiltration 
of  lime  water,  and  the  recementation  of  its  fragments  with 
precipitated  calcite. 

*  Report  of  1890,  pp.  36,  37.  Prof.  Dana's  objections  to  Mr.  Nason's  views 
may  be  found  in  a  notice  of  the  N.  J.  report  published  in  the  July  No.  of  the 
Amer.  Jour.  Sci.,  1891.  To  these  objections  Mr.  Nason  replies  in  the  Sep- 
tember No.  of  the  American  Geologist,  1891,  pages  166  to  171,  by  a  clear  and 
succinct  restatement  of  his  field  observations,  laying  special  stress  on  the 
fact  that  the  change  of  blue  limestone  beds  into  white  marble  beds  may  be 
seen  between  two  points  only  50'  apart.  "  The  graphite  exists  in  every  stage 
from  the  bright  crystalline  stage  to  cloud  aggregations  of  carbonaceous 
matter  which  give  the  blue  color  to  the  blue  limestone." 


478  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

As  for  graphite,  its  occurrence  is  too  general  in  different 
kinds  of  rocks  to  base  a  very  valid  argument  upon  its  pres- 
ence in  any  one  kind  of  rock.  It  is  widely  disseminated 
in  slate  rocks  ;  and  the  dark  grey  color  of  the  Peach 
Bottom  roofing  slates  is  produced  by  so  small  a  quantity  as 
only  0.5  per  cent.  The  dark  limestone  beds  of  the  Lehigh 
valley  are  colored -by  impalpably  fine  graphite.  At  Pugh- 
town  in  Chester  county,  beds  charged  with  graphite  have 
been  ground  to  make  paint.  Sometimes  its  molecules  are 
aggregated  to  form  small  scattered  crystals  or  scales  ;  as  in 
crystalline  limestone  on  Monocacy  creek  4  m.  IN",  of  Bethle- 
hem ;  in  the  magnetic  iron  ore  at  Siessholtzville,  Lehigh 
county;  in  the  limonite  ore  at  Yellow  Springs,  Chester 
county  ;  in  bluish  and  other  quartz  in  various  parts  of  Ches- 
ter county.  Granular  and  foliated  masses  of  it  are  embedded 
in  the  talc  and  tremolite  beds  of  Chestnut  Hill,  N.  of  Easton. 
It  occurs  massive  at  Robinson's  Hill,  5m.  N.  of  Philadel- 
phia ;  and  at  Van  Arsdal's  quarry  near  Feisterville,  Bucks 
county.  A  mine  of  very  pure  plumbago  was  worked  a  cen- 
tury ago  near  Bustleton,  Bucks  county.* 

The  disseminated  microscopic  graphite  in  slate  rocks  may 
be  ascribed  to  an  original  charge  of  organic  matter  (animal 
or  vegetable,  or  both)  in  the  oceanic  mud.  The  same  ori- 
gin may  be  suggested  for  disseminated  microscopic  graphite 
in  the  limestone  formations.  But  when  it  comes  to  ex- 
plaining disseminate  crystal  plates  of  graphite  in  limestone 
changed  into  marble,  it  would  seem  to  be  necessary  not 
merely  to  call  in  the  aid  of  destructive  chemistry  to  set  free 
the  pure  carbon  from  the  organic  hydrocarbons,  by  driving 
off  the  hydrogen  to  other  alliances,  but  furthermore  to  call 
in  the  aid  of  those  forces  of  crystallization  which  have 
operated  in  and  upon  all  the  most  ancient  an£  so  called 
azoic  formations,  in  fact  upon  all  disturbed,  complicated 
and  crushed  formations,  chiefly  through  the  medium  of 
universally  and  perpetually  permeating  mineral  waters,  f 

*Vanuxem's  analysis  gave:  Carbon,  94.4;  silica,  2.6;  ox.  iron  and  mang., 
1.4  ;  water,  0.6 ;  loss,  1.0.  On  the  other  hand,  samples  from  S.  Coventry  and 
from  Berks  county  gave  to  Genth  :  Carbon,  only  7.20  and  10.85.  (Report  B, 
1875,  p.  8,  for  all  the  details  in  the  text  above,  and  in  this  foot  note.) 

t  The  geological  reader  of  these  remarks  may  be  reminded  of  the  flakes  of 


WHITE   MARBLE   IN   CENTRE   CO.  479 

The  white  magnesian  limestone  of  New  Jersey  seems  to 
have  been  the  only  one  quarried  for  lime  burning  before 
1864.*  One  analysis  gave  it  as  much  as  42.26  curb,  mag- 
nesia, only  1.40  alumina  and  oxide  of  iron  and  2.90  of  silica 
and  insoluble  matter ;  while  a  fossiliferous  limestone  had 
only  1.98  carb.  mag.,  4.70  alum.,  etc.,  and  5.80  sil.,  etc. 
Yet  it  is  well  known  that  piire  limestone  makes  a  white  and 
stronger  lime,  swells  more  in  slacking,  and  is  a  better  flux. 

The  white  crystalline  limestones  in  tlie  gneiss  of  the  N.  J. 
highlands,  along  their  whole  northwest  border,  are  very  like 
the  sedimentary  limestones  of  No.  II.  One  analysis  gave 
96.50:  1.13:  1.30:  0.30;  another,  53.00:  42.26:  3.50:  0.50. 
Consequently  one  was  a  pure  marble,  the  other  a  dolomite. f 

White  marble  in  Centre  Co. 

It  is  certainly  a  surprising  fact  that  white  crystalline 
limestone,  or  white  marble,  should  have  been  quarried  on 
Jac.  Bahrrer's  farm  near  Buffalo  run  in  Patton  township, 
Centre  county,  and  the  slabs  sold  in  Hollidaysburg  in  Blair 
county  for  gravestones  ;  the  strata  being  at  about  the 
middle  horizon  of  the  great  formation  No.  114  There  seems 
to  be  but  one  way  to  account  for  it,  viz :  by  the  infiltration 
of  limewater  to  such  an  extent  as  to  completely  charge  the 
rock  with  crystals  of  calcite.  §  But  such  infiltration  pre- 
supposes a  complete  crushing  up  of  the  rock,  as  in  the  case 
of  the  Chester  Valley  marbles,  which  we  find  in  all  stages 
of  change  from  pure  white  to  blue  and  white  ribbon  marble. 
But  the  Chester  Valley  marble  strata  have  been  pressed 
into  a  perfectly  vertical  attitude  between  a  vertical  slate 
formation  1000  feet  thick,  backed  by  gneiss  and  granite  on 

asphalt,  or  anthracite,  in  the  quartz  crystals  of  the  Mohawk  valley,  and 
other  places.  They  seem  to  have  been  deposited  in  internal  rifts  in  the 
crystal ;  but  they  are  completely  enclosed  in  the  body  of  the  silica,  and  per- 
haps floated  in  it  when  it  was  in  its  gelatinous  condition,  the  crystallization 
going  on  around  them. 

*  Cook,  An.  Rt.   1864,  p.  8. 

t  Cook,  An.  Rt.  1864,  p.  15. 

t  Prof.  Ewing's  special  report  in  Report  T4,  page  417. 

§  The  dark  blue  Trenton  limestone  beds  are  in  many  places  full  of  cracks 
filled  with  a  cement  of  white  calcite  ;  and  scattered  crystals  of  pure  or  nearly 
pure  calcite  are  quite  common  all  along  the  outcrops.  (T4,  417.) 


480  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 


M.l I  £&?nadone  in,  <M/rnfy(miery  and  (Sfwfor  Gat. 

.Gh,.  XXXIX. 


fy.19. 
Sen/an  Km  HillarCrat  toJha&Srmk  .VorrtondiAkinylan  TotmiAipt. 


Ky.20. 
the  tost  end  of  the  tinimtonf  raller .  Ak  union  Toimtfup. 


Tly.ll. 


Kff.M. 


Ill 


Hg. 
n-n  I 


ihnugk  anthoHorln-n  ISpriiy  Mill  atony  ,  Irh&kll  Krrr, 


Srtion  akny  the  SduylMI IB™-  itwyh  If.  CW/oWAv,  .  I'rprr 


WHITE   MARBLE   IN    CENTRE   CO.  481 

one  side  and  a  badly  crumpled  limestone  formation  perhaps 
3000  feet  thick,  on  the  other ;  with  every  kind  of  evidence 
of  oblique  strains  just  suited  to  the  disintegration  of  the 
mass,  exposing  it  to  easy  and  continuous  infiltration. 

In  the  Nittany  valley  the  great  anticlinal  is  indeed  in 
places  overthrown,  and  therefore  the  slip  and  slide  move- 
ment must  have  been  great ;  but  the  wave  form  is  normally 
regular,  and  oblique  crushing  not  a  necessary  consequence. 
Yet  it  may  have  occurred  at  particular  points,  perhaps 
many  such  ;  and  must  have  occurred  at  Bahrrer's  quarry. 
It  is,  however,  astonishing  that  the  infinitely  varied  and 
minute  complication,  distortion  and  warping  of  the  lime- 
stone strata  of  the  Great  Valley  should  not  have  produced 
the  same  effect  upon  them  as  in  the  Chester  Valley  ;  should 
not  have  created  white  marble  quarry-ground  at  least  equal 
to  that  of  New  Jersey  or  Vermont. 


Near  Ephrata,  in  northern  Lancaster  county,  a  quarry 
was  opened  many  years  ago  from  which  were  obtained  some 
good  pieces  of  marble  of  a  very  light  blue  tint  and  some  of 
it  decidedly  shaded.  Gteol.  Pa.  1858,  Vol.  1,  p.  222. 


81 


482  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 


CHAPTER  XL. 

Black  marble  in  No.  lie. 

The  "black  marble"  of  the  Musquito  or  Oval  valley  in 
Lycoming  county,  Armstrong  township,*  is  a  unique  rock 
in  Pennsylvania,  and  very  interesting  because  (1)  it  exactly 
resembles  a  Belgian  black  marble  (with  a  brownish  reflex- 
ion) used  for  the  body  of  French  mantel  clock  cases,  f  (2) 
it  marks  the  depth  to  which  this  oval  hole  in  the  Bald  Eagle 
mountain  has  been  excavated;  for  the  black  beds  are  un- 
doubtedly high  in  the  Trenton  limestone,  the  upper  division 
of  formation  114 

These  beds  are  crowded  with  brachiopod  shells,  and  con- 
tain many  specimens  of  Calymene  senaria,  Conrad,  one  of 
the  most  characteristic  and  widely  distributed  trilobites  of 
of  Trenton  age.§ 

A  similar  black  marble  is  quarried  at  Glen's  Falls  in 

*  Four  miles  southwest  of  Williamsport.  The  quarry  is  owned  by  the 
Penna.  Marble  Co.  (Col.  Potts  and  Mr.  A.  D.  Hepburn).  The  valley  is  5 
miles  long,  and  its  floor  about  500'  above  the  river  at  Williamsport  (or,  about 
1000'  A.  T.).  Quarry  abandoned  about  1875,  because  no  blocks  thicker  than 
10"  or  12"  could  be  got  out  from  the  36'  of  face  exposed.  Layers  dipping 
only  4°  N.  E.  representing  a  fall  of  the  crest  of  the  anticlinal  arch  in  that 
direction  (See  Report  G2,  76,  78).  Curiously  enough  the  rock  has  not  been 
found  in  Nippenose  valley. 

f  Much  of  the  rock  is  splintery.  Soft  rotten  layers  separate  hard  firm 
layers.  It  burns  to  a  fine  white  lime.  It  will  not  polish  well  by  ordinary 
processes,  but  can  be  polished  highly  by  extra  care.  It  breaks  up  when  ex- 
posed to  the  weather,  but  is  useful  for  indoor  furniture  (Letter  of  J.  G. 
Hammer,  March,  1886). 

JSee  however  the  so  called  black  marble  of  Hitner's  quarry  in  Mont- 
gomery county  mentioned  in  foot  note  to  p.  471  above,  last  paragraph. 

§  Vanuxem's  Senior  calymene  (N.  Y.  Rt.  1842,  p.  56),  a  name  which  has 
no  reference  to  the  6  tubercles  on  the  buckler  (Miller's  Am.  Pal.  Foss.,  p. 
213).  Conrad  named  it  in  1841.  Green  in  1832  gave  figures  of  three  casts 
which  he  called  C.  blumenbachii,  C.  callicephala,  C.  selenecephala,  which 
J.  Hall  considered  synonyms  of  C.  senaria  (Pal.  N.  Y.,  Vol.  I,  p.  238,  Plate 
64,  fig.  3a-n). 


BLACK   MARBLE   IN  NO.  He.  483 

northern  New  York.*  Dr.  Emmons  describes  it  as  there 
exposed  in  a  river  cliff  65'  high,  the  upper  rocks  being 
Trenton  limestone,  the  lower  calciferous  (Chazy)  limestone. 
Between  them  lies  the  black  marble  formation  10'  thick,  f 
So,  at  Isle  La  Motte  the  black  marble  (solid  12'  thick)  lies 
under  Trenton  limestone.  Where  it  occurs  at  Watertown 
on  the  Black  river  in  Jefferson  county  it  is  lumpy,  and  lies 
between  the  Trenton  and  Birdseye.  It  is  nowhere  seen  in 
the  Mohawk  valley,  where  the  Trenton  reposes  directly  on 
the  Birdseye  limestone  ;  and  this  makes  the  fact  of  its  ap- 
pearance in  the  Oval  valley  in  Pennsylvania,  and  nowhere 
else  in  the  state,  as  yet  noticed,  so  remarkable  and  interest- 
ing. It  makes  it  doubtful  also  whether  our  black  marble 
is  really  the  same  deposit  under  the  Trenton,  instead  of 
being  over  it.  In  fact  it  seems  almost  impossible  to  believe 
it  the  same :  for  the  Trenton  is  nearly  1000'  thick  on  the 
Bald  Eagle  anticlinal ;  and  the  Oval  valley  should  be  much 
larger  if  eroded  to  the  bottom  of  the  Trenton.:}: 

*  The  black  marble  at  Glen's  Falls  is  so  checked,  cracked  and  seamed 
with  flints  and  calc  spar  fossils,  that  very  few  beds  can  be  worked  with 
profit.  Its  color  is  jet  black,  its  grain  close  and  fine  and  slightly  crystalline. 
Being  rather  brittle  in  one  direction  it  requires  careful  handling  for  thin 
tables.  The  natural  division  planes  between  two  beds  often  are  studded 
with  projections  like  those  of  fibrous  sulphate  of  strontian,  fitting  into  each 
other,  and  sometimes  kept  apart  by  a  thin  film  of  slate,  showing  minute  fu- 
coidal  markings,  and  now  and  then  a  small  encrinite. 

fNat  Hist.  N.  Y.  1842,  pp.  110  and  180.  He  says  that  the  Trenton  beds 
here  are  60  or  70  in  number  varying  in  thickness  from  an  inch  to  several 
feet,  full  of  Trenton  fossils.  The  bottom  layers  are  gray  and  lying  on  the 
black  marble  are  quarried  with  it. 

i  Emmons  says  that  the  black  marble  fossils  are  not  exactly  those  of  the 
Trenton.  They  are  not  very  numerous  in  the  New  York  quarry  rock. 
Columnia  sulcata  is  quite  abundant,  sometimes  in  masses  of  half  a  bushel. 
Large  Orthocerata  are  common,  some  of  them  ten  feet  long  and  a  foot  in 
diameter  (as  in  Birdseye). — He  describes  cone-in-cone  as  a  fossil  (p.  111). — 
The  strontian-like  crystals  are  half  to  one  inch  long.  In  the  later  Niagara 
limestone  the  mineral  itself  has  been  preserved  ;  in  this  black  marble  only 
its  form  (p.  111).  Both  these  projections  and  the  cone-in-cone  show  that 
the  black  mud  remained  homogeneous  and  quiet  for  a  long  time  ;  no  doubt 
as  alocal  marsh,  but  either  subsequently  covered  with  deep  water  ;  or  along 
an  extensive  shore  to  which  storms  might  drive  the  gigantic  cephalopod 
shells  and  masses  of  coral  to  be  embedded  in  the  black  mud  when  dead, 
although  they  could  not  have  existed  even  in  its  vicinity  while  alive. 

Vanuxemin  his  Report  (N.  H.  N.  Y.  Third  Dist.  1842,  p.  43-45)  described 
some  light  grey  or  dark  grey  limestone  beds,  on  the  Birdseye  and  under  the 


484  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

Black  marble  in  No.  VI. 

There  is  a  so-called  black  marble  in  New  York  in  Forma- 
tion No.  VI.  It  is  the  lowest,  or  Tentaculite  limestone  sub- 
division of  the  Lower  Helderberg  group,  the  layers  of  which 
are  massive  and  dark  colored.* 

Trenton,  at  the  Mohawk  valley  quarries  (in  three  layers  2',  4'  and  7'  thick, 
at  Stanton's  quarry),  holding  accretions,  or  knobs,  and  (at  Putnam's 
quarry),  the  lower  layer  what  seem  to  be  4'  pebbles  of  yellowish  calciferous 
sandrock.  The  beds  are  as  good  limestone  as  the  Birdseye  beds  under  them 
but  otherwise  resemble  the  Trenton  beds  over  them.  They  hold  a  shell 
(Strophomena),  a  polyp,  a  coral  (Cyathophyllum},  etc.  Vanuxem  adds, 
that  these  bottom  beds  of  the  Trenton  form  the  surface  of  Nippenose  (Mus- 
quito)  valley  in  Penna.;  the  30'  "marble"  cliff  at  Frankford,  Ky.  (with  F. 
demissus  specks); and  the  Nashville  bluff  in  Tennessee,  where  the  layers  are 
brown  and  thin. 

Mather  in  his  report  of  the  First  Geological  district  of  N.  Y.  (1843,  pp.  399 
and  plate  24)  describes  the  black  marble  of  Glen's  Falls  near  Saratoga  more 
in  detail.  The  Hudson  cuts  through  70'  of  beds  :  Utica  black  slate  at  the 
top,  on  Trenton  limestone,  sawed  for  fire  places  ;  fifty  layers  ol  very  fossil- 
iferous  limestone  ;  2|'  grey  limestone  taking  a  fine  polish  ;  6"  darker  lime- 
stone used  for  door  steps  ;  10^'  black  marble  polishing  brilliantly,  with  lay- 
ers of  fossils  at  irregular  intervals,  2"  or  3"  thick,  and  extending  10'  or  %0' 
and  abruptly  stopping  (i.  e.  shell  banks).  Mather  (p.  403)  places  the  Isle 
la  Motte  black  marble  of  Emmons  in  the  Slack  River  Limestone  group, 
with  the  Birdseye  and  Chazy. 

*  Mather  alludes  to  it  in  his  Report  of  1843,  p.  327,  where  he  says  that  most 
of  the  Helderberg  rocks  south  of  the  Catskill  mountain  are  black,  dark  grey, 
and  veined  with  white,  but  massive,  and  susceptible  of  a  polish.  Vanuxem 
in  his  Report  of  1842,  p.  118,  calls  the  Pentamerus  beds  mottled  brown  and 
blackish  limestone  full  of  columnarice. 


THICKNESS    OF   NO.    II.  485 


CHAPTER  XLI. 
Thickness  of  No.  II  in  Lancaster  county  and  elsewhere. 

The  city  of  Lancaster  is  built  over  the  center  of  a  great 
limestone  plain  of  inexhaustible  fertility,  the  garden  of  the 
State.  It  reminds  the  traveler  of  Paris  seated  in  the 
center  of  the  fertile  and  populous  plain  of  Northern  France, 
through  which  meanders  the  river  Seine,  as  the  Conestoga 
meanders  through  Lancaster  county  from  northeast  to  south- 
west to  join  the  Susquehanna  at  Safe  Harbor.  But  here 
the  likeness  ends  ;  for  the  Cretaceous  strata  of  the  Paris 
basin  lie  almost  perfectly  horizontal  and  are  charged  with 
the  rainfall  which  has  collected  in  them  from  a  circle  of 
many  leagues,  and  which  is  easily  brought  to  the  surface 
by  artesian  wells. 

The  Lower  Silurian  limestone  strata  of  Lancaster  county, 
on  the  contrary,  descend  steeply  to  the  bottom  of  a  syn- 
clinal trough  at  least  a  half  mile  beneath  the  present  sur- 
face, the  center  line  of  which  runs  east  and  west,  crossing 
the  Conestoga  about  a  mile  below  the  city's  southern  limit; 
almost  all  the  observed  dips  at  the  surface  south  of  this  line 
being  N.  dips ;  and  almost  all  of  those  north  of  the  line  be- 
ing S.  dips;  the  exceptions  in  both  cases  must  be  ascribed 
to  local  crumpling.* 

*  Frazer's  Report  03,  1880,  page  58,  59.  This  description  in  the  text  does 
not  exactly  consist  with  the  hypothetical  curves  of  the  N.  and  8.  long  sec- 
tion from  Neffsville  through  Lancaster  to  Martin ville  published  in  Atlas  to 
C3.  The  section  was  drawn  subsequently  after  a  careful  discussion  of  the 
surface  dips,  and  shows  two  deep  basins,  instead  of  one;  the  northern  basin 
being  under  the  city  and  of  great  depth  ;  the  southern  basin  being  south  of 
the  city,  not  so  deep,  and  with  a  broad  rolling  bed  line.  But  geologists  who 
had  dealt  much  with  a  folded  country  will  appreciate  the  difficulties  in  the 
way  of  an  even  approximately  correct  underground  construction  of  curves 
based  on  surface  dips  most  of  which  have  angles  between  60°  and  90°  and 
many  of  them  probably  overturned.  The  section  has  the  merit  of  corres- 
ponding to  the  two  synclinal  limestone  belts  which  cross  the  Susquehanna, 
one  at  Columbia,  the  other  some  miles  lower  down.  See  the  colored  geolog- 
cal  map  of  Lancaster  county  in  Atlas  to  C3. 


486  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

The  Lancaster  section  is  described  by  Dr.  Frazer  in  a 
most  interesting  manner  in  detail  on  pp.  145  to  158  of  Re- 
port C3.  The  object  of  the  section  was  to  obtain  the  thick- 
ness of  the  formation  and  its  depth  beneath  the  city  of 
Lancaster.* 

Dr.  Frazer  remarks  that  the  dips  seem  to  require  one 
complete  synclinal  and  one  and  a  half  anticlinals,  between 
the  northern  Lancaster  township  line  and  the  Conestoga 
where  the  section  line  crosses  it.  Two  points  in  the  city 
are  indicated  where  the  limestone  bottom  is  nearest  the 
present  surface,  one  just  south  of  the  north  city  line,  the 
other  between  Conestoga  and  Hazel  streets  ;  but  the  depth 
cannot  be  measured  on  account  of  the  high  loops  which  the 
strata  make,  and  the  slip  of  bed  on  bed.  He  then  uses  an 
ingenious  mathematical  (geometrical)  rule  discussion  (p.  150) 
and  concludes  that  it  is  only  safe  to  say  that  the  total 
thickness  of  the  limestone  measures  before  erosion  in  the 
vicinity  of  the  P.  RR.  station  was  not  less  than  2700  feet. f 

*  The  section  was  started  as  far  north  as  Neffsville  because  the  lowe 
slates  there  come  to  the  surface  (with  fragments  of  Chikis  quartzite)  and 
continue  at  the  surface  for  1000'.  A  limestone  quarry  is  crossed  250'  further 
south.  At  1600'  a  L.  crop  dips  about  E.  showing  how  crumpled  the  country 
must  be.  At  1|  m.  pale  limestone  dips  only  6°,  S.  20°  E.  Close  by,  a  quarry 
reads  20°  S.  Then  one  reads  20°  N.  Then  500'  further  60°  N.  W.  Another 
24°,  N.  20°  W.  At  Myers'  quarry  a  quartz  seam  18°  N.  '  All  this  indicating 
the  N.  side  of  a  gently  sloping  anticlinal ;  the  same  is  indicated  for  3500 
further.  At  Dillersville  a  RR.  dip  reads  38°,  S.  15°  E.  which  seems  to 
begin  the  descent  of  the  beds  on  the  S.  slope  of  the  anticlinal ;  soon,  50°.; 
35°,  S.  25°  E.  Then  a  synclinal;  for,  at  the  divergence  of  the  P.  RB.  and 
R.  RR.  is  seen  an  (overturned)  dip  of  80°,  S.  15°  E.  (Another  before  cross- 
ing the  township  line,  75°,  S.  15°  E.)  Then  in  Lancaster  township  80°,  S. 
150  E.  Then  the  south  side  of  the  anticlinal,  500'  from  last,  30°  S.  Where 
the  two  RRs.  cross,  70°,  S.  15°  E.  In  the  cut  just  E.  of  Lancaster  station, 
67°,  S.  15°  E.  No  exposures  for  500'.  Where  Vine  street  crosses  the  Quar- 
ryville  RR.,  70°,  S.  5°  W.,  continued  for  165'  to  the  Soap  Factory;  the 
rocks  turning  gradually  into  a  curly  hydromica  schist,  showing  that  the 
bottom  beds  of  the  formation  here  rise  again  to  the  surface.  And  so  the 
record  of  the  section  runs  on  southward. 

f  From  the  Conestoga  south  to  Mill  creek  the  details  of  the  section  are 
narrated  and  the  conclusion  reached  that  the  whole  series  of  minor  anti- 
clinal and  synclinal  rolls  are  crossed.— Between  Mill  creek  and  D.  Harnish's 
house,  5  minor  anticlinals,  the  whole  body  of  measures  rising  southward. — 
Then  a  gap  in  the  record  of  4400'  near  the  middle  of  Pequea  township.— The 
southern  portion  of  the  section  is  extraordinarily  difficult  of  construction, 
as  both  mica  slate  and  gneiss  exposures  occur  in  it.  See  C3,  pp.  156  et  seq. 


THICKNESS   OF   NO.    II.  487 

This  deep  basin  extends  from  the  Salisbury  cove  in  the 
mountain  land  of  Chester  county  westward  across  Lancaster 
county  ;  and  beyond  the  river  is  continued  as  the  York 
county  limestone  valley  to  Adams  county. 

Another  equally  deep  basin  runs — the  Conestoga  valley — 
north  of  it,  parallel  with  it,  from  the  Berks  county  corner, 
westward,  to  the  Susquehanna  above  Marietta,  and  so  into 
York  county. 

Many  other  smaller  basins  cross  Lancaster  'county,  ob- 
scurely, in  a  parallel  series,  the  exact  shapes  of  which  can- 
not possibly  be  made  out  from  surface  dips,  because  there  are 
no  well  denned  characteristic  marks  to  distinguish  the  lime- 
stone beds  from  one  another;  and  all  the  basins  are  so  con- 
nected sideways  with  each  other  that  the  strata  pass  over 
the  upfolds  from  one  basin  to  the  next ;  the  whole  being 
eroded  to  a  general  plane  surface.* 

The  most  southern  basin  which  has  preserved  its  lime- 
stone rocks  is  that  of  the  Chester  county  valley;  and  this 
deepens  eastward,  and  then  shallows  to  its  end  in  Mont- 
gomery county.  The  widest  and  probably,  therefore, 
deepest  part  of  this  Chester  county  valley  is  between  Down- 
ingtown  and  the  Schuylkill;  but  the  beds  are  so  complicated 
by  longitudinal  anticlinal  and  synclinal  waves,  as  shown 
in  the  sections  on  plates  45,  46,  47,  that  it  is  impossible  to 
calculate  with  any  approach  to  accuracy  the  thickness  of 
the  formation  which  remains  at  the  present  day,  to  say 
nothing  of  its  original  thickness  before  the  erosion  of  the 
contents  began  to  remove  from  over  it  the  slate  formation 
of  No.  III.  At  least  2000'  and  perhaps  3000'  of  it  still  re- 
main. It  may  have  been  as  thick  as  it  is  in  Centre  county; 

*  There  can  be  no  reasonable  doubt  that  the  Azoic  country  of  southern 
Lancaster,  southern  Chester  and  Delaware,  on  the  one  hand,  and  southern 
York  and  eastern  Maryland  on  the  other  hand,  were  each  and  all  once  cov- 
ered with  the  Lancaster  limestone  formation  II.  Nor  can  any  reason  be  as- 
signed why  the  formation  as  a  whole  should  not  have  been  formerly  as 
many  thousand  feet  thick  in  its  extension  to  the  Atlantic,  as  it  is  now  seen 
to  be  at  Lancaster  and  Harrisburg.  Its  great  thickness  at  York,  at  Lan- 
caster and  at  Downingtown  is  an  absolutely  satisfactory  guarantee  of  its 
ancient  unbroken  extension  southeastward  over  the  present  Atlantic  coast 
region. 


488  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

but  that  is  not  probable;  for  there  is  no  part  of  the  Great 
Valley  in  which  such  a  thickness  can  be  proven. 

In  the  Great  Valley  we  have  also  everywhere  an  exces- 
sive complication  of  the  limestone  strata  of  No.  II.  There  is 
no  section  from  the  Delaware  at  Easton  to  the  Potomac  in 
Maryland  where  a  fair  and  unimpeachable  measurement 
of  the  formation  can  be  made;  and  the  faulting  along  the 
southern  edge  of  the  Great  Valley  prevents  us  from  even 
estimating  the  amount  which  has  been  removed  by  erosion. 
Two  or  three  thousand  feet  of  limestone  strata  are  evidently 
present  at  the  surface;  how  much  more  we  cannot  tell. 

In  the  coves  and  valleys  of  middle  Pennsylvania  most  of 
the  formation  is  concealed  underground.  In  Nittany  valley 
alone,  along  the  Little  Juniata  river  has  a  good  opportunity 
been  granted  to  measure  the  formation,  and  even  here  not 
quite  to  its  base  at  Birmingham.  But  the  locality  is  most 
favorable  to  the  inquiry.  From  the  Canoe  mountain  syn- 
clinal to  the  Nittany  anticlinal  the  dips  'are  all  one  way  and 
the  sequence  apparently  unbroken.  This  noble  section  has 
been  repeatedly  criticized  and  measured  with  the  greatest 
care;  first  by  Mr.  Rogers  in  the  First  Survey,  and  lastly  by 
Mr.  Platt  and  Mr.  Sanders  in  the  topographical  survey  of 
the  Blair  county  region,  published  (text  and  sheet  map)  in 
Report  T,  and  Atlas.  On  the  basis  of  this  survey,  which 
took  account  of  all  the  dips  of  all  the  exposed  rocks  along 
the  river  on  both  sides  of  the  Canoe  mountain  synclinal, 
there  were  counted  up  6600';  subdivided  thus  :  Upper  lime- 
stone series,  5400';  Middle  white  sandstone  beds,  40';  Lower 
limestone  series,  including  some  sandy  or  sandstone  layers 
at  bottom  which  may  belong  to  the  Chiques  (Cambrian) 
quartzite  system,  1160' =6600' .* 

*T,  p.  52.  Mr.  Sanders  has  measured  3000'  of  consecutive  layers  at  Har- 
risburg.  Mr.  Prime  measured  only  2000'  at  Allentown.  In  Report  O,  Vol. 
I,  of  the  catalogue  of  the  Geol.  Museum,  1878,  p.  1J3,  is  given  a  list  of  240 
specimens  collected  from  the  outcrops  of  II  along  the  Little  Juniata  from 
Tyrone  Gap  down  to  Spruce  Creek.  These  are  summarized  in  T,  page  58. 
These  collections  by  Mr.  C.  E.  Hall  show  an  extraordinary  dearth  of  fossils 
in  the  formation;  but  Trenton  and  Calciferous  New  York  forms  were  cer- 
tainly identified.  Mr.  Hall  remarks  on  the  special  steepness  of  the  dips,  and 
on  the  fact  that  the  dips  do  not  correspond  well  on  the  two  sides  of  the  river 
(T,  p.  59). 


THICKNESS   OF   NO.    II.  489 

When  the  limestone  formation  No.  II  sinks  at  the  foot  of 
Bald  Eagle  mountain  it  does  not  rise  again  to  the  surface 
for  100  miles,  to  the  Mohawk  valley,  in  New  York.  The 
depth  to  which  its  uppermost  division,  the  Trenton,  He, 
sinks  beneath  the  highlands  of  Lycoming  county  is  15,000 
feet.* 

After  the  developments  of  gas  and  oil  in  the  Trenton 
limestone  in  western  Ohio  and  in  Indiana  a  large  number  of 
wells  were  bored  in  northern  Ohio,  in  Upper  Canada  and 
in  western,  middle  and  eastern  New  York  to  test  the  oil  and 
gas  value  of  the  formation  along  the  belt  of  country  where 
it  was  known  to  lie  undisturbed  and  not  too  deeply  cov- 
ered to  be  reached  at  reasonable  rates  of  expense,  say  3000' 
or  4000'  feet  beneath  the  surface. f 

At  Ithaca,  N.  Y.,  a  test  well  (in  the  valley)  said  to  be 
3185'  deep,  stopped  in  the  middle  of  formation  No.  V,  and 
should  have  gone  down  to  4755'  to  reach  the  top  of  the 
Trenton.:}: 

From  Ithaca  northward  the  rise  is  very  gradual  to  the 
outcrop  of  the  top  of  the  formation  at  Trenton  Falls  where 
the  upper  division  of  No.  II  got  the  name  in  1835  which  it 
has  retained  to  the  present  day.  It  is  quarried  along  the 
banks  of  the  Mohawk,  south  of  which  it  is  covered  by  the 

*  As  measured  by  Dr.  Chance,  in  Clinton  county,  Lock  Haven  long  sec- 
tion, Report  G4,  p.  124.  Its  depth  beneath  Cresson,  or  Ebensburg,  in  Cam- 
bria county,  according  to  the  section  by  Platt  and  Sanders  (Appendix  A  to 
Report  F,  p.  262)  is  about  17,000'.  Its  depth  beneath  the  Mountain  House  on 
Broad  Top  in  Huntingdon  county  is  nearly  18,000'  (see  F,  p.  184).  Between 
the  tost  two  mentioned  depths  it  rose  into  the  air  over  Birmingham  6000'. 
The  Nittany  valley  anticlinal  was,  therefore,  a  rock  wave  25,000'  or  26,000', 
i.  e,  5  miles,  high. 

t  These  borings  have  greatly  enlarged  and  improved  our  knowledge  of  the 
Palaeozoic  formations,  especially  as  to  their  varying  thicknesses,  and  as  to  their 
condition  and  quality  beneath  different  sections  of  country.  The  bore-hole 
records  have  been  discussed  very  skilfully  by  the  late  C.  A.  Ashburner,  and 
by  Prof.  Prosser,  of  Ithaca,  N.  Y.,  now  of  the  U.  S.  Geol.  Survey  at  Wash- 
ington.- The  facts  thus  obtained  will  be  frequently  used  in  subsequent 
chapters  of  this  report. 

J  C.  S.  Prosser,  "  The  thickness  of  the  Devonian  and  Silurian  rock  of  west- 
ern central  New  York,"  in  the  Amer.  Geologist,  Oct,  1890,  p.  202,  211.  The 
estimates  from  data  furnished  by  the  Syracuse  well  would  make  the  depth 
5172';  the  estimate  from  maximum  thicknesses  in  general  section  would 
make  it  5708'. 


490  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

Hudson  river  and  Utica  slates  of  III,  3500'  thick,  through 
part  of  which  the  Knowersville  gas  test  well,  3000'  deep, 
went  down  and  penetrated  the  upper  120'  of  the  Trenton, 
to  which  Ashburner's  Catskill  section  assigns  a  total  of 
500.'* 

The  Wolcott  well,  in  Wayne  county,  N.  Y.,  on  the  south 
border  of  Lake  Ontario  struck  the  top  of  the  Trenton  at  a 
depth  of  1950',  and  stopped,  still  in  Trenton  limestone,  at 
2700'.  When  it  is  remembered  that  the  greatest  depth  of 
the  lake  near  its  southern  shore  is  about  700',  we  can  under- 
stand the  true  formation  of  the  great  valley  of  erosion  in 
which  its  waters  are  held — a  valley  excavated  in  very  an- 
cient times  by  the  chemical  solution  of  the  great  limestone 
formation  No.  II,  and  the  mechanical  removal  of  the  over- 
lying slates  of  III  and  sandstone  of  IV  (Oneida  and  Medina) 
the  outcrop  of  which  makes  its  steep,  half  submerged  south- 
ern shore,  f 

Onr  better  knowledge  of  a  greater  thickness  of  II  and 
III  in  the  Mohawk  country  than  has  hitherto  been  allowed 
them  is  very  satisfactory  on  the  score  of  bringing  their 
distinct  areas  into  closer  harmony  with  their  great  exhibi- 

*  Petroleum  and  Natural  Gas  in  New  York  state.  C.  A.  Ashburner,  Trans. 
Amer.  Int.  Min.  Eng.  Duluth  meeting,  July,  1887,  foot-note  to  page  49  of 
paper.  For  geologists  the  record  of  this  well  is  uncommonly  valuable, 
greatly  increasing  the  traditional  thickness  of  III.  to  which  in  W.  New 
York  only  800'  to  1000',  and  on  Georgian  bay  in  Canada  only  770',  was  as- 
signed. The  Utica  in  Montgomery  county,  N.  Y.  west  of  Albany,  has  been 
called  250';  but  the  Campbell  well  west  of  Utica  went  through  710'  of  it, 
Walcott  calls  its  outcrops  on  the  Mohawk  600'.  As  to  the  Trenton,  Vanuxem 
only  gave  it  300'  in  Lewis  county.  Emmons  made  it  400'.  In  Canada 
Logan  measured  679'  and  750'.  Walcott  makes  it  in  the  Campbell  well  near 
Utica  430'  and  the  surface  outcrops  290'  (Proc.  A.  A.  A.  S.  Vol.  36,  p.  212). 
Prosser  gives  a  general  thickness  of  820'  to  III,  and  992'  to  II  (Trenton  842'- 
Calc.,  150'). 

t  Lake  Ontario,  if  drained  of  its  water,  would  be  a  repetition  of  our  Great 
Valley,  with  the  difference  that  the  two  formations  II  and  III  lie  almost  flat 
and  undisturbed  instead  of  being  crumpled  and  crushed ;  the  limestone 
(II)  rising  northward  out  of  the  water,  and  constituting  the  great  plain  of 
the  St.  Lawrence.  It  must  be  understood  that  Ontario  has  been  considera- 
bly refilled  by  glacial  deposits,  etc.,  since  its  submergence.  Its  old  bed  is 
far  deeper  than  its  present  bed,  probably  2000',  and  was  originally  deeper 
towards  the  northern  shore  than  towards  the  southern.  This  also  irrespec- 
tive of  the  tilt  which  it  has  suffered  in  recent  times. 


THICKNESS   OF   NO.    II.  491 

tions  in  Middle  Pennsylvania  ;  and  also  in  another  respect, 
namely,  by  adding  one  more  line  of  evidence  for  their 
identity  with  the  so-called  Taconic  limestones  and  slates  of 
the  western  border  land  of  New  England.  For  it  is  incred- 
ible that  4500'  of  II  and  III  should  exist  15  miles  west  of 
Albany,  and  not  be  well  represented  in  the  Taconic  region 
east  of  Albanv. 


492  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 


CHAPTER  XLII. 
Oil  and  Gas  in  No.  II. 

Dr.  Orton  says  that  the  Trenton  limestone  when  followed 
northward  both  in  Ohio  and  Indiana  suffers  a  transforma- 
tion through  a  small  thickness  of  its  upper  beds,  by  these 
upper  beds  losing  their  pure  limestone  character  and  be- 
coming dolomitic  or  magnesian  ;  and  that  this  change 
affects  frorn  10'  to  50'  of  strata  at  the  top  of  the  formation  ; 
perhaps  in  rare  instances  100  feet.  Generally  the  wells 
passed  through  magnesian  limestone  from  the  very  top  of 
the  formation  downward  ;  but  in  some  cases  pure  limestone 
is  found  at  the  top  of  the  formation  over  the  magnesian 
strata ;  and  in  every  such  instance  the  magnesian  lying 
directly  upon  the  pure  limestone.* 

The  line  along  which  the  change  from  limestone  to  dolo- 
mite occurs,  passes  through  Hancock,  Allen  and  Mercer 
counties  southwesterly  into  Indiana,  and  so  onward  through 
Jay,  Randolph  and  Henry  into  Indiana ;  and  this  is  the 

*  Dr.  Orton's  language  implies  a  theory  that  the  formation  was  originally 
pure  limestone,  and  has  been  partially  changed  to  dolomitic  limestone  by 
the  introduction  of  magnesia;  for  he  adds,  "In  other  words  the  change  is 
comparatively  superficial,"  and  he  speaks  of  "normal  or  unaltered  lime- 
stone." This  theory  is  much  in  vogue  among  European  geologists,  although 
it  is  also  strongly  opposed.  In  Pennsylvania  the  theory  has  been  com- 
pletely broken  down  by  the  statement  of  facts  narrated  in  Chapter  XXVIII, 
p.  327  above. 

In  Pennsylvania  the  Trenton  limestone  as  a  formation  and  judging  from 
a  very  insufficient  series  of  analyses  of  specimens  collected  at  hazard  in 
different  parts  of  the  State,  has  been  called  a  pure  or  non-magnesian  lime- 
stone ;  but  our  knowledge  of  its  chemical  composition  is  still  extremely 
limited,  and  the  only  safe  assertion  which  can  be  made  respecting  it  is,  that 
as  a  formation  hundreds  of  feet  thick  it  contrasts  in  a  general  way  with  the 
great  limestone  formations  under  it  (Calciferous)  in  being  less  magnesian. 
I  have  no  doubt,  however,  that  if  many  thousands  of  analyses  of  Trenton 
specimens  from  the  extensive  outcrops  in  Pennsylvania  were  made  and 
compared  it  would  be  discovered  that  the  formation  contained  locally 
magnesian  beds,  in  other  words,  that  the  same  phenomenon  described  by 
Dr.  Orton  in  the  gas  fields  of  Ohio  and  Indiana  would  recur  in  various 
places  in  Pennsylvania. 


OIL   AND   GAS   IN   NO.    II.  493 

boundary  of  the  new  gas  and  oil  fields.  Bur  in  Ohio  it/ex- 
tends  from  the  present  gas  and  oil  fields  northward  and 
westward  ;  and  patches  are  sometimes  found  to  the  north- 
eastward. In  Indiana  it  appears  to  extend  to  the  northern 
and  northwestern  boundaries  of  the  State  ;  and  is  presumed 
to  underlie  the  entire  peninsula  of  Michigan,  on  the  strength 
of  a  few  analyses  from  borings  in  that  State. 

The  porosity  of  the  rock  is  supposed  to  be  connected  in 
some  way  with  its  charge  of  magnesia.* 

*Dr.  Orton  says,  "To  be  a  reservoir  of  oil  or  gas  the  upper  surface  of  the 
Trenton  limestone  must  have  suffered  the  dolomite  replacement,  whereby 
due  porosity  has  been  conferred  upon  it,  and  it  must  also  have  received  in 
the  accidents  of  its  history  the  due  relief  by  which  its  varied  contents  have 
been  separated  and  accumulated,"  but  if  the  magnesian  limestone  was  not 
introduced  afterwards  but  was  a  part  of  the  original  deposit,  the  porosity  of 
the  rock  must  be  explained  by  the  superior  solubility  of  the  magnesian  car- 
bonate above  the  lime  carbonate.  It  is  strange  that  in  the  abundant  litera- 
ture on  this  subject  so  little  notice  is  taken  of  the  presence  of  salt  water  in 
the  porous  rock  at  the  lower  limit  of  the  oil  and  gas  belt ;  at  what  is  called 
the  dead-line  in  the  Findley  field.  This  dead-line  in  the  Findley  field 
follows  the  hypsometric  line  of  500'  below  sea  level ;  every  well  which 
strikes  the  Trenton  limestone  at  this  level  or  at  lower  levels  has  found  the 
rock  charged  mainly  with  salt  water.  In  the  Lima  field  a  similar  dead-line 
400'  or  more  below  sea  level  has  salt  water  on  the  southwest  of  it,  and  oil 
and  gas  on  the  northeast  of  it ;  the  productive  wells  striking  the  limestone 
at  from  390'  to  350'  below  sea  level.  In  Indiana  the  dead  or  salt  water  line 
surrounds  the  productive  territory  on  the  north  and  west  at  only  100'  below 
sea  level.  The  limestone  gradually  rising  southward  without  any  anticli- 
nal or  terrace  structure,  the  gas  production  ceases  abruptly  and  without 
any  apparent  reason.  Dr.  Orton  proposes  as  a  probable  explanation  for  this 
fact  the  change  of  the  formation  from  dolomitic  porous  limestone  to  pure 
tight  limestone ;  but  in  doing  this  he  virtually  discards  the  reason  given 
for  the  upper  limit  of  gas  production  in  the  Findlay  and  Lima  regions, 
namely,  an  anticlinal  or  rather  a  terrace  structure. 

I  have  just  said  that  it  is  strange  to  notice  in  the  literature  of  the  subject 
a  prevailing  indifference  to  the  value  of  the  fact  of  the  universal  presence  of 
salt  water  below  the  dead  line.  Surely  some  explanation  of  the  existence 
of  that  salt  water  must  be  taken  into  the  theory.  First,  a  question  arises  re- 
specting the  age  of  that  saltwater.  Is  it  the  original  sea  water  in  which  the 
Trenton  limestone  was  deposited  ?  if  not,  is  it  salt  water  which  has  pene- 
trated from  any  ocean  past  or  present?  if  not,  is  it  analogous  to  the  salt 
water  of  closed  basins,  seas  or  lakes  which  have  no  outlet?  in  other  \\ords, 
has  the  rain  water  obtained  salt  from  salt-bearing  formations  and  collected 
as  salt  water  in  this  Trenton  reservoir?  if  not,  does  the  saltin  this  saltwater 
represent  an  original  element  of  the  formation  itself,  namely,  a  certain 
charge  of  chloride  of  sodium  deposited  originally  with  the  carbonate  of  lime 
and  carbonate  of  magnesia ;  and  subsequently  through  the  ages  dissolved 
out  by  the  percolating  rain  water,  which  has  ever  since  held  it  in  solution  ? 


494  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

Why  no  Trenton  oil  or  gas  in  Pennsylvania. 

To  the  people  of  Pennsylvania  the  practical  question  is 
simply  this :  Does  the  Trenton  limestone  formation  in  Penn- 
sylvania hold,  and  will  it,  if  bored  down  to,  furnish  a  future 
supply  of  oil  or  gas,  or  both,  to  supplement  the  rapidly  ex- 
hausting oil  and  gas  pools  in  the  Devonian  oil  sands  of  the 
western  counties  ?  The  answer  is : 

Certainly  not  in  southeastern  Pennsylvania. 

Certainly  not  in  middle  Pennsylvania. 

Probably  not  in  the  rest  of  the  State. 

if  so,  such  dissolvine  out  of  original  crystals  of  salt  has  of  itself  played  a 
certain  part  in  the  production  of  the  porosity  of  the  rock.  The  above  are 
important  questions  which,  so  far  as  I  know,  have  never  been  properly 
presented,  much  less  answered.  And  their  range  of  application  in  geology 
far  exceeds  the  limits  of  oil  and  gas  regions  ;  in  fact,  take  in  all  brine  regions. 

We  know  little  enough  of  the  methods  of  nature  in  past  time  as  to  the  de- 
posit of  sandstone  strata  ;  but  we  know  far  less  respecting  the  mode  of  an- 
cient limestone  deposits,  under  conditions  of  topography  and  climate  so 
different  from  anything  we  now  see  that  arguing  from  the  present  to  the 
past  is  almost  impossible.  The  present  river  drainage  of  the  world  carries 
chiefly  clastic  detritus :  that  is,  most  of  the  land  being  destroyed  by  rain- 
water and  transferred  to  sea  bottom  has  already  undergone  that  process 
once  or  many  times.  But  in  the  Lower  Silurian  Age  it  is  reasonable  to  be- 
lieve that  the  larger  part  of  the  land  consisted  of  crystalline  rock  and  fur- 
nished by  its  own  river  drainage  a  very  different  kind  of  material  to  a  sea 
much  warmer,  perhaps  hot,  in  which  chemical  re-actions  took  place  on  the 
grandest  scale.  Dr.  T.  S.  Hunt  has  endeavored,  and  with  much  success,  in 
suggesting  a  picture  of  the  operations  of  that  ancient  time  ;  or  rather  of  a 
time  far  more  ancient  when  chemical  precipitation  was  probably  almost  the 
only  form  of  ocean  deposit.  The  Lower  Silurian  Age  indeed  stands  midway 
between  the  first  age  of  nearly  pure  chemical  precipitation  and  a  percentage 
of  almost  pure  mechanical  deposit ;  and  it  therefore  ought  to  represent  by 
the  nature  of  its  rocks  both  kinds  of  operation,  intermingled  indeed  in  a 
manner  to  confuse  very  completely  geological  judgment. 

Dr.  Hunt's  crenitic  hypothesis  (cr6n6,  a  fountain)  is  an  admirable  attempt 
to  solve  the  first  great  difficulty  in  geology,  namely,  the  source  of  those  ele- 
ments, alumina,  lime,  magnesia,  soda,  potassa  and  iron,  which  make  up  al- 
most the  whole  crust  of  the  earth.  Oxygen  and  chlorine  holding  these  ele- 
ments in  solution  were  of  course  in  ancient  times  part  of  the  earth's  atmos- 
phere. The  basis  must  have  resided  in  the  globe  either  pure  or  alloyed  in 
mutual  combination,  but  certainly  not  except  under  the  condition  of  very 
high  heat.  The  union  of  the  gases  with  them  must  have  marked  the  grad- 
ual cooling  of  the  globe.  But  the  first  rivers  must  have  been  not  only  hot 
water,  but  mineral  water ;  and  the  first  deposits  must  have  been  chemical 
precipitates.  To  state  the  case  transcendentally,  we  may  imagine  (what  of 
course  never  happened  in  exactly  that  way)  three  rivers  pouring  three  kinds 
of  mineral  water  into  a  closed  basin  resulting  in  a  sea ;  one  discharging  a 
solution  of  lime  chloride  ;  a  second,  a  solution  of  soda  carbonate  ;  the  third, 
a  solution  of  magnesia  sulphate.  The  common  tank  would  become  filled 


OIL   AND   GAS   IN  NO.    II.  495 

And  for  the  following  reasons:  (1)  An  oil  rock  must  be 
porous,  but  not  broken  up;  (2)  it  must  lie  Hat,  and  have  a 
good  covering;  (3)  it  must  not  be  too  deep  beneath  the  sur- 

with  these  three  solutions  interfused;  not  homogeneously  throughout -the 
tank,  but  with  every  variety  of  interfusion  in  different  parts  of  it  according 
to  the  respective  sizes  of  the  rivers  and  the  sea  currents  which  brought  their 
infusions  together  ;  so  that  an  infinite  variability  of  chemical  precipitation 
would  result  in  all  parts  of  the  sea  bottom.  Laboratory  experiments  will 
certainly  not  teach  the  whole  story,  but  will  indicate  certain  main  facts,  the 
first  one  being  that  a  reaction  would  take  place  betweeen  the  river  of  lime 
chloride  and  the  river  of  soda  carbonate  ;  the  chloride  leaving  the  lime  and 
uniting  with  the  soda  to  make  salt ;  the  carbonate  leaving  the  soda  to  unite 
with  the  lime,  making  limestone;  and  the  magnesia  also  becoming  a  car- 
bonate with  different  solubility,  but  precipitated  in  like  manner. 

Of  course  such  a  case  as  this  is  purely  hypothetical  and  certainly  could  not 
have  occurred  in  Lower  Silurian  times,  because  life  had  already  long  ex- 
isted ;  vast  amounts  of  carbonic  acid  and  oxygen  had  already  been  ab- 
stracted trom  the  atmosphere ;  the  waters  were  cool  enough  to  permit  mollus- 
can  and  articulate  life,  as  well  as  vegetation  ;  and  the  rivers  had  long  been 
pouring  clastic  material,  gravel  sand  and  mud  into  the  sea.  Nevertheless, 
even  at  that  late  day,  compared  with  the  still  more  ancient  times,  the  rivers 
must  have  been  to  a  considerable  extent  of  the  nature  of  mineral  water  ;  and 
therefore  necessarily  the  sea  was  continuing,  although  in  a  very  moderate 
degree,  its  chemical  precipitations ;  the  lime  and  magnesia  carbonates  play- 
ing the  chief  role  ;  but  evaporation  being  still  probably  intense,  the  chemi- 
cal precipitation  of  sea  salt  must  have  played  a  part  in  the  drama  of  depo- 
sition, and  has,  in  fact,  continued  to  do  so  through  all  ages  from  that  to  the 
present  time.  Hence  all  geological  strata  contain  an  amount  of  salt ;  and  all 
atmospheric  drainage  through  geological  strata  find,  dissolve  and  bring  to 
the  surface  amounts  of  this  salt.  But  I  have  in  another  place  drawn  atten- 
tion to  the  remarkable  fact  that  soda  is  almost  absent  from  our  limestone 
strata  ;  a  fact  which  makes  it  almost  necessary  to  find  the  region  of  the  salt 
water  in  the  Trenton  formation  outside  of  it,  that  is,  in  some  of  the  more 
decided  salt-bearing  sandstones. 

The  facts  are  thus  stated  by  Dr.  T.  S.  Hunt  in  his  standard  work,  Mineral 
Physiology,  1886,  page  168.  "  The  recent  precipitate  produced  by  a  solution 
of  carbonate  of  soda  in  chloride  of  calcium  is  readily  soluble  in  an  excess  of 
the  latter  salt,  or  in  a  solution  of  sulphate  of  magnesia.  The  transparent, 
almost  gelatinous  magma  which  results  when  solutions  of  carbonate  of  soda 
and  chloride  of  calcium  are  first  mingled,  is  immediately  dissolved  by  a 
solution  of  sulphate  of  magnesia  ;  and  by  operating  with  solutions  of  known 
strength  (titrated  solutions)  it  is  easy  to  obtain  transparent  liquids  holding 
in  a  litre,  besides  three  or  four  hundredths  of  hydrated  sulphate  of  mag- 
nesia, 0.80  gramme,  and  even  1.20  grammes  of  carbonate  of  lime,  together 
with  1.00  gramme  of  carbonate  of  magnesia;  the  only  other  substance  pres- 
ent in  the  water  being  the  chloride  of  sodium  equivalent  to  these  carbonates. 
A  solution  of  chloride  of  magnesium,  holding  some  chloride  of  sodium  and 
sulphate  of  magnesia  in  like  manner  dissolved  1.00  gramme  of  carbonate  of 
lime  to  the  litre.  Such  solutions  have  an  alkaline  reaction."  [Quoted 
from  Hunt's  Chem.  and  Geol.  Essays,  page  223.] 


496  GEOLOGICAL, SURVEY   OF   PENNSYLVANIA. 

face  of  the  earth;  (4)  it  must  either  be  itself  very  fossilifer- 
ous,  or  be  enclosed  between  other  strata  which  are  so. 

All  of  these  conditions  are  realized  in  the  great  Trenton 
limestone  oil  and  gas  districts  of  Ohio,  Indiana  and  Ken- 
tucky; but  not  in  Pennsylvania. 

For  (1)  in  the  southeast  region  of  our  State  the  Trenton 
has  been  broken  and  crushed  arid  recemented,  so  as  to  be 
nowhere  porous  enough  to  hold  oil  or  gas;  (2)  in  the  middle 
region  all  the  formations  are  upturned  and  solidified  by  pres- 
sure; (3)  in  the  western  and  northern  regions,  the  Trenton 
lies  buried  10,000  to 20, 000  feet  beneath  the  present  surface, 
and  at  temperatures  between  200°  and  400°  Fahrenheit ;  and 
(4)  where  it  shows  itself  at  the  surface  in  the  middle,  south- 
ern and  eastern  counties  it  is  remarkably  poor  in  animal 
and  vegetable  remains. 

Consequently,  all  attempts  to  obtain  oil  or  gas  from  the 
Pennsylvania  Trenton — and  such  attempts  have  been  made 
Chester,  in  Montgomery,  in  Berks,  in  Danphin,  in  Hunt- 
ingdon, in  Pike,  in  Susquehannaandin  Erie  conn  ties — have 
failed. 

In  the  deep  Erie  well  the  Trenton  was  reached.  In  the 
Canada  well  on  the  south  shore  of  Lake  Ontario  near  the 
Welland  canal,  the  Trenton  was  pierced.  Several  wells  in 
New  York  State  penetrated  it.  In  no  case  has  there  been 
a  profitable  return  of  either  oil  or  gas.  And  if  this  hap- 
pened under  the  exceptionally  good  conditions  in  central 
and  western  New  York,  where  the  formation  is  very  fossil  - 
iferous,  lies  nearly  flat,  and  can  be  easily  reached,  what 
chance  is  there  of  success  for  those  who  bore  in  the  uptilted 
and  dislocated  and  poorly  fossiliferous  strata  of  Pennsyl- 
vania ?  Where  the  Trenton  is  brought  to  the  surface  it 
shows  plainly  that  whatever  petroleum  or  rock  gas  was  once 
distilled  from  its  fossil  corals  and  shells  has  ages  ago  escaped 
from  it;  as,  and  for  the  same  reasom  that,  the  gas  of  the 
once  bituminous  coal  beds  of  Schuylkill  county  has  escaped 
from  them,  leaving  them  in  the  condition  of  anthracite. 

On  the  other  hand,  who  can  hope  for  a  time  when  oil  and 
gas  wells  can  be  sunk  to  a  depth  of  ten  or  twenty  thousand 
feet,  where  the  Trenton  may  possibly  retain  what  oil  and 
gas  it  has  at  the  boiling  point  of  water  or  even  at  400°  F. 


MECHANICAL   DEPOSITS   OF  NO.    II.  497 


CHAPTER  XLIII. 
Mechanical  deposits  of  No.  II. 

Ripple  marks  "  on  a  superb  scale  "  were  seen  on  the  sur- 
faces of  the  limestone  beds  at  the  quarry  close  to  Uhlers- 
ville,  on  the  Delaware  river,  in  Northampton  county,  by 
Prof.  Rogers.*  If  there  was  no  mistake  in  interpreting  the 
undulations  as  ripple  marks,  if  they  were  not  the  effects 
of  subsequent  pressure,  and  if  ripple  marks  are  to  be  taken 
as  a  sure  indication  of  wave-action  in  shallow  water,  then 
the  deep  sea  chemical  theory  of  the  formation  of  the  great 
limestone  must  be  abandoned.  And  this  particular  case  is 
all  the  more  important,  as  the  rocks  exposed  at  Uhlersville 
do  not  belong  to  the  top  (Trenton)  but  to  the  bottom  (Cal- 
ciferous)  division  of  No.  II,  overlying  the  Cinques  quartz- 
ite  so  full  of  worm  burrows  (Scolithus  linearis)  which  of 
course  imply  a  shallow  sandy  shore.  In  Vermont,  Brain- 
ard  and  Seely  report  the  whole  Calciferous  formation  full 
of  Scolithus,  especially  some  of  the  fine-grained  sandstone 
layers  of  the  middle  division  (C)  which  are  "pin-holed  with 
small  worm  burrows"  (Scolithus  minutus}.  This  division 
(350'  thick)  is  made  up  of  alternations  of  sandstone  beds 
and  magnesian  limestone  beds.f 

All  this  runs  in  favor  of  the  mechanical  as  opposed  to  the 
chemical  deposit  of  the  limestone  beds  of  II,  as  argued  in 
Chapter  28,  p.  334  above,  on  the  Magnesian  limestone 
alternations  in  the  quarries  opposite  Harrisburg. 

A  peculiar  sandstone. 

The  peculiarly  sandy  nature  of  the  lower  part  of  the  great 
limestone  formation  has  already  been  mentioned.  Cases 

*Geol.  of  Pa.,  1858,  p.  242. 

f  Bulletin  Geol.  Soc.  Amer.,  vol.  1,  1890,  page  504;  quoted  in  Report  P4, 
Diet.  Foss.,  Pa.,  Vol.  3,  1890,  p.  945.  See  also  the  large  worm  burrow  Mono- 
crater  ion  lesleyi,  described  from  Lehigh  county  by  Prof.  Prime  in  Report 
D2,  1878,  p.  79,  with  figures. 

32 


498  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

of  isolated  layers  of  sandstone  are  given  in  preceding  chap- 
ters.    The  Barrens  of  Centre  county  have  been  described. 

In  Sinking  Valley,  near  Birmingham  on  the  Little 
Juniata,  a  peculiar  ferruginous  sandstone  containing  also 
traces  of  manganese  and  cobalt  occurs  in  great  abundance 
on  the  farm  of  Mr.  Galbraith.  The  rock  is  a  com  pact,  brittle, 
and  exceedingly  fine-grained  mass,  streaked  with  different 
shades  of  light-red  and  pink  and  purple,  which  variations 
it  derives  from  the  different  minerals  it  contains.  In  almost 
every  hand  specimen  are  numerous  larger  and  smaller  cavi- 
ties, the  sides  of  which  are  lined  with  minute  quartz  crys- 
tals. Some  portions  of  the  mass  are  not  unlike  calamine  ; 
but  Mr.  McCreath's  analysis  of  a  specimen  of  it  shows  that 
there  is  not  even  a  trace  of  zinc  in  its  composition.  Silica, 
94.9  ;  ox.  iron  and  alumina,  3.3  ;  ox.  mang.,  a  trace  ;  ox. 
cobalt,  0.17;  lime,  0.06;  magnesia,  0.18;  water,  1.  Being 
near  the  axis  of  the  great  anticlinal  the  beds  must  be  very 
low  in  the  series.* 

Parkesburg  artesian  well  in  II. 

At  Parkesburg,  in  the  Chester  county  valley,  an  artesian 
well  was  bored,  522'  deep,  through  very  steep-dipping  lime- 
stones near  the  bottom  of  the  series.  Not  only  sandstone 
layers  but  quicksand  layers  were  passed  through,  the  latter 
furnishing  water  (in  one  case  pretty  freely),  and  being 
probably  the  disintegrated  loose  grains  of  beds  of  calcifer- 
ous  sandstone  which  had  lost  all  their  soluble  lime  and 
magnesia  carbonates  by  long  continued  percolation.f 

*  T,  p.  291.— Mr.  Platt  in  his  Report  on  Blair  county  remarks  that  the  dis- 
tinct sandstone  horizons  in  No.  II,  in  Nittany  valley,  make  a  show  in 
boulders  and  fragments  on  the  surface  of  the  country  out  of  all  proportion 
to  their  size  as  beds  in  the  limestone  series.  But  this  is  a  common  geological 
phenomenon  of  erosion,  well  illustrated  by  the  abundance  of  quartz  boulders 
left  lying  on  the  eroded  surface  of  the  hydromica  belt  of  York  county,  and 
the  abundance  of  titaniferous  iron  ore  fragments  left  lying  on  the  off  dip 
side  of  the  veins  on  the  demoralized  mica  gneiss  country  of  Goldsboro'  in 
N.  Carolina.  As  the  surface  of  the  soluble  formation  is  lowered  by  erosion, 
the  insoluble  massive  layers  accumulate  on  the  successive  surfaces.  (Report 
T,  on  Blair  Co.,  p.  60.) 

\  Soil,  18';  bastard  or  sandy  limestone,  3';  quicksand,  2';  sandy  limestone 
growing  denser  downwards  ;  quicksand;  limestone  be"ds  increasingly  pure 
downward,  and  quite  destitute  of  water  veins ;  fine  yellow  sandstone  layer 


PAKKESBURG   ARTESIAN   WELL   IN   NO   II.  499 

To  explain  the  sand  deposits  in  No.  II  in  Pennsylvania 
we  must  go  to  northern  New  York  and  to  the  Western 
States. 

Around  the  Adirondacks  the  lowest  beds  of  the  Calcifer- 
ous  sandstone  (Ha)  of  Eaton  and  Vanuxem  are  a  mixture  of 
fine  grains  of  sand  in  a  cement  of  limestone,  with  a  few 
fossils  converted  into  chert,  30' ;  over  these,  reddish  lime- 
stone beds  with  scattered  plates  of  Cystids,  20';  over  these, 
clay  beds  without  fossils,  but  at  the  top  oolitic,  10' ;  over 
these,  red  limestones,  15';  over  these,  clay-lime  and  sand- 
lime  beds,  with  trilobites,  20';  over  these,  others  with  brach- 
iopod  shells;  over  these,  red  limestone,  with  Cystids,  fine 
enough  to  polish,  15';  over  these,  magnesian  hydraulic- lime 
beds,  with  few  fossils  except  seaweeds  (fucoids)  and  the 
upper  layers  (20  to  30')  blue,  cherty,  oolitic. 

The  Chazy  (lib)  is  so  similar  to  the  Calciferous  under  it, 
as  to  make  it  hard  to  distinguish  them.  Emmons  calls  it 
130'  thick  at  Chazy  village.  Owen  recognized  it  in  the  St. 
Peters  sandstone  along  the  banks  of  the  Minnesota  river, 
where  it  is  a  remarkably  white  mass  of  transparent  quartz 
grains,  filling  depressions  in  the  upper  surface  of  the  Calci- 
ferous, which  of  course,  had  been  out  of  water  and  eroded. 
Some  conglomerate  beds  at  the  bottom  of  the  Chazy  tell 
the  same  story.  The  Chazy  water  must  have  been  (in  Iowa 
at  least)  very  shallow,  for  there  is  plenty  of  oblique  bed- 
ding. (In  Pennsylvania,  where  these  formations  are  so 
vastly  thicker  no  such  false  or  current  bedding  is  reported.) 
Its  fossils  have  been  badly  preserved;  but  there  are  often 
plenty  of  seaweed  impressions,  worm  burrows  (Scolithus) 
and  ripple  marks;  all  proofs  of  shallow  or  shore  water. 

In  Missouri  the  sandy  character  of  No.  II  is  illustrated 
by  the  breaking  up  of  the  Calciferous  (Ha)  into  two  mag- 
nesian limestone  formations  separated  by  a  sandstone  forma- 
tion. The  Upper  Limestone  interstrated  with  shale  beds  and 

with  free  flow  of  water;  limestone  beds  (without  water)  all  of  different 
quality,  some  quite  sandy,  some  with  much  mica  flakes,  some  almost  pure 
marble ;  fissure  and  water ;  limestone  beds  as  variable  in  character  as  those 
above,  and  no  sign  of  essential  change,  or  approach  to  quartzite  at  bottom 
of  well.  In  the  samples  submitted  to  the  microscope  were  noticeable 
quartz  crystals,  mica  flakes,  crystals  of  pyrites,  of  calcite,  and  of  feldspar. 


500  GEOLOGICAL   SUKVEY   OF   PENNSYLVANIA. 

layers  of  white  chert,  with  some  thin  beds  of  white  sandstone, 
(often  lead  bearing),  is  200'  to  300'  thick.  The  Middle  Sand- 
stone regularly  bedded,  and  ripple  marked,  with  thin  chert 
layers  full  of  fossil  shells,  showing  shallow  water,  is  150' 
thick.  The  Lower  Magnesian  limestone,  thick  bedded, 
coarsely  crystalline,  with  thick  chert  beds  in  some  places, 
and  the  chief  lead  bearing  formation  of  S.  Missouri  (as  in 
Blair  county,  Pa.)  carrying  also  zinc,  copper,  nickel  and 
cobalt,  disseminated  and  also  concentrated  in  fissures  and 
caves,  ranges  in  thickness  from  300'  to  600'.  This  must  be 
a  comparatively  deep  water  deposit. 

The  geology  of  Blair,  Huntingdon,  Centre  and  Clinton 
counties  and  of  the  Great  Valley  is  greatly  elucidated  by 
the  facts  above  mentioned  a  thousand  miles  distant.  Not 
less  so  does  the  geology  of  the  Great  Valley  in  East  Ten- 
nessee explain  our  own,  for  the  resemblance  is  even  closer 
because  the  conditions  of  deposition  were  more  alike. 


THE  FOSSILS   OF   NO.  II.  501 


CHAPTER  XLIV. 

The  fossils  of  No.  II. 

In  Pennsylvania  the  Calciferous  Ila,  is  almost  non-fossil- 
iferous;  the  Chazy  II  b  is  slightly;  the  Trenton,  lie,  abund- 
antly fossiliferous,  its  best  explored  and  most  remunerative 
localities  being  Bellefonte  in  Centre  and  Reedsburg  in  Mif- 
flin  counties. 

The  Calciferous  chert  beds  maybe  taken  as  good  evidence 
of  the  abundance  of  Sponge  life.*  The  oolitic  or  fish-roe 
limestone  beds  have  recently  been  shown  under  the  micro- 
scope to  owe  their  origin  to  minute  rolled  fragments  of 
Bryozoa,  which  grew  as  parasites  upon  the  outside  of  sedent- 
ary shells,  somewhat  in  the  style  of  the  lichen  family  of 
plants  on  rocks.  Early  forms  of  Coral  grew  in  bundles  of 
prismatic  columns. f  The  Stonelilies  (crinoidea,  cystoidea) 
all  of  them  more  or  less  stemmed,  but  not  all  rooted,  have 
left  their  distracted  plates  in  the  Calciferous  of  New  York. 
The  first  Star  fish  forms  appear  in  the  Chazy.  Brachiopod 
shells,  especially  Lingula,  were  abundant  in  all  the  shallow 
waters,  but  are  not  found  in  Pennsylvania.  Lamellibranch 
shells  seem  to  make  their  first  appearance  in  the  Calciferous 
age.  Gasteropod  shells,  both  coiled  and  spired,  and  some 
like  Maclurea  magna  of  considerable  size,  were  extremely 
abundant  near  the  coasts.  Their  scarcity  in  Pennsylvania 
argues  for  depth  of  watei'4  CepTialopod  (cuttle-fish)  free 

*  Sir  Wm.  Dawson  has  given  us  their  forms ;  see  reduced  figures  of  Proto- 
spongia  on  Plate  XXVI. 

f  See  Columnaria,  on  Plate  XXVI.  Note.  The  figure  of  Monticulipora 
(  Favosites)  ly  coper  don  should  be  removed  from  this  plate  to  Plate  XXXII, 
as  it  is  a  well  recognized  Trenton  fossil,  growing  in  colonies  on  the  Dela- 
ware and  Bushkill  in  Northampton  county,  and  elsewhere.  See'  Fossil 
Dictionary  of  Pa.  p.  421. 

J  See  Plate  XXVIII.  Note.  The  Murchisonia  milleri  on  plate  XXVII 
ought  to  be  removed  to  plate  XXXVI,  for  it  is  of  Trenton  age.  The  Chazy 
Euomphalus  catilloides  on  plate  XXX  was  a  large  shell,  and  its  cross  sec- 
tion lines  in  calcite  make  spirals  on  the  Great  Valley  limestones. 


502  GEOLOGICAL    SURVEY    OF   PENNSYLVANIA. 


XXV/ 


jfossils  tf  formation  II  &.  ?! 


onocraterion.  lesleyi.     Prime. 


THE   FOSSILS   OF  NO.   II.  503 

floating  shells  like  Orthoceras  primigenium  (plate  XXIX) 
had  already  existed  long  enough  to  develop  several  species 
in  the  Calciferous,  more  in  the  Chazy,  and  fairly  took  pos- 
session of  the  Trenton  open  sea.*  Pteropod  (wing-footed) 
shells  of  several  species  existed  in  the  Calciferous  sea  in 
colonies,  f  The  Trilobites  began  in  the  Cambrian  (or  per- 
haps Pre- Cambrian  age)  and  must  have  been  abundant  in 
the  whole  Lower  Silurian  age.:}:  No  higher  forms  of  life 
are  known,  neither  crustaceans  nor  fishes;  but  it  is  probable 
that  they  existed  and  their  remains  will  some  day  be  found, 
seeing  that  large  plates  of  armored  fishes  like  the  Devon- 
ian Holoptychius  (in  No.  VIII)  were  discovered  three  years 
ago  with  Trenton  species  of  shells  in  Colorado. 

It  has  always  been  considered  a  surprising  fact  that  the 
keen-sighted  and  zealous  naturalists  of  Philadelphia  and 
West  Chester  have  never  been  able  to  collect  fossils  from 
the  Chester  Valley  limestones  ;  nor  those  of  Lancaster  and 
York  from  the  innumerable  limestone  outcrops  east  and 
west  of  the  Susquehanna  river;  although  the  Calciferous, 
Chazy  and  Trenton  age  of  the  rocks  was  never  seriously 
called  in  question,  and  their  connection  with  the  rocks  of 
the  Great  Valley  was  evident.  Nor  in  the  Great  Valley 
itself  has  any  notable  collections  been  made  by  the  college 
students  of  Easton,  Bethlehem,  Allentown,  Carlisle  and 
Chambersburg.  Either  the  Calciferous  and  Chazy  forma- 
tions were  laid  down  on  a  very  deep  sea  bottom  far  from 
the  shores  which  we  know  abounded  in  a  great  variety  of  life, 
or  the  remains  of  plants  and  animals  were  afterwards  ob- 
literated by  pressure^  dissolution  and  partial  crystalliza- 
tion, which  hardly  seems  probable  in  view  of  the  fact  that 
the  Trenton  rocks  in  Northampton  county  are  tolerably 

*  See  their  chambered  structure  on  plate  XXXVII,  and  a  specimen  of  the 
coiled  Lituites  on  that  plate ;  also  a  curved  Cyrtoceras  of  Cha/y  on  plate 
XXXI. 

t  See  Primitiagregaria  on  plate  XXIX.  But  they  have  not  been  collected 
at  Pennsylvanian  localities.  They  became  enormously  abundant  in  the 
Clinton  age  (  Va)  as  may  be  seen  by  an  inspection  of  any  piece  of  fossil  iron 
ore  from  Danville,  Bloomsburg,  Orbisonia  or  Frankstown. 

t  See  Asaphus  canalis,  on  plate  XXIX,  and  other  genera  on  plates  XXXI, 
XXXVIII,  XXXXIII. 


504 


GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 


a^nes/an  limestone) 


Jfolla. 

Leptasna  sericea.     (Strophomena  sericea,} 


Tryblidium  ovale,  Whitfield,  Bull.  Amer.  Mus.  Nat.  Hist 


Orthis  tritonia,  Bill.  Tryblidium  P  aoutum,  Tryblidium  pileolu 


Rhynchonella  plicifera., 

Rhynchonella  altilis.  '  (Atrypa 


Murchisonm  linearis,  B  Murchisonia  milleri 

^  I'ennsy 
}  ton  & 
,:-Y.  Vol. 
ilUCaj . 


THE   FOSSILS   OF   NO.  II.  505 

fossiliferous,  and  Trenton  fossils  have  been  collected  at 
Chambersburg,  and  also  in  the  narrow  up-faulted  limestone 
belt  east  of  Doylestown  in  Bucks  county.* 

Recently,  however,  an  enthusiastic  mineralogist,  a  post 
graduate  of  Haverford  College  in  Delaware  county,  Mr.  M. 
B.  Stubbs,  while  hunting  for  quartz  crystals  near  Hender- 
son's station  on  the  Chester  Valley  railroad,  found  a  con- 
siderable number  of  silicified  internal  casts  of  three  species 
of  gasteropod  shells  and  one  cephalopod  (Orthoceras)  in 
loose  fragments  of  sandstone  lying  on  the  upturned  lowest 
limestone  beds  of  the  valley  and  therefore  presumably  from 
the  slope  of  the  North  Valley  hill  of  Chiques  quartzite. 
The  casts  (now  in  the  museum  of  the  Acad.  Nat.  Sciences, 
of  Philadelphia)  are  distorted  and  flattened  by  pressure, 
and  their  Calciferous  age  cannot  be  certified  by  any  specific 
characteristics,  but  few  who  saw  the  specimens  would 
doubt  it. 

Scolithus  linearis  has  been  reported  plentiful,  with  water- 
worn  pebbles,  in  a  sand  pit  on  the  road  from  Barren  Hill  to 
Chestnut  Hill,  by  Dr.  G.  M.  Stiles  of  Conshohocken,  at 
a  meeting  of  the  A.  N.  S.  Philadelphia,  May  20, 1891.  These 
are  the  first  discovered  in  the  neighborhood.  It  is  natural 
to  suppose  that  they  came  from  the  North  Valley  Hill  or 
Chiques  quartzite,  and  Prof.  Heilprin  suggested  that  the 
sand  pit  is  on  the  line  of  an  abandoned  channel  of  the 
Schuylkill  river.  But  it  is  also  possible  that  the  fossils  be- 
long to  some  sandstone  layer  in  the  Calciferous  sandstone 
or  even  Chazy  division  of  II  seeing  that  Scolithus  is  so 
numerous  at  that  horizon  in  Vermont.  Search  for  Scolithus 
in  the  sandy  limestone  series  itself  ought  to  be  made. 

It  is  hard  to  believe  that  we  are  never  to  know  more  of 
the  animal  life  of  the  Calciferous  and  Chazy  waters  than 
from  ihe  specimen  of  Maclurea  magna  (?;  and  one  or  two 
others  mentioned  in  the  reports  of  Lehigh  and  Northamp- 
ton counties  by  Prof.  Prime.  It  surely  only  needs  a  sys- 

*Here  Dr.  Isaac  Lea  obtained  a  few  shells  from  the  building  stones  of  a 
limekiln  many  years  ago.  It  is  not  known  if  the  Trenton  has  been  pre- 
served along  the  Chester  county  valley,  or  whether  its  beds  have  been  con- 
verted into  Avhite  marble. 


506  GEOLOGICAL   SURVEY    OF   PENNSYLVANIA. 


XXA///I 


CLlldstdne  (Mayncsian  limestone^  \ 


THE   FOSSILS   OF   NO.  II.  507 

tematic  search  for  them  with  the  trained  eyes  of  an  expert 
palaeontologist,  or  even  with  the  untrained  eyes  of  any  col- 
lege student  whose  zeal  for  natural  history  equals  the  sharp- 
ness of  his  youthful  vision.* 

There  is  one  kind  of  fossil  forms  for  which  special  search 
should  be  made,  the  so  called  Conodonts ,  or  minute  teeth, 
most  probably  of  leeches.  Worms  were  abundant  in  the 
shallower  parts  of  the  sea,  as  is  shown  by  tracks  and  bur- 
rows, although  the  figures  of  PalceopJiycus  on  plates  XXVI 
and  XXXI,  and  Phytopsis  on  plate  XXXII  are  almost  un- 
doubted impressions  of  algge  or  seaweeds. 

Conodonts  were  first  found  by  Pander  in  the  lowest  Silu- 
sian  rocks  of  Russia,  f  Mr.  Hinde  found  them  in  the  dark 

*The  Calciferous  Sandstone  Valley  of  Copake,  Millerton  and  Arnenia,  in 
Eastern  New  York,  an  extension  beyond  the  Hudson  of  the  Great  Valley  of 
Pennsylvania,  containing  the  largest  bodies  of  limonite  in  the  Taconic 
region,  have  yielded  numerous  specimens  of  Ophileta,  Orthoceras,  Cyrto- 
ceras,  &c.,  to  the  keen  search  of  Mr.  W.  B.  Dwight,  in  1889.  (See  Am.  Jour- 
Sci.  Vol.  38,  page  150  ;  Vol.  39,  p.  68. )  He  found  also  in  the  limestone  near 
Clove  Valley  Station,  Dutchess  county,  N.  Y.  Calciferous  fossils,  including 
the  common  fucoids,  with  Ophileta,  probably  O.  complanata ;  proving  that 
the  Fishkill  belt  east  of  the  Hudson  is  merely  a  continuation  of  the  Great 
Valley  limestone  belt  of  Pennsylvania  and  New  Jersey.  (Aua.  Jour.  Sci. 
Vol.  39,  Jan.  1890,  pp.  68,  71.)  Also  in  the  so  called  "Taconic"  limestone 
belt  of  Columbia  county,  N.  Y.  near  Pulver's  Station,  2£  m.  north  of  Phil- 
mont,  Mr.  L.  P.  Bishop,  in  1887,  found  gasteropods,  crinoids,  and  a  brachio- 
pod  shell ;  and  in  1888,  six  or  seven  Orthocerata,  <&c.,  Cheteles  compacta, 
Billings ;  Monticulipora  lycoperdon,  Say  ;  Orthis  testudinaria  (?)  Dal. ; 
and  Murchisonia  gracilis,  in  hard  limestone,  a  mile  long,  150  yards  wide, 
completely  enclosed  in  highly  metamorphosed  schists  and  slates.  (Am. 
Jour.  Sc.  Vol.  39,  page  70.  The  Chatham  find  of  a  like  nature  is  recorded 
in  Vol.  32,  pp.438,  1886.) 

fMonog.  Foss.  Fische  d.  Sil.  Syst.  1856.  Pander  called  them  fish  teeth. 
Harley  found  them  in  the  Ludlow  bone  bed  and  referred  them  to  crusta- 
ceans. Q.  J.  G.  S.  London,  1861,  p.  542.  C.  Moore  found  them  at  various 
horizons  from  Silurian  up  to  Permian.  Report  of  Brit.  Ass.  1869,  p.  375; 
and  private  note  in  Hinde's  "On  Conodonts,"  &c.  Q.  J.  G.  S.  1879,  p.  351  to 
359,  with  three  plates  full  of  figures.  C.  J.  Smith  in  1875  found  them  in 
Scotch  Low.  Garb,  rocks.  Notes  by  Young,  N.  Hist.  Soc.,  Glasgow.  Dr. 
Newberry  found  them  in  Low  Carb.  rocks  of  Bedford,  Ohio  ;  and  figured 
them  as  the  teeth  of  Mixinoid  fishes  in  Pal.  Ohio,  Vol.  II.  In  the  Hudson 
River  formation  (No.  Ill)  near  Toronto  a  few  compound  cone-teeth,  mixed 
with  a  great  variety  of  grapholites,  corals,  worms  and  brachiopod,  gastero- 
pod  and  cephalopod  shells,  and  a  few  fragments  ot  a  trilobite  (Calymene), 
are  found  in  thin  limestone  lenses  between  micaceous  flags  and  shales ; 
there  are  also  some  simple  spine-like  cone-teeth,  a  form  not  yet  seen  except 


508  GEOLOGICAL   SURVEY   OF    PENNSYLVANIA. 


XX  JX 


an  limestone) 


Orthoceras  becki,  Billings. 

•C-ttl. Canada.    3Ji. 


Orthoceras  deparcum,  Primitia  gregaria,  WhitfieM. 


(ol  7mit;aBe eiyi\    '-n 

^ "l°/r— -i.    •     7?B»51  "V55 


Orthoceras  montrealense,  Billings.    Geol.  Canada,  1863 


Orthoceras  primigenium,  Van 


M.IIT).  fifiazy  or  MdclleSreat  Yall.ey  limestone. 

SUccopora 

fe 


Husophycus  bllobatus  ( 


Orthis  acuminata, 
I  V  «      ° 

J?       Orthis  imperator,  Billings.    Can.  Nat.  A  Geol.  Vol 


THE   FOSSILS   OF   NO.  II.  509 

Chazy  limestone  beds  at  Greenville  on  the  Ottawa  river  in 
Canada,  beds  which  are  largely  made  up  of  the  small  shells 
of  bivalve  crustaceans  (Leperditia)  with  a  few  small  trilo- 
bites  and  gasteropods,  for  all  of  which  the  cone-teeth  would 
be  much  too  large,  since  they  all  belong  to  the  largest 
known  compound  cone-tooth  species. 

The  cone-teeth  are  very  minute  shining  bodies,  single 
curved  conical  teeth  with  expanded  base,  or  more  fre- 
quently a  row  of  small  cones  with  a  larger  one  at  the  end 
or  in  the  middle  of  the  row,  sometimes  with  a  downward 
extended  base  carrying  itself  denticles,  f  They  retain  their 
perfect  form  and  lustre,  whether  in  flag,  shale  or  limestone 
beds,  although  very  brittle  and  easily  dissolved  by  nitric 
acid.  Most  of  them  are  of  reddish  horn  color  and  translu- 
lucent ;  rarely  of  a  milky  white,  and  only  where  weathered. 
Those  at  North  Evans  are  robust  and  opaque,  with  a  differ- 
ent lustre  from  those  in  the  bituminous  shales.  Those 
from  the  CJiazy  differ  from  all  the  rest  in  the  bright  glossy 
black  tint.  Microscopic  sections  show  a  conical  lamellar 
structure.  Usually  found  scattered  through  the  rock. 
Hinde  has  one  Genesee  specimen  in  which  a  compressed 
group  of  various  forms  of  teeth  and  plates  have  evidently 
belonged  to  one  animal,  but  too  much  crushed  to  make  out 

in  the  Lower  (Cambro)  Silurian.  While  most  of  the  other  fossils  are  in  the 
limestone  beds  the  cone-teeth  are  generally  found  in  the  shales. 

In  Upper  Hamilton  lime-shales  (YIIIc)  finely  exposed  at  North  Evans, 
on  the  Lake  Erie  shore  in  New  York  State,  cone-teeth  are  numerous,  and 
one  particular  limestone  bed  is  so  filled  with  their  fragments  as  to  be  called 
by  Hinde  the  Conodont  bed;  |"  to  3"  thick;  traceable  for  some  distance; 
dark,  sub-crystalline,  with  green  particles,  and  pyrite  crystals ;  holding 
also  crinoid  stem  fragments,  fish  bones  and  plates,  Ptycodus  teeth  of  Pan- 
der, but  neither  crustaceans  nor  gasteropods.  The  cone-teeth  can  only  be 
detected  with  a  good  lens,  and  on  weathered' surfaces.  A.  few  cone-teeth  as- 
sociated with  fish  plates  and  teeth  have  been  found  in  a  thin  Hamilton  lime 
bed  at  Arkona,  Lambton  county,  Ontario. 

In  black  Genessee  shale  cone-teeth  have  been  found  by  Hinde  at  Kettle 
creek  and  Bear  creek,  Canada  West ;  in  fragments  on  the  north  shore  of 
Lake  Erie ;  in  the  fine  section  at  North  Evans,  N.  Y.  ;  and  at  Louisville, 
Ky.  ;  mixed  with  a  small  number  of  Lycopod  plant  spores,  broken  plants, 
a  few  Lingulas,  Discinas  and  Aviculas,  and  Palceoniscus  fish  scales  ;  but  no 
forms  to  which  the  cone-teeth  could  easily  belong. 

The  Lower  Carboniferous  black  shales  in  which  Newberry's  conodonts 
occur  show  nothing  else  than  plants  and  ganoid  fish  scales. 

fFor  other  forms  see  Hinde's  description  on  p.  354  and  his  plate  figures. 


510  GEOLOGICAL    SURVEY   OF   PENNSYLVANIA. 


Mill.  CAazy  orlMiddle  9reat  Yalley  limestone. 


Orthepwnoides       Orthis  pervetus.  Conrad 


R.554.       ^5^     Hall. 1.6.5. 

Kaphistoma   striatuu 

.-"-^•>r"-  Rapliistom* 

planrstria. 


FOSSILS   OF   THE   CALCIFEROUS,  lid.  511 

their  arrangement.  Huxley  saw  a  resemblance  to  the  hag 
fish  (Myxine),  but  could  indicate  no  living  fish  with  a  simi- 
lar assemblage  of  teeth  and  plates.  Owen  at  first  suggested 
that  they  might  possibly  be  toothed  crustaceous  claws  ;  af- 
terwards, that  they  might  rather  be  spines,  booklets,  den- 
ticles of  naked  shell-fish  or  worms.  They  seem  to  have 
been  the  only  preservable  part  of  the  animal  whatever  it 
was ;  and  they  may  possibly  be  the  only  evidence  we  have 
for  the  early  existence  of  the  soft  circle-mouthed  family  of 
fishes.  Dr.  Woodward  suggested  that  they  might  be  the 
tongue-armor  of  the  shell-less  gasteropods  (Nudibran- 
chiata)  which  have  therefore  never  been  found  in  the  rocks.* 

Fossils  of  tJie  Calciferous,  Ila. 

Some  of  the  most  characteristic  and  most  widely  dis- 
tributed forms  of  this  formation,  are,  according  to  S.  A. 
Miller's  N.  A.  Geology  and  Palaeontology, f  Ophileta  com- 
planata,  Ophileta  U7iiangularis,  Holopea  turgida^  Hol- 
opea  dilicula,  and  Pleurotomaria  primigenium. 

From  the  Potsdam  ascend  into  this  Calciferous  division, 
Pleurotomaria  canadensis  and  Leptcena  barabuensis. 

The  following  have  been  assigned  to  this  formation  (or 
to  supposed  equivalents  of  it  in  the  Quebec  group)  Pluro- 
tomaria  calcifera,  Pleurotomaria  postumia,  Helicotoma 
perstriata,  Maclurea  matutina,  Maclurea  sordida,  Eccy- 
liomphalus  canadensis,  Camarella  calcifera,  Lingulella 
mantelll,  Lingulella  iren.e,  Amphion  salteri,  Bathyurus 
cordai,  Bathyurus  conicus,  and  Asaphus  canalis;  but  the 
identifications  of  Quebec  and  Calciferous  strata  are  always 
to  be  distrusted. 

Fossils  of  tlte  Quebec  group. 

Of  these  the  less  said  the  better  until  the  controversy  over 
the  Quebec  group  has  been  settled.  The  species  Lingulepis 
maera,  mlnuta,  andmanticula,  Acroteta  gemma,  Agnostus 
communis,  bidens,  and  neon,  Crepiceplialus  Tiaguei,  and 

*Q.  J.  G.  S.  XXXV,  p.  389. 

t  Second  Edition,  Cincinnati,  1889,  page  34. 


512  GEOLOGICAL   SURVEY    OF  PENNSYLVANIA. 


XXXf 


Orthocerata  figured  by  Em  i  Orthoceras  multillneatum.  Calymene 


FOSSILS   OF  THE   CHAZY,    II  b.  513 

unisulcatus  are  confidently  assigned  to  equivalents  of  the 
Quebec  group  in  the  Rocky  Mountains.  The  family  of 
Graptolites  is  said  to  reach  its  highest  development  in  the 
Quebec  group.  Thirty  genera  and  170  species  of  Grapto- 
lites  have  been  named  thus  far  in  North  American  rocks. 
Maclurea  atlantica  and  Asaphus  canalis  are  said  to  range 
up  through  the  Chazy  and  higher.* 

Fossils  of  the  Chazy,  11  b. 

The  characteristic  form  of  this  age  is  considered  to  be 
the  line  whorl-shell  Maclurea  magna.  With  this  are  as- 
sociated others  which  continued  to  live  even  into  Hudson 
River  times : — Stropliomena  alternata,  and  incrassata, 
Orthis  perveta,  Leperditia  canadensis,  loucTcana,  and 
amygdalina,  Orthoceras  multicameratum,  and  Mlineatum 
and  the  lamellibranch  shell  Modiolopsis  nasuta.  Scolithus 
is  abundant  in  the  formation  as  recognized  in  some  regions; 
and  Lingulepis  morsel  is  described  from  the  St.  Peter's 
sandstone  of  the  west.f 

Fossils  of  the  Blac'K  River  limestone,  II  c  (in  part). 

These  were  defined  by  Vanuxem  in  1842  in  the  bluffs  of 
Birdseye  and  Trenton  beds  at  Boonville,  N.  Y.,  but  there 
has  always  been  a  doubt  of  the  propriety  of  separating  the 
Black  river  and  Birdseye  beds  and  giving  two  names  to  what 
seems  like  one  formation,  distinguished  on  the  Black  river 
by  its  abundance  of  Cephalopod  shells,  and  on  the  Mohawk 
river  by  an  abundance  of  the  Birdseye  fucoid  Phylopsis 
tubulosa. 

The  vast  and  varied  population  of  the  sea  at  the  begin- 
ning of  the  Trenton  age,  as  shown  in  the  Black  river  beds, 
produced  by  its  decay  the  dark  color  of  the  rocks,  the 
black  marbles  of  Vermont  and  Pennsylvania.  Many  of 
the  species  died  out  however  before  the  normal  Trenton 
limestones  were  deposited.  But  the  family  of  straight 

*  This  paragraph  is  a  condensation  ot  statements  made  by  S.  A.  Miller  on 
his  page  35. 
t  S.  A.  Miller,  1889,  p.  38. 

33 


514  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 


Phytopsia    tubulosa  P     (Fucoidet  demittu*.)    V 


3$ircLei/&  and  ^Blaclc^&ivw*: 
</ 


Tetradinmfibratum.Bafford.  American  Journal  of  Sci«l 


FOSSILS    OF   THE   BLACK   RIVER   LIMESTONE,  II  C.        515 

shell  cephalopods  (OrtJioceras]  reached  its  climax  now,  not 
only  as  to  the  number  of  its  species,  but  as  to  the  size  of 
its  individuals,  some  of  them  having  had  tapering  cham- 
bered shells  ten  feet  long  and  twelve  inches  in  diameter  at 
the  head.  The  allied  Cyrtoceras  and  Endoceras  were 
highly  developed ;  and  the  genera  Oomphoceras,  Phrag- 
moceras  and  Gyroceras  brought  their  species  into  the  field.* 
Corals  also  were  abundant  in  places,  and  petroleum 
exudes  from  their  fossil  forms  when  broken,  as  at  Mont- 
morency  in  Canada,  f 

Fossils  of  the  Birdseye  limestone,  lie  (in  part). 

The  charactersstic  fossil  of  the  Birdseye  limestone  is  a 
vertical,  cylindrical,  sub-cylindrical,  angular  or  compressed 
stem  of  a  marine  plant,  branched,  connected,  forking,  radiat- 
ing, looped,  etc.  etc.  with  an  internal  fibrous  structure,  as 
shown  in  Hall's  figures  of  1843,  Vol.  1,  Pal.  N.  Y.  plates 
8  and  9,  which  seem  to  exclude  the  possibility  of  these 
markings  being  casts  of  worm  burrows,  as  insisted  on  by 
Salter  and  Etheridge,  and  so  tabulated  by  Bigsby  in  his 
Thesaurus  Siluricus.:}: 

*  Where  were  the  feeding  grounds  of  these  hugh  floating  walking-canes  of 
stone,  ballasted  below  and  buoyed  by  their  air-filled  chambers  above,  with 
their  great  eyes  looking  for  prey,  and  their  long  arms  spread  out  at  the  sur- 
face of  the  water  to  seize  and  bring  it  to  their  mouths?  Requiring  but 
little  depth  of  water  they  probably  haunted  the  shores  of  the  then  conti- 
nents and  Avere  supplied  with  abundant  provender  by  the  scum  of  trilobites 
which  floated  like  themselves  as  water  bugs  upon  the  waves.  The  brachio- 
pod  and  lamellibranch  shells  were  no  doubt  safe  from  their  attacks ;  yet  the 
shore  waters  must  have  been  their  most  profitable  haunts ;  and  if  so  we  can 
comprehend  the  vast  abundance  of  their  remains  in  Northern  New  York 
and  their  comparative  absence  from  the  rocks  of  Pennsylvania.  Or,  were 
they  endowed  with  sails  like  the  modern  nautilus,  and  made  voyages  before 
the  wind  ?  It  is  a  pity  that  the  rocks  have  preserved  for  us  no  lithographs 
of  their  curiously  unknown  soft  heads  and  bodies. 

fThe  same  thing  happens  when  the  corals  of  the  Niagara  rocks  of  New 
York  are  broken  out.  Such  facts  establish  the  animal  origin  of  the  older 
and  more  fetid  petroleums  ;  the  later  and  sweeter  oils  having  come  from  the 
chemical  change  of  the  cellular  tissue  of  marine  vegetation,  as  shown  by 
Lesquereux. 

J  See  what  is  said  in  Chap.  XVII  on  Scolithus,  beginning  page  287  above. 
See  also  reduced  figures  of  the  Phylopsis  tubulosa  given  at  the  top  of  plate 
XXXII.  Hall's  figures  will  be  reproduced  in  the  Appendix  to  Fossil  Dic- 
tionary. 


516  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 


xxxm 


and  attack  jtive 


MJTc.  ^frmton,    i 


(IW.,  P»l.   N.   V        Conularia  gracilis        Conularia    papillata.  Atrypa  exiRua 


Orthis  aequivalviB.     Hall  Orthis  bellara?osa.     Conrad,  Orthis  lynx,  ( Deltfiytif  lynx  ;  ft 


JjB^MI  fl  ft  ^^^  ^^^     ^f, 


OrthiBpectinella,  Conrad.  Ann.Rt.  N.  Y.1840.  Bl 


Orthifl  subquadrata,  Hall.  Pal.  N.  Y.  Vol.  1.  1847.    Tren-  II  c,          »    <^°f.C 

•*  «         5-r-«.     * 


FOSSILS   OF   THE  TRENTON   LIMESTONE,  II C.  517 


fossils  of  the  Trenton  limestone  II  c. 

This  famous  formation  was  first  described  by  Emmons  in 
1842.  At  Trenton  Falls  in  New  York  it  shows  100  feet  of 
very  fossiliferous,  dark,  fine-grained,  thin-bedded  limestone 
layers  below,  separated  by  black  shales,  passing  up  into 
coarse  grey,  thick,  less  fossiliferous  beds  at  the  top.  At 
Cliazy  it  is  400'  thick.  In  middle  Pennsylvania  it  is  1000' 
and  1200'  thick.  In  middle  Tennessee  only  500',  it  is  in 
eastern  Tennessee  1100'  thick.  In  Canada  it  is  600'  thick  at 
Montreal,  750'  further  west,  but  only  50'  around  lake  Mich- 
igan. In  Iowa  and  Illinois  its  lower  blue  division,  120'  thick, 
is  capped  by  the  lead  and  zinc-bearing  dolomitic  layers  of 
Galena,  150'  thick.  In  Missouri  it  is  400'. 

Its  wide  distribution  attests  an  open  and  moderately  deep 
sea  deposit.  Its  wealth  of  life  is  exceptionally  great. 
Graptolites  and  Trilobites  were  on  the  decline;  but  Crinoids, 
Cystideans,  Brachiopods,  Corals,  Gasteropods  and  Lamelli- 
branchs  were  on  the  increase.* 

*  C.  A.  Miller's  Geol.  and  Pal.  N.  Amer.  1889,  p.  41.  I  cannot  do  better 
than  extract  the  interesting  paragraphs  from  this  indespensable  guide  to  the 
student  of  fossils  which  follow  on  pages  41,  42  : 

"  Receptaculites  oweni  is  peculiar  to  and  characteristic  of  the  Galena  di- 
vision of  this  Group,  and  it  is  usually  accompanied  with  Lingula  quadrata, 
Murchisonia  major,  -Fusispira  elongata,  and  other  characteristic  species. 
The  species  most  characteristic  of  the  Trenton  Group,  and  which  may  be 
relied  upon  as  determining  its  age  wherever  they  occur,  are  Orthis  tricen- 
aria,  found  in  New  York,  Canada,  Kentucky,  Missouri,  and  Nevada;  Ort/ti 
pectinella,  found  in  New  York,  Canada  and  Kentucky;  Cyrtolites  comprca- 
sus,  iound  in  New  York,  Canada,  Wisconsin  and  Minnesota;  Hybocriinis 
tumid  us,  H.  conicus,  Amygdalocystites  florealis,  A.  radiatus,  Blastoidos 
crinus  carcharidens,  found  at  Ottawa,  Canada,  and  High  Bridge,  Kentucky; 
Leper ditiafabulites  and  Conularia  quadrata,  found  in  New  York,  Canada 
and  Kentucky;  and  Orthis  borealis,  found  in  Canada,  Wisconsin,  Minne- 
sota and  Kentucky.  The  genus  Amygdalocystites  has  a  wide  geographical 
distribution,  though  a  rare  fossil  in  every  locality,  and,  so  far  as  known,  is 
confined  to  this  Group.  Other  characteristic  species  are  Bythotrephis  suc- 
culens,  Monticulipora  lycoperdon,  Schizocrinus  nodosus,  Stictopora  ele- 
gantula,  Orthis  bellarugosa,  O.  cequivalvis,  Trochonema  umbilicatum, 
Subulites  elongatus,  and  Helicotoma,  planulata. 

"  There  are  numerous  species  which  continued  to  live  until  the  Hudson 
River  age,  and  are,  therefore,  common  to  three  Groups,  as  Strophomena  al 
ternata,  8.  rhomboidalis,  Leptena  sericea,  Zygospira  modesta,  Rynchonella 
capax,  Calymene  callicephala,  Asaphus  gigas,  and  Ceraurus  pleurezanthe- 


518 


GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 


~ -*         Vol.1,  PI.  Vlt. 

Strophomena  (Leptcena)  alternistrlata,  Hall,    Pal.  N.  Y 


FOSSILS   OF   THE  TRENTON   LIMESTONE,  II  C.  519 

The  Trenton  fossils  have  been  in  Pennsylvania  best 
studied  at  Bellefonte  in  Centre  county.  Strata  occur 
'''•composed  almost  entirely  of  fossil  remains,"  all  of 
them  recognized  Trenton  forms.  Prof.  Ewing,  late  of  the 
State  College  in  Centre  county,  adds  in  his  report  (embodied 

mus.  Sucli  species  are  usually  quite  variable  in  form  and  size,  and  seem  to 
have  changed  to  su^t  the  conditions  of  their  habitat,  and  also,  in  accordance 
with  the  theory  of  evolution,  to  have  reached  the  climax  of  development, 
and  subsequently  gradually  declined.  Strophomena  rhomboidalis  occurs 
in  Trenton,  Utica  Slate,  Hudson  River,  Clinton,  Niagara,  Lower  Helderberg, 
Upper  Helderberg,  Hamilton,  Chemung,  Waverly,  Burlington  and  Keokuk 
groups.  Its  vertical  range  exceeds  that  of  any  other  species  in  any  of  the 
rocks  of  the  known  world,  and  its  geographical  distribution  is  common  to 
every  continent  where  strata  of  these  ages  have  been  studied  and  described. 
The  varietal  forms  have  been  called  S.  tenuistriata  from  the  Lower  Silurian, 
S.  depressa  from  the  Upper  Silurian,  and  S.  rhomboidalis  from  the  Devon- 
ian and  Subcarboniferous.  The  Lower  Silurian  specimens  are  usually 
smaller,  and  have  fewer  concentric  wrinkles  over  the  visceral  region  than 
those  from  the  Upper  Silurian  and  Devonian,  while  the  length  of  the  front 
and  lateral  margins  from  the  geniculation  is  usually  greater  in  the  Upper 
Silurian  than.it  is  in  the  Lower  Silurian,  Devonian  or  Subcarboniferous 
specimens  ;  but  these  differences  are  not  so  constant  as  to  form  inflexible 
characters,  and  hence  it  is  that  many  of  the  learned  and  better  palaeonto- 
logists have  classed  them  all  together  under  the  first  and  oldest  specific 
name.  The  various  forms  which  Strophomena  alternata  assume  in  the  same 
group  of  rocks  are  wonderful;  the  radiating  striae  differ  in  size  and  number, 
the  hinge  line  is  sometimes  longer  and  at  other  times  shorter  than  the  great- 
est width  of  the  shell.  The  shells  are  sometimes  much  longer  than  wide, 
and  at  other  times  as  much  shorter.  The  lateral  sides  are  sometimes  straight, 
and  at  other  times  rounded.  Some  shells  are  nearly  flat,  others  are  deeply 
concave  on  the  dorsal  side  and  highly  convex  on  the  ventral.  Age  in  some 
specimens  appears  to  have  materially  thickened  the  shells,  and  preserved 
strong  imbricating  lines  of  growth,  while  in  other  cases  we  have  much  larger 
shells  that  are  very  thin  and  destitute  of  imbrications.  Like  differences  may 
be  distinguished  in  other  species  having  great  vertical  distribution,  as  in 
Rhynchonella  capax  and  Zygospira  modesta. 

"  The  rocks  of  this  Group  are  composed  almost  entirely  of  remains  of  the 
hard  parts  of  animals  that  swarmed  in  the  seas  of  that  age.  Some  shells  are 
preserved  in  good  condition,  but  generally  the  comminuted  fragments  are 
held  together  by  lime  cement,  forming  the  limestone  strata,  leaving  well- 
preserved  specimens  to  be  found  only  in  the  shaly  partings.  It  is  common 
to  flnd  that  one  animal  has  grown  upon  another,  as  a  Lichenocrinus  upon  a 
brachiopod,  and  a  bryozoan  upon  the  former,  under  such  circumstances  as 
to  show  the  shell  was  at  the  bottom  of  the  ocean  during  the  growth  of  the 
Lichenocrinus,  and  that  the  latter  must  have  ceased  to  grow  before  the  bry- 
ozoan attached.  From  this  we  infer  the  clearness  of  the  water,  for  otherwise 
mud  would  have  intervened;  and  we  also  infer  a  slow  deposition  of  materials ; 
for  the  lives  of  two  animals  transpired  before  the  deposit  was  sufficient  to 
cover  a  thin  shell.  There  is  no  evidence  of  any  difference  between  the  tem- 
perature of  the  water  then  and  now,  nor  between  the  climate  then  and  now. 


520  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 


X.XVV 


M.  lie. 


Modiolop.1.  trentonensi.,  Hall,        Modiolopsis  meyeri,  Bill;     Modiolopnis  .  maia,          Modiolopais  carinata, 


FOSSILS    OF  THE  TRENTON   LIMESTONE,  II  C.  521 

in  Report  T4,  p.  424)  the  following  list: — Schizocrinus 
nodosus  (stems  of  this  stone  lily);  Streptelasma  cornicu- 
lum  ;  OrtMs  testudinaria  (very  common  above);  OrtMs 
tricenaria;  OrtMs  pectinalinea ? ;  OrtMs  lynx;  Ortlus 
subequalis  ;  Strophomena  alternate,  (very  common  above); 
Leptcena  sericea  (common  above);  Lingula  curia  (one); 
Pleurotomaria  lenticular  is,  arid  another  species ;  Mur- 

cTiisonia  gracilis  ;  Leperditia ?;  Trinucleus  concentri- 

cus  ;  Calymene ?;  Clienteles  ly  coper  don. 

Mr.  C.  E.  Hall  in  his  collection  lists  published  in  the 
Catalogue  of  the  Museum  of  the  Survey,  O3,  1889,  page 
177  et  seq.,  adds  to  the  above,  numerous  Bryozoa  ;  Sticlopora 
acuta  /  fragments  of  Tentaculites  ;  Ceramopora f;  frag- 
ments of  Trematopora ;  Monticulipora  pulchella ;  Bey- 
ricMa  (numerous);  Zygospir a  modes ta  ;  CalymenebecTcii  ; 
an  Orthoceras  (encrusted  with  bryozoans);  SpirorMs  (num- 
erous); a  Better ophon.  Again  on  p.  183,  Edmondia  sub- 
truncata;  Murchisonia  gracilis;  Cypricardites  sub- 
truncatus  ;  Camarella  ambigua  ;  Camarella  liemiplicata  ; 
Palceophycus  simplex  (in  fair  condition);  Buthotrephis 
succulens  ;  Asaphus  obtusus  ;  a  colony  of  Lept(Eiia  sericea 
on  one  slab;  an  lllcenus ;  Cypricardites  ventricosus ; 
Plumulites  jamesii ;  Pholidops  trentonensis ;  Geraurus 
pleurexantJiemus  ;  Atrypa  altilis. 

In  Fellows'  collections  for  C.  E.  Hall  in  Trenton  layers 
on  the  Little  Juniata  at  Tyrone  Forge  (List  in  O3,  p.  189), 
appear,  with  many  of  the  above,  these  also  :  Rliynchoii- 
ella  cap  ax ;  EscTiaropora  (Philodictya)  recta  ;  Retepora  ; 
Cornulites  Jlexuosus  ;  and  Stictopora  elegantula. 

Reedsville,  in  Mifflin  county,  is  another  excellent  collect- 
ing ground  for  Trenton  fossils,  where  many  specimens  of 
Homalonotus  trentonensis  were  got.  (See  list  in  O3,  p. 
179.)  Among  other  forms  are  noticed  OrtJiis  costatus  ;  En- 
doceras  proteiforme ;  Lingula  oblong  a  ;  Bathyurus  ex- 
tans  ;  Modiolopsis  faba  ;  and  RapTiistoma  lenticular  is. 
The  two  last  were  collected  also  near  Martinsburg  in  Mor- 
rison's Cove  in  Blair  county.  (O3,  p.  181.) 

Collections  were  also  made  at  Belleville,  in  Mifflin  county, 


522  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 


Holopea  veutrioosa.    (Hall,  Pal.  N.  Y.V.        Holopea paludlniformis.    (Hal!       Macrocheilus  subcostatus  P  Ow 


FOSSILS   OF   THE  TRENTON   LIMESTONE,  II  C.  523 

by  Mr.  Billin,  at  Campbell's  quarry  in  Trenton  limestone 
top  beds.  (O3,  190.) 

I  have  found  colonies  of  Trenton  brachiopod  shells  cov- 
ering slabs  of  limestone  in  the  Nippenose  and  Oval  Mus- 
quito  valleys  of  Lycoming  county. 

The  Trenton  belt  in  Northampton  county  is  rich  in  cri- 
noidal  stems,  with  OrtJiis  pectinella,  and  Atrypa  recticu- 
laris  at  Martin's  creek  on  the  Delaware,  and  in  the  numer- 
ous quarries  along  the  line  crossing  the  Bushkill.  See 
Prof.  Prime's  Report,  D3,  Vol.  1,  already  mentioned  in  a 
preceding  chapter. 

I  have  no  doubt  that  a  shrewd  and  zealous  collector  would 
reap  a  plentiful  harvest  by  traversing  the  center  line  of 
Black  Log  valley  in  Huntingdon  county.  Good  collections 
could  be'made  in  Friend's  and  Milligan's  coves  in  Bedford, 
and  perhaps  around  the  edges  of  the  McConnellsburg  cove, 
and  along  Path  and  Horse  valleys  in  Fulton.  Trenton  fos- 
sils have  been  found  at  Chambersburg  in  Franklin. 


624  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 


Lituites  farnworthl,   Billings.    Pal.  Fow.  Vol.  1,  1861        Oncoceras  coMtrlcttun. 


Ormoceras  tenuifllum.     Hall,  PaL  N.  Y.  Vol.  1, 1849, 

~"          -': 


TSTO.  III.       UTICA   AND   HUDSON    RIVER.  525 


CHAPTER  XLV. 
Formation  No,  III.     Utica  and  Hudson  River  slate. 

The  age  of  limestone  which  has  been  described  in  the 
preceding  chapters,  was  followed  by  an  age  of  slate. 
Primeval  rivers  which  had  been  pouring  for  thousands  of 
years  their  lime  and  magnesian  waters,  nearly  pure  of  mud, 
into  the  Appalachian  sea,  thenceforward  for  other  thou- 
sands of  years  flowed  turbid  with  clays,  which  settled  to 
the  bottom,  blackened  with  the  decomposition  of  innumer- 
able animal  remains  mostly  of  microscopic  size.  At  first 
the  layers  of  clay  were  not  continuous  ;  thin  layers  of  lime- 
stone, or  rather  lime  shale  were  deposited  between  them  ; 
but  these  gradually  became  fewer  and  fewer,  and  in  the 
end  an  almost  continuous  deposit  of  very  slightly  calcareous 
mud  went  on.  At  long  intervals  and  apparently  only  in 
certain  parts  of  the  sea  bottom,  layers  of  very  muddy  lime- 
stone, 3  or  4  feet  thick,  were  made.  Toward  the  close  of 
the  age  another  change  took  place  in  the  character  of  the 
stuff  brought  down  by  the  rivers ;  their  mud  became 
coarser  by  an  admixture  of  fine  sand  ;  the  sand  increased 
in  size  and  quantity  ;  and  finally  became  the  prevailing 
sediment. 

Knowing  so  little  of  the  conditions  which  then  prevailed 
on  the  globe,  so  little  of  the  character  of  that  primeval  sea, 
and  of  the  continent  whose  rivers  furnished  it  with  stuff 
by  which  it  was  at  last  filled  up,  it  seems  audacious  to  at- 
tempt to  sketch  even  in  general  terms  the  sequence  of 
events,  a  picture  of  these  operations  of  Palaeozoic  history  ; 
and  every  sentence  of  the  sketch  is  liable  to  error.  For  no 
explanation  can  be  given  of  the  changes  by  land  and  sea 
which  produced  so  radical  a  change  of  deposits  as  that 
which  stares  the  geologist  in  the  face  wherever  he  crosses 
the  Great  Valley.  He  sees  6000  feet  of  the  slate  formation 


526 


GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 


XXX vnt 


NO.  III.       UTICA   AND    HUDSON    RIVER.  527 

No.  Ill,  in  Northampton  and  Lehigh  counties,  piled  upon 
3000'  of  the  limestone  formation  No.  II ;  but  it  is  left  to 
his  imagination  to  conjecture  what  stopped  the  deposits  of 
limestone  and  started  the  deposits  of  slate.  He  knows 
nothing  of  the  depth  of  the  sea  at  any  stage  of  that  his- 
tory.* He  knows  nothing  of  the  evenness  or  unevenness 
of  its  floor.  He  cannot  tell  at  what  distance  lay  the  con- 
tinental shores  from  which  issued  the  mighty  rivers  which 
furnished  the  sea  with  its  sediments  ;  nor  how  the  general 
level  of  the  ocean  rose  or  fell  upon  those  shores,  now  re- 
moving them  to  a  greater  distance,  or  now  bringing  them 
nearer.  He  only  sees  that  the  bottom  slates  of  Formation 
No.  Ill  (Utica  slate),  were  precipitated  as  black  mud  ;  and 
that  the  rest  of  the  6000  feet  (Hudson  River  slate)  is  made 
up  of  thin  layers  of  fine  shale,  of  various  tints  of  gray, 
with  a  few  layers  of  impure  limestone  in  Dauphin  and 
Cumberland  counties,  a  remarkable  set  of  gravel  beds  in 
Lehigh  county,  and  a  whole  series  of  roofing  slates,  with 
coarser  sandy  beds,  toward  the  top. 

One  extraordinary  part  of  this  obscure  history  rivets  our 
attention. 

Taking  the  two  formations  together,  that  is,  measuring 
the  whole  thickness  of  their  sediments  from  the  bottom  of 
the  limestone  to  the  top  of  the  slate,  on  the  Lehigh  and 
Delaware  rivers,  we  have  between  seven  and  eight  thousand 
feet  of  strata.  Doing  the  same  in  Nittany  valley  on  the 
upper  Juniata,  we  have  the  same  amount.  And  yet  meas- 
uring the  two  formations  separately  we  see  that  while  No. 
II  is  say  2000'  on  the  Lehigh  and  over  6000'  on  the  Ju- 
niata, No.  Ill  is  6000'  on  the  Lehigh  and  only  1000  on  the 
Juniata.  Incautious  geologists  would  pass  lightly  over  so 
wonderful  a  phenomenon  by  simply  pronouncing  that  talis- 
manic  word  non-conformability;  or,  perhaps,  giving  it  a 
little  more  consideration,  would  content  themselves  with 

*The  Cincinnati  (Hudson  river)  shale  and  limestone  beds  are  supposed 
to  have  been  deposited  in  shallow  water.  This  is  the  opinion  of  Dr.  New- 
berry,  Prof.  Shaler  and  Prof.  J.  F.  James.  Mr.  N.  W.  Perry's  article  in  the 
American  Naturalist,  Dec.  1889,  illustrated  with  phototypes  of  rain  marks, 
ripple  marks  and  mud  cracks  of  the  most  characteristic  kind,  explains 
them  as  made  over  the  gradually  sinking  bottom  of  a  shallow  sea. 


528  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 


Constellaria(Stellipora)antheloidea.  Monticulipora  James: 


Jtid.  1882.      f/9.5.      PL  XI 

Monticulipora  frondosa,  D'Orbigny      Colleti 


i   I   IP 


NO.  III.       UTICA   AND    HUDSON   RIVER.  529 

suggesting  some  oscillation  of  the  sea  bottom,  without  being 
able  to  explain  how  that  oscillation  could  produce  the  ef- 
fect. Both  formations  spread  throughout  the  United  States. 
But  their  thickness  in  Pennsylvania  is  diminished  to  one- 
third  in  the  western  States.  There  continental  source  would 
therefore  seem  to  have  been  in  the  far  east.  Seeing  that 
mud  is  the  usual  contribution  of  rivers  to  the  sea,  and  that 
therefore  the  slate  Formation  No.  Ill  would  probably  be 
thicker  at  the  east  than  at  the  west,  one  might  be  inclined 
to  regard  the  limestone  formation,  which  is  so  much  thicker 
in  Middle  Pennsylvania  than  in  the  Great  Valley,  as  a  pro- 
duct of  the  sea  itself,  and  not  of  the  rivers  of  a  bordering 
though  perhaps  distant  continent.  Such  in  fact  is  the  con- 
viction of  many,  some  of  whom  regard  all  limestone  beds  as 
chemical  deposits  from  standing  water ;  while  others  re- 
gard them  as  made  up  entirely  of  the  solid  parts  of  ani- 
mals inhabiting  the  sea,  dying  in  it  and  sinking  to  the  bot- 
tom. But  reasons  have  been  given  in  a  preceding  chapter 
for  rejecting  both  these  views ;  at  all  events  without  in- 
cluding the  action  of  inflowing  river  sediments.  The  fact 
is  that  our  science  is  as  yet  at  fault  in  its  discussion  of 
this  and  other  kindred  subjects. 

The  shape  and  size  of  the  Appalachian  sea  at  the  close 
of  the  limestone  age  were  undoubtedly  greatly  modified  by 
physical  movements  in  the  crust  of  the  earth  supposed  to 
be  then  going  on  in  eastern  New  York  along  the  Hudson 
and  Mohawk  valleys.  Around  the  escarpment  of  the  Cats- 
kill  mountains  the  slate  formation  No.  Ill,  and  the  suc- 
ceeding formations  No.  IV  and  No.  V  are  so  thin  as 
scarcely  to  be  visible  ;  and  this  can  hardly  be  explained  on 
any  other  hypothesis  than  that  of  an  upward  movement  of 
the  land,  temporary  or  otherwise,  and  the  contraction  of 
the  eastern  and  northern  borders  of  the  sea.  Such  a  move- 
ment in  that  region  could  hardly  have  taken  place  without 
a  more  or  less  general  elevation  of  the  sea  bottom,  and  a 
shallowing  of  its  water-basin,  bringing  the  top  of  its  lime- 
stone deposits  nearer  to  the  surface  of  the  water.  This 
may  perhaps  set  us  on  the  track  of  a  future  satisfactory 
explanation  of  the  wonderful  change  from  reputed  deep- 
34 


630  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 


.  Ill  a,  ^iitiaz  awi  IRb, 


JU.&i'tX.ttJ&fl 

ius.  juveni».     (Hall 

1»>.  

__  7al.Oh,B.Val.Z. 

Olyptocrinus  decadactylue. 
omatopora  densum.     (Syringoitroma^      ^\j/ffifa          ^  omntopora  (Aleeto)  frondosa.    Nichol»o.    (Av 

III  a. 


Graptolithus  divaricatus.     Hall.  Pal.   N.   Y.,  Vol.  HI, 


Graptolith 


>v<« 

I.  in*          Graptolithua  gncilit.    Hall.  Pal.  N.  Y.,  Vol.  Ill,  p. 
jli.     Ilr.ll.  Canada  Rt.,  1858,  Pal.,  N.  Y™ 


NO.  III.       UTICA   AND   HUDSON    RIVER.  531 

sea  limestone  deposits  to  reputed  shallow-water  shale  and 
slate  deposits.  But  it  still  leaves  to  he  considered  the  im- 
portant fact  that  6000  feet  of  the  shale  formation  No.  Ill 
was  laid  down  in  reputed  shallow  water.  If  we  adopt  that 
explanation  we  must  conclude  either  that  a  shallow  sea  can 
be  nevertheless  as  much  as  6000  feet  deep,  and  still  receive 
near  shore  deposits  ;  or  else  that  any  rapid  upward  move- 
ment at  the  end  of  the  limestone  age  must  have  lasted  but 
a.  comparatively  short  time,  and  was  followed  by  a  long 
slow  downward  movement  of  the  sea  bottom  to  receive  the 
6000  feet  of  slate.  It  will  be  seen  hereaftei*,  in  describing 
the  successive  formations  from  No.  IV  to  No.  XVII,  that 
such  a  downward  movement  did  in  fact  take  place,  contin- 
uously, or  by  successive  instalments,  and  at  varying  rates, 
through  the  whole  series  of  Palaeozoic  ages  to  the  end  of 
the  Coal  age. 

The  darkness  which  covers  this  whole  subject  is  still  further 
increased  by  our  insufficient  knowledge  of  the  effects  pro- 
duced long  afterwards  upon  the  condition  of  the  Palaeozoic 
formations  by  the  great  earth  movements  in  the  Mesozoic 
ages ;  for  many  of  the  phenomena  usually  considered  as 
falling  under  the  head  of  originalnon-conforinability\&.\v 
been  produced  by  the  crushing  and  faulting  of  formations 
beneath,  against  and  over  each  other.  It  has  been  rather 
too  rashly  asserted  that  the  limestone  beds  of  No.  II  in 
Pennsylvania  along  the  Great  Valley  were  plicated  and 
lifted  out  of  water,  and  subjected  to  the  erosion  of  atmos- 
pheric agencies,  and  then  resubmerged  and  covered  over 
non-con  formally  by  the  slate  beds  of  No.  III.  The  old  and 
recent  surveys  of  the  Great  Valley  show  that  there  is  no 
sufficient  ground  for  such  an  assertion.  On  the  contrary, 
wherever  the  contact  of  the  upper  beds  of  II  with  the  lower 
beds  of  III  are  exposed  to  observation  they  are  seen  to 
overlie  each  other  in  uninterrupted  sequence  as  if  they 
were  beds  of  one  formation.  Along  the  middle  line  of  the 
Great  Valley  however,  from  the  Delaware  to  the  Susque- 
hanna,  the  contact  is  obscured  by  the  crushed,  folded  and 
overturned  condition  of  the  rocks.  But  from  the  Susque- 
hanna  to  the  Potomac  the  contact  line  can  be  studied  with 


GEOLOGICAL   SURVEY    OF   PENNSYLVANIA. 


JfoJUI&tuxt 


XXXXJ. 


Diplograptus  (Graptolithus)  anpistifoiius,  Diplograptus  (Graptolithui)  spinulosns. 

"""  1      H*Dal!.        D1Plo»Paptus  (Graptolithus)  marcldus  •     **^lfcr        Diplograptus  (Graptolithus)  whltfleldi. 
-"K       A  Till',        Diplograptns  prUUs. 


Or»ptolithu«  multifaMiculat         Thamnograptus  capillaris.          Graptolithua  divergen 


Ehynchonella  capax  ( Atrypa  capo, ;  Conrad. .  Ehynchonella  P  modesta,        Rhynchonella  antlcosti 


(?  ^"""y"")  neglect* 


ahecuba,  Bill     strophomena  (aJ(»rna(a,  Mr.)  na«uta 
IB    :::  .......  I 


J    * 

•3F        ** 


a     IW3..         "^llBfc 


NO.  III.       UTICA   AND   HUDSON   RIVER.  533 

comparative  ease  ;  and  in  the  bends  of  Conodoguinet  creek 
the  upper  limestones  of  No.  II  are  seen  changing,  by  a  sys- 
tem of  alternations  nearly  a  thousand  feet  thick,  into  the 
lower  beds  of  No.  III.  These  alternations  of  thin  lime- 
stones, lime  shales  and  clay  shales  are  called  the  passage 
beds  of  No.  II  and  III ;  and  they  occupy  in  that  region  the 
place  in  the  series  which  the  Utica  shale  division  of  No. 
Ill  occupies  elsewhere. 

In  Franklin  county  the  superposition  of  No.  Ill  on  No. 
II  can  be  studied  to  great  advantage  by  means  of  the 'four 
anticlinal  belts  of  II  sustaining  synclinal  belts  of  III,  as 
more  fully  described  in  Chapter  XXII,  page  288,  above.  In 
Berks  county  the  same  fact  is  made  clear  in  another  way, 
as  the  limestone  belt  west  of  the  Schuylkill  is  set  with 
parallel  synclinal  slate  ridges  lying  in  long  narrow  troughs 
of  the  limestone.  In  Lehigh  county  we  have  the  best  of 
these  exhibitions  in  Huckleberry  ridge.  Here  the  front 
edge  of  the  slate  belt  at  Foglesville  runs  forward  6  miles  to 
a  sharp  point  within  2  miles  of  the  Lehigh  river  at  Allen- 
town,  while  a  great  cove  of  limestone  behind  it  encloses  the 
Ironton  mines.*  All  these  isolated  streaks  and  spurs  of 
the  slate  No.  Ill  in  the  limestone  valley  of  No.  II  are  so 
many  separate  proofs  that  the  slate  formation  overlies 
regularly,  and  conformably  the  limestone  formation  No.  II. 

This  condition  of  things  becomes  still  plainer  when  we 
leave  the  Great  Valley  to  study  the  two  formations  in  the 
interior  valleys  of  Middle  Pennsylvania. 

Path  valley  in  Franklin  county  serves  as  a  link  of  con- 
nection between  the  interior  mountain  country  and  the 
Great  Valley,  into  which  Path  valley  opens  at  its  southern 
end.  The  McConnellsburg  cove  in  Fulton  county  is  the 
first  completely  isolated  uprise  of  the  limestone  back  of  the 
North  mountain  and  is  surrounded  by  a  border  of  overlying 
slate.  Horse  valley  in  Perry  county  is  almost  entirely 
floored  with  slate.  A  border  of  slate  entirely  surrounds  the 
central  limestone  floor  of  KisJiicoquiUis  valley  with  its 
three  parallel  slate  prongs  towards  the  east.  A  similar 
border  of  No.  Ill  slate  entirely  surrounds  the  irregular 

*See  description  in  Chapter  XXX,  page  347,  above. 


534  GEOLOGICAL    SURVEY    OF   PENNSYLVANIA. 


.  Ilia,  fyfjUCd,  and  III  I,  ^i 


Lyrodesma  poststriatum.     ( Xueulana  pothriata. )  E. 

"Uo'T™rr^>.!"    '«i    o          '"        yNw-1-'2 

Ct  ^>^<^. 


110^^4 


NO.  III.      UTICA   AND   HUDSON    RIVER.  535 

limestone  area  of  Penn,  Brush,  Nittany,  Sinking  Spring, 
Canoe  and  Morrison  valleys.  Similar  slate  rings  surround 
the  limestone  of  Nippenose  and  Mosquito  valleys  in  Ly- 
coming,  and  Friends  and  Milligari's  coves  in  Bedford. 
All  these  outcrops  of  No.  Ill  show  the  slate  to  be  about 
1000  feet  thick,  resting  conformably  upon  the  top  beds  of 
Trenton  limestone,  and  descending  conformably  beneath  the 
surrounding  sandstone  mountains  of  No.  IV.  It  may  be  af- 
firmed with  confidence  that  in  no  part  of  the  world  is  there 
a  more  satisfactory  exhibition  of  regular  conformity  in  the 
superposition  of  one  great  formation  upon  another  over  an 
extensive  region. 

The  attention  of  the  reader  is  directed  to  the  fact  that  all 
the  valleys  floored  with  No.  II  and  surrounded  by  a  contin- 
uous outcrop  of  No.  Ill,  as  described  above,  are  in  counties 
of  middle  Pennsylvania  lying  west  of  the  Susquehanna 
river;  for  neither  the  limestone  nor  the  slate  reaches  the 
present  surface  of  the  State  anywhere  east  of  the  Susque- 
hanna river,  except  in  the  Great  Valley.  When  No.  Ill 
goes  down  for  the  last  time  along  the  south  foot  of  the  Bald 
Eagle  mountain  in  Centre  county,  and  Dunnings  mountain 
in  Blair  county,  it  does  not  rise  again  until  we  reach  Cin- 
cinnati on  the  Ohio  river,  where  the  slare  formation  has  re- 
ceived from  the  Ohio  geologists  the  name  of  the  Cincinnati 
group.  Its  northern  outcrop,  exposed  in  Canada,  but  con- 
cealed beneath  the  waters  of  Lake  Ontario,  appears  at  the 
western  foot  of  the  Adirondack  mountains  in  northern  New 
York,  and  in  the  lower  Mohawk  valley,  where  it  received 
nearly  fifty  years  ago  the  name  Loraine  s7ial.es  and  Utica 
slate.  From  Albany  south  it  was  named  the  Hudson  River 
slate,  a  name  by  which  it  has  been  commonly  known  in 
American  geology,  and  by  which  it  has  been  habitually 
designated  in  all  the  reports  of  the  Pennsylvania  Geological 
Survey  since  1874.  The  name  of  Naslimlle  group  was  given 
to  it  by  the  Geological  Survey  of  Tennessee,  around  the 
central  area  of  which  its  outcrop  describes  a  great  ring. 

Along  the  southern  extensions  of  its  outcrop  No.  Ill 
exhibits  a  remarkable  change  of  color  soon  after  passing 
out  of  Pennsylvania  into  Virginia,  becoming  so  red  by  ex- 


536  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 


F777 


S.Itta.  Qttica,  and  .Ulb.^&usUon  riveiiconJM. 


Modiolopsis  anodontoides 


Cyrtolites  ornatus.    Rogers,  page  821,  fig.  61 


Bucania   rugos         Cyclonema  bilix 


hisonia  turricula.       Murchisonia  gracilts.         Murchisonia  gracilis 

f.o  -.-rz.  -'  ~~\  in  t,. 

EM. 


Microdiscuo  quadricostatus, 


Proetus  spurlocki  Proetus  parviuscu 


Menocephalus  globosus,  "'  ''^~ 


Triarthrus  glaber,  Triarthrus  spinosu 


NO.  III.      UTICA   AND    HUDSON   RIVER.  537 

posure  to  the  atmosphere  as  to  give  the  slopes  of  the  mount- 
ains into  which  it  sinks  a  reddish  soil;  indicating  a  much 
larger  percentage  of  disseminated  iron  pyrites  throughout 
the  mass  than  in  Pennsylvania.  From  the  Hudson 
river  northward  through  Vermont  into  Canada  the  slate 
beds  also  exhibit  an  extra  percentage  of  sulphide  of  iron; 
but  in  that  region  the  pyrites  instead  of  being  distributed 
microscopically  through  the  slate  is  concentrated  into  mil- 
lions of  separate  beautifully  perfect  individual  cubes,  of  all 
sizes  from  a  half  inch  down  to  the  tenth  of  an  inch.  Long 
exposed  surfaces  of  these  Vermont  slates  are  pitted  with 
square  holes  from  which  the  crystals  of  pyrites  have  been  re- 
moved by  solution.  In  the  roofing  slate  belt  of  eastern  Penn- 
sylvania such  crystals  are  frequently  seen;  and  some  of  the 
beds  are  rendered  worthless  to  the  quarrymen  by  the  quan- 
tity of  microscopic  pyrites  which  they  contain;  others  seem 
to  be  almost  perfectly  free  from  this  noxious  adulteration. 
One  of  the  sources  of  the  pyrites  was  no  doubt  an  infu- 
sion of  sulphate  of  iron  poured  into  the  sea  by  primeval 
rivers.  But  we  must  ascribe  the  special  abundance  of  py- 
rites in  certain  parts  of  the  formation,  in  certain  beds,  and 
at  certain  localities,  to  some  more  restricted  cause  ;  and  we 
know  of  no  other  special  cause  than  that  of  the  secretion 
of  sulphur  in  the  tissues  of  animals  and  plants,  especially 
of  sea  weed  vegetation.  The  accumulation  of  sea  weed  on 
a  shore  will  always  furnish  a  considerable  amount  of  iron 
pyrites  to  the  shore  sands  ;  and  consequently  to  the  deposits 
of  the  sea  bottom  in  the  neighborhood.  We  have  a  right 
to  suppose  that  the  general  distribution  of  iron  pyrites 
through  the  slates  of  No.  Ill  testify  to  the  existence  of 
marine  plants  in  great  abundance  in  that  age,  even  were 
no  traces  of  the  existence  of  such  plants  preserved  as  col- 
ored impressions  on  the  surface  of  the  slates.  We  are, 
however,  not  left  to  any  vague  speculation  on  this  subject. 
The  remains  of  plants  have  been  collected  from  the  New 
York  outcrop  of  No.  Ill  and  described  and  figured  by  Pro- 
fessor Hall  under  the  names  Sphenothallus ,  Buthotrephis, 
and  Pal&opJiycus*  It  is  true  that  other  imprints  on  the 

^Palaeontology  of  New  York,  Vol.  1,  1847,  pi.  68,  69  and  70. 


538  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

slates  have  been  described  and  figured  as  plants  which  are 
now  believed  with  good  reason  to  be  merely  markings  left 
by  wriggling  worms,  crawling  crustaceans,  and  locomotive 
shellfish  ;  yet  this  does  not  invalidate  the  plant  character 
of  the  remainder  ;  and  we  cannot  imagine  a  sea  inhabited 
by  animals,  even  of  the  lowest  grade,  without  the  co-exist- 
ence of  a  world  of  marine  plant  life  on  which  these  ani- 
mals could  feed. 

One  of  the  most  curious  facts  connected  with  the  expo- 
sures of  No.  Ill  is  the  occurrence  in  some  places  of  streaks 
and  nuts  of  a  sort  of  anthracite  coal.  Such  nuts  of  coal,  as 
large  as  a  hen's  egg,  have  been  picked  out  from  between  the 
slates  of  No.  Ill  on  the  side  of  Cove  mountain  in  Franklin 
county.  Their  composition  will  be  given  in  another  place. 
Their  origin  is  quite  unknown  ;  they  have  no  connection 
whatever  with  beds  of  coal ;  they  have  not  been  transported, 
but  were  made  in  the  place  where  they  were  found ;  they 
are  disconnected  also  from  each  other  ;  they  appear  to  be 
concretions  or  small  accumulations  of  nearly  pure  carbon  ; 
and  their  genesis  is  probably  connected  in  some  manner 
with  that  general  distribution  of  carbon  through  the  slate- 
mud  which  has  given  so  many  of  the  beds  of  the  formation 
a  black  or  blue-black  color. 

Besides  the  markings  made  by  animals  and  the  impres- 
sions left  by  plants  there  is  a  third  kind  of  fossil  forms  in 
No.  Ill  of  the  greatest  interest  to  the  geologist.  Some  of 
the  slate  beds  are  made  up  of  innumerable  paper-like  layers 
of  slate  connected  together ;  and  on  the  surface  of  these 
black  films  of  mud  appear  millions  of  markings  resembling 
scattered  straw,  and  bits  of  black  thread.  Most  of  them 
are  fragments  of  some  living  organisms  which  at  first  sight 
would  be  taken  for  the  thin  stems  of  plants.  Others  are 
arranged  together  in  regular  forms  radiating  from  a  center 
or  with  a  center  line  forked  at  both  ends,  the  end-forks 
forking  again.  Some  of  these  kinds  have  all  their  forks 
connected  by  a  delicate  almost  invisible  membrane,  like  an 
old  umbrella  with  its  ribs  sticking  out  beyond  the  edge  of 
the  silk.  Others  are  like  oval  leaves  pointed  at  both  ends 
and  with  radiating  nerves,  the  ends  of  which  project  all 


NO.  III.       UTICA   AND   HUDSON   RIVER.  539 

round  beyond  the  edge  of  the  leaf.  Most  of  those  which 
are  single  fragmentary  threads  or  narrow  ribbons  have  one 
edge  delicately  toothed  from  end  to  end  ;  some  are  toothed 
on  one  edge  toward  one  end  and  on  the  opposite  edge  toward 
the  other  end.  Some  have  both  edges  set  with  fine  saw 
teeth  ;  and  it  becomes  evident  that  many  which  seem  to  be 
toothed  only  on  one  edge  have  been  folded  along  the  mid- 
dle so  as  to  bring  all  or  some  of  the  teeth  of  both  edges  to 
one  side.  Large  collections  of  these  Graptolites  have  been 
made  both  in  Europe  and  America,  and  subjected  to  the 
closest  examination  and  comparison.  It  is  quite  certain 
that  these  little  creatures  were  a  peculiar  kind  of  floating 
animal,  but  nearly  as  low  in  the  grades  of  life  as  plants  ; 
that  they  grew  from  living  specks,  as  the  leaves  of  a  tree 
grow  from  buds ;  and  that  they  produced  at  first  a  foot 
stalk,  which  expanded  and  multiplied  itself  and  became 
gradually  furnished  with  the  necessary  organs  of  nutrition 
and  reproduction.  A  great  number  of  separate  genera  and 
species  of  these  graptolites  existed  in  that  very  early  age 
of  the  world  ;  some  of  which  continued  to  exist  for  two  or 
three  ages  following,  and  then  this  whole  family  of  living 
creatures  disappeared  from  the  waters  of  the  world.  In 
the  age  of  No.  Ill  the  Appalachian  ocean  and  its  extension 
through  northern  Europe  was  alive  with  them,  incredible 
multitudes  floating  and  feeding  on  the  surface  and  sinking 
to  the  bottom  to  be  fossilized  in  the  slate-mud.  It  is  pro- 
bable therefore  that  the  prevailing  dark  color  of  our  roofing 
slates  and  other  beds  of  No.  Ill  should  be  ascribed  to  the 
vast  amount  of  carbon  secreted  by  the  graptolites,  and  at 
their  death  transferred  to  the  slate-mud  which  was  all  the 
time  accumulating  at  the  sea  bottom.  It  is  barely  possible 
(perhaps  if  we  knew  more  about  it  we  would  say  it  was 
quite  possible)  that  colonies  and  conglomerations  of  grap- 
tolites in  some  places  were  dense  enough  to  account  satis- 
factorily for  the  thin  streaks  and  nuts  of  coal  mentioned 
above.  We  may  imagine  that  the  graptolites  floated  mainly 
at  the  surface  of  the  water  and  received  the  principal  part 
of  their  sustenance  from  the  carbonic  acid  which  in  those 
early  ages  loaded  the  atmosphere  more  heavily  than  now  ; 


540  GEOLOGICAL   SURVEY    OF   PENNSYLVANIA. 

and  that  this  manner  of  feeding  brings  the  graptolite  life 
into  close  analogy  with  the  plant  life  of  all  ages,  the  leaves 
of  trees  receiving  their  sustenance  in  like  manner  from  the 
air ;  but  we  must  not  forget  that  microscopic  life  has  al- 
ways pervaded  the  world,  furnishing  the  chief  food  of  all 
lower  orders  of  creatures. 

The  relations  which  existed  between  these  curious  ani- 
mals, the  graptolites,  and  other  animated  inhabitants  of  the 
Appalachian  sea  the  solid  shells  of  which  are  also  abund- 
ant at  some  of  the  outcrops  of  Formation  No.  Ill  is  a  sub- 
ject of  mere  speculation.  Whether  the  graptolites  had  any 
intercourse,  friendly  or  hostile,  with  the  multitudes  of  free- 
floating  crinoids,  or  with  the  submarine  meadows  of  stone 
lilies  waving  their  calcareous  heads  upon  long-jointed  stalks 
rooted  in  the  mud,  and  spreading  their  locks  of  calcareous 
hair  abroad  in  search  of  microscopic  food,  we  cannot  tell. 
Nor  do  we  know  what  intercourse  there  was  between  these 
crinoidal  animals  and  the  innumerable  shell-fish  of  various 
classes,  kinds  and  species  which  then  lived.  A  great  vari- 
ety of  species  have  been  figured  and  described.  Most  of 
them  persisted  through  the  whole  slate  age,  then  perished  to 
be  seen  no  more  in  higher  formations;  so  that  a  collection  of 
fossils  of  No.  Ill  is  quite  sufficient  to  distinguish  this  forma- 
tion from  all  preceding  it  and  from  all  that  followed  it  in 
geological  history;  and  quite  sufficient  to  identify  the  out- 
crops of  No.  Ill  wherever  they  may  be  encountered  in 
Europe  or  America. 

The  amount  of  coralline  life  in  the  Utica  and  Hudson 
River  age  was  very  great  and  a  variety  of  beautiful  forms 
are  figured  by  Hall  in  plates  75  to  78  of  his  first  New  York 
volume,  and  by  Newberry  in  plates  1  to  4  of  the  first  volume 
of  the  Palaeontology  of  Ohio. 

A  considerable  variety  of  shells  have  also  been  preserved 
in  these  two  formations.  Among  BR  ACHIOPODS  were  species 
of  Lingula,  Leptaena,  Or  this,  Atrypa,  OrMcula,  Slropho- 
mena,  Zygospira.  Wiynchonella,  Retzia,  Nuculites,  Cypri- 
cardites,  Megambonia.  Of  LAMELLIBKANCHS  were  species 
of  Avicula,  Ambonycliicb,  Modiolopsis,  Orlhonola,  Lyro- 
desma.  Of  GASTEROPODS  there  were  species  of  Murcliisonia, 


NO.   III.       UTICA    AND    HUDSON    RIVER.  541 

Pleurotomaria,  Bellerophon,  Cyrtolites.  Among  CEPIIALO- 
PODS  were  species  of  Endoceras,  Orthoceras,  Ormoceras. 
Of  TRILOBITES  there  were  various  species  of  Dalmaniles, 
Acidaspis,  Ceraurus,  Proetus,  Asaphus,  Calymene. 

Previous  to  Dr.  Walcott's  publication  in  1890  of  his  dis- 
covery of  fisli  remains  on  the  Colorado  river  it  has  been  the 
opinion  of  all  geologists  that  no  vertebrate  animal  yet  existed. 
Not  a  trace  of  any  kind  of  fish  has  elsewhere  been  detected 
in  the  first  four  formations  of  the  Palaeozoic  series;  the 
earliest  known  fish-spine  was  found  by  Professor  Claypole 
in  one  of  the  beds  of  Formation  V,  in  Perry  county  (to  be 
noticed  hereafter);  nor  is  there  any  certain  evidence  of  the 
existence  of  land  plants.  As  the  corals  of  the  present  day 
pervade  the  trophical  belt  of  the  earth,  and  as  a  change  oi' 
temperature  of  a  few  degrees  is  known  to  produce  wide- 
spread destruction  among  the  finny  tribes  of  our  present 
sea,  the  abundance  of  coral  life  and  the  absence  of  fish  in 
the  early  ages  conspire  to  testify  to  a  high  temperature  of 
the  ancient  ocean  water;  and  this  agrees  with  our  supposi- 
tion of  the  gradual  cooling  of  the  globe. 

The  black  Utica  slate,  and  many  darker  layers  of  the 
Hudson  River  slate,  especially  in  the  western  States,  have 
been  so  heavily  charged  with  carbon  from  the  decayed 
bodies  of  the  creatures  which  filled  the  sea,  that  hand  speci- 
mens will  smoke  andtiame  in  a  blacksmith's  fire.  This  has 
given  them  the  mineralogical  name  of  fire  slate  (pyroschists). 

Dr.  Sterry  Hunt  in  his  Tenth  Chemical  Essay,  1875,  page 
178,  gives  analyses  of  Utica  slate  composed  of  53  to  58  per 
cent  of  carbonate  of  lime  with  a  little  magnesia  and  ox- 
ide of  iron;  the  insoluble  part  of  the  rock  lost  12.6  per  cent 
of  volatile  and  combustible  matters,  leaving  a  coal  black 
residue.  AVhen  this  was  heated  in  the  open  air  it  lost  8.4 
per  cent  additional,  making  in  all  21  per  cent  of  volatile 
and  carbonaceous  matter  in  the  rock.  Very  little  of  this 
however  was  bitumen;  the  most  of  it  was  of  the  nature  of 
a  true  coal.  Attempts  to  distill  oil  on  a  large  scale  from 
this  rock  resulted  in  the  production  of  only  from  3  to  5  per 
cent  of  oily  and  tarry  matter,  besides  combustible  gases 
and  water. 


542  GEOLOGICAL   SUKVEY   OF   PENNSYLVANIA. 

It  is  not  likely  that  the  black  slates  of  any  part  of  this 
great  formation  No.  Ill  will  ever  be  used  by  the  business 
world  for  the  distillation  of  oil,  or  the  production  of  illumi- 
nating gas. 

Such  pyroschists  or  black  slates  have  been  deposited  in 
all  ages.  It  will  be  shown  in  a  proper  place  that  they  are 
not  only  sometimes  very  rich  in  carbon,  but  interleaved 
with  thin  beds  of  coal,  deceiving  people  into  the  belief  that 
they  can  be  profitably  mined.  Such  is  the  case  especially 
with  the  black  slates  near  the  botton  of  Formation  No.  VIII 
on  the  Janiata  and  elsewhere  in  the  State.  It  will  also  be 
seen  that  such  pyroschists  usually  form  the  roof  of  every 
true  coal  bed  and  furnish  the  material  from  which  the  dis- 
tillation of  coal  oil  was  carried  on  previous  to  the  discovery 
of  petroleum.  But  in  the  upper  or  later  formations  the 
carbon  distributed  through  the  black  shales  was  certainly 
derived  in  large  part  from  water  plants  growing  in  pools 
surrounded  by  a  land  vegetation.  We  may,  therefore,  take 
it  for  granted  that  the  carbon  of  the  black  slates  of  forma- 
tion No.  Ill  was  obtained  also  from  the  destruction  of  some- 
kind  of  water  plant  vegetation,  but  mixed  with  the  decayed 
animal  tissues  of  shell-fish,  corals,  water-bugs  and  worms. 
It  will  be  shown  in  describing  the  Oil  Measures,  that  the 
quality  of  petroleum  obtained  from  formations  of  different 
ages  differs  greatly,  especially  in  odor;  and  this  is  part  of 
the  evidence  that  the  older  petroleums  are  of  animal  origin 
more  than  vegetable ;  and  that  the  newer  petroleums  (in 
Pennsylvania)  had  a  vegetable  rather  than  animal  origin. 

In  speaking  of  worm  tracks  as  abundant  in  No.  Ill  no 
mention  was  made  of  the  forms  of  the  worms  themselves ; 
for  it  can  be  readily  understood  that  such  soft  creatures, 
destitute  of  internal  skeletons  and  external  hard  coverings 
would  die  and  vanish  without  leaving  any  trace  except 
casts  of  their  barrows,  and  impressions  of  their  movements. 
This  is  true  of  the  whole  family  of  sea  slugs.  But  there 
were  in  the  Hudson  River  Age,  and  also  in  ages  subsequent, 
vast  numbers  of  leeches,  with  horny  plates  in  their  mouths 
set  with  little  tooth-like  conical  projections.  Multitudes 
of  the  shining  little  cones  (Conodonts,  see  Chapter  XLIV, 


JSTU.   III.       UTICA    AND    HUDSON    RIVER.  543 

page  507,  above)  have  been  found,  not  only  scattered  sep- 
arately, but  in  small  groups,  and  in  some  instances  attached 
to  fragments  of  the  horny  plates  on  which  they  were  set. 
What  these  leeches  lived  on  is  an  interesting  question. 
They  are  found  scattered  over  surfaces  of  slate  on  which 
appear  worm  tracks  which  were  probably  made  by  the 
animal  that  owned  the  teeth.  But  the  size  of  the  animal 
and  the  efficient  character  of  its  biting  apparatus  would 
lead  us  to  suppose  that  there  existed  then  sea  animals  of  a 
considerable  size  clad  in  succulent  flesh  ;  yet  no  remains  of 
that  kind  have  been  discovered. 

The  few  limestone  beds  which  are  locally  interstratified 
with  the  slates,  as  in  Dauphin  county,  are  too  thin  and 
muddy  to  make  them  deserving  of  serious  mention  in 
economical  geology  ;  especially  seeing  that  they  crop  out 
within  two  or  three  miles  of  the  north  edge  of  the  limestone 
belt  of  the  Great  Valley.  In  the  outcrops  of  No.  Ill 
around  the  isolated  limestone  valleys  and  coves  of  Middle 
Pennsylvania  also  such  interstratified  thin  limestones  have 
been  occasionally  observed.  As  for  example  on  the  slopes 
above  Spring  Mills  in  Southern  Centre  county  (426,  T4). 
As  there  are  no  iron  ore  beds  in  No.  Ill,  nor  any  other 
metalliferous  beds,  this  formation  is  of  no  mineral  value 
throughout  the  greater  part  of  the  State.  Its  soil  is  dis- 
posed to  be  cold  and  wet ;  but  otherwise  sufficiently  fer- 
tile ;  so  that  the  No.  Ill  slopes  of  Bald  Eagle,  Tussey, 
Shade,  Black  Log,  Tuscarora,  North  and  Blue  mountains 
are  farmed  by  a  large  number  of  landholders,  the  fields  ex- 
tending half  way  up  the  mountain  side  (T4,  425). 

The  roofing  slate  belt. 

In  one  part  of  the  State,  however,  Formation  No.  Ill  is 
of  great  mineral  value,  furnishing  the  finest  quality  of 
roofing,  table,  and  school  slates. 

The  roofing  slate  belt  of  No.  Ill  runs  from  the  Delaware 
to  the  Schuylkill,  through  the  northern  townships  of 
Northampton,  Lehigh  and  Berks,  where  large  settlements 
of  slate  workers  have  opened  extensive  quarries,  and  built 


GEOLOGICAL   SURVEY    OF   PENNSYLVANIA. 


NO.  III.'     I    PICA    AND    HUDSON    RIVER. 


545 


nal  ^Report,  Vol.1, 1831 

Slalingtoii  section.  pL  L, 

(D3  page  13o.) 


Small  bed* (containing  some 
Large  beds.) 

400        Inrlndrx  l/ir  uuarrij  beds  around 
Hcinbftck.f,  and  around  Slatedale; 
exact  position  unknown. 


08    3)  3D.  5ont6  '  roofing  slate  quarries 
100' 

(jo7    WeUhtQOtn  rooting  slate  quarries. 
i$LJ  J    J  / 

100 

uarries 


1L/       114       franklin  roofing  slate  quarri 

gn  ;i¥ 


100 


,,'   Scimesffiess  %  Cos  slate 

(Blue  vein.   Washington   cLuarri 


210 


rcmjinq  slate 


The 


liio*   /3l/M>  mountain  (junrnj. 


35 


546  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

considerable  towns  connected  by  railroads.  This  district 
is  to  Pennsylvania  what  North  Wales  is  to  Great  Britain  ; 
and  in  the  course  of  time  the  quarries  of  Slatington  on  the 
Lehigh  and  Bangor  on  the  Bushkill  will  become  as  worthy 
of  the  pilgrimage  of  geologists  and  tourists  as  the  Welsh 
slate  quarries  of  Tremadoc.  Dr.  Chance,  in  Report  of  Pro- 
gress D3,  Vol.  I,  1883,  describes  more  than  a  hundred  slate 
quarries,  old  and  new,  some  abandoned,  many  vigorously 
worked,  illustrating  his  descriptions  with  photographic 
views  of  the  older  and  deeper  quarries,  and  giving  many  sec- 
tions of  the  beds  in  which  the  workings  are  carried  on.  The 
section  along  the  Lehigh  at  Slatington  (D3,  page  147)  shows 
the  folded  structure  of  the  formation  and  the  order  in 
which  the  principal  valuable  beds  of  slate  occur.  The 
measured  thickness  of  the  roofing  slate  part  of  the  forma- 
tion amounts  to  1529  feet,  divided  up  into  small  and  large 
slate  beds,  separated  by  groups  of  beds  which  are  not  fit  to 
quarry  (page  135).  See  plates  L  and  LI. 

The  groups  of  beds  that  are  worked  may  be  thus  de- 
scribed. Group  A  (at  the  bottom),  12  feet ;  Group  B,  25 
feet ;  Group  C,  12  feet ;  Group  D,  60  feet ;  Group  E,  50 
feet ;  Group  F,  12  feet.  Groups  A  and  B  are  only  16  feet 
apart ;  C  is  222  feet  above  B,  and  separated  from  D  by  only 
15  feet ;  D  from  E  by  12  feet ;  E  from  F  by  73  feet.  But 
these  only  represent  beds  that  have  been  successfully 
worked  on  the  Lehigh  river.  Many  others  have  been 
opened  and  tested  but  not  worked. 

In  a  general  way  it  may  be  said  that  the  upper  beds  of 
slate  run  parallel  with  the  foot  of  the  Blue  mountain,  at  a 
distance  of  from  half  a  mile  to  a  mile  from  it.  The  out- 
crop of  the  lowest  beds  runs  rudely  parallel  with  the  other 
at  a  distance  of  from  half  a  mile  to  a  mile  further  south. 
These  variable  distances  from  the  Blue  mountain  and  from 
each  other  are  in  consequence  of  the  folded  condition  of  the 
formation,  bringing  up  the  same  beds  to  the  surface  in 
small  and  large  waves  again  and  again.  The  slate  quarries 
furnish  fine  opportunities  for  studying  the  character  and 
quantity  of  the  earth  movement  which  has  thrust  the  whole 
country  northward.  In  no  other  part  of  the  slate  belt  No. 


NO.  Til.       UTICA   AND   HUDSON    RIVER.  547 

III  from  the  Delaware  to  the  Potomac  can  the  exact  quan- 
tities of  its  folding  be  obtained  ;  but  the  openings  in  Lehigh 
and  Northampton  are  so  large  and  numerous,  and  so  close 
together,  that  transverse  sections  can  be  constructed  with- 
out much  difficulty,  and  the  shape  of  the  plications  can  be 
represented  to  the  eye  (as  in  plate  L). 

It  must  not  be  supposed  that  the  slates  sent  to  market 
are  the  original  laminae  of  the  beds  deposited  one  above 
the  other  and  split  asunder.  The  beds  of  the  formation 
will  not  thus  split.  Although  originally  deposited  in  leaves 
or  thin  sheets  of  mud  these  original  layers  have  been  com- 
pacted into  a  solid  mass  and  cannot  now  be  separated  by 
human  tools.  Even  if  they  could  be  so  separated  they 
would  be  useless  to  man,  because  they  are  bent  into  curves. 
Fortunately  for  our  arts  of  life  the  pressure  which  folded 
the  beds  produced  another  and  very  remarkable  effect  upon 
them.  Being  a  great  and  uniform  pressure  from  the  south 
toward  the  north,  it  subdivided  the  whole  formation  into 
millions  of  thin  plates,  perpendicular  to  the  direction  of 
the  pressure  ;  and  these  are  the  plates  which  are  split 
asunder  by  the  quarrymen  and  sold  for  various  purposes. 
Thus  we  have  curved  planes  of  original  stratification,  and 
straight  smooth  planes  of  pressure-foliation.  The  most 
striking  feature  of  the  slate  quarry  to  the  eye  of  a  spectator 
is  this  double-banded  structure  of  the  rocks.  He  sees  the 
face  of  the  quarry  crossed  by  the  foliation  in  straight 
lines,  seldom  vertical,  but  usually  dipping  steeply  toward 
the  south  ;  and  the  quarry  operations  follow  these  bands 
and  pay  no  attention  whatever  to  the  original  stratified 
beds  of  the  formation.  Across  the  bands  of  foliation 
the  curved  ribbons  of  the  folded  strata  are  seen  passing 
from  one  side  of  the  quarry  to  the  other  in  a  series  of 
waves,  each  stratum  distinguished  from  the  strata  above 
and  below  it  by  either  strong  or  delicate  differences  of  color. 
Every  one  must  have  noticed  in  rooting  slates,  and  some- 
times in  writing  slates,  bands  of  a  lighter  or  darker  tint 
crossing  them  ;  these  reveal  the  original  sedimentation. 
Every  one  must  have  noticed  on  dark  writing  slates,  whitish 
spots,  and  that  the  slate  pencil  when  it  leaves  the  black 


548  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 


,'sm 

i  Xuadn  Quarry.  M.S  Z.  KJlaiinuS  Quarry,  X,  £. 


3.  SSayaf  Quarry,  X.  Si.         4. Tallin ftm  Quary,  76  fc 


NO.   III.       UTICA    AND   HUDSON   RIVEIl.  549 


,  Matec/uam^  on 


550  GEOLOGICAL    SURVEY    OF    PENNSYLVANIA. 

surface  and  crosses  such  a  white  spot  will  not  bite.  These 
white  spots  are  small  pellets  of  clay  in  the  original  sedi- 
ment mashed  flat  and  enlarged,  and  reduced  to  an  exceed- 
ing thinness  by  pressure.  See  plates  XXXVIII,  XXXIX. 

Another  interesting  phenomenon  connected  with  the 
planes  of  foliation  is  their  frequent  fan-shaped  structure, 
especially  where  the  original  beds  are  sharply  bent  upon 
themselves  ;  for,  since  the  foliation  was  produced  by  pres- 
sure, and  in  planes  perpendicular  to  that  pressure,  when- 
ever the  mass  was  sharply  bent  the  direction  of  the  pres- 
sure was  modified  on  the  two  sides  of  the  fold,  causing  the 
planes  of  foliation  to  diverge.  This  will  be  sufficiently  ex- 
plained in  a  more  detailed  description  of  the  slate  region. 

As  the  development  of  the  cleavage  planes  or  slate  foli- 
ation was  produced  by  the  pressure  expended  by  an  earth- 
movement  from  the  south,  and  as  the  amount  of  this  move- 
ment must  have  been  measured  by  the  number  and  sharp- 
ness of  the  anticlinal  and  synclinal  rock-folds  which  re- 
sulted from  it,  we  should  expect  the  greatest  amount  of 
foliation,  that  is,  the  greatest  number  of  workable  slate  beds 
to  be  in  districts  where  folds  are  most  numerous.  At  the 
first  glance  this  would  seem  to  explain  the  fact  that  there 
are  only  two  workable  slate  beds  on  the  Delaware  river,  for 
there  the  whole  mass  of  Formation  No.  Ill  slopes  north- 
ward in  a  very  regular  way,  with  dips  of  20°  increasing  to 
35°  at  the  top  (in  the  Delaware  Water  Gap)  where  the  upper- 
most Hudson  River  beds  are  seen  going  down  beneath  For- 
mation No.  IV. 

On  the  Delaware  river  there  is  an  almost  total  absence  of 
the  sharp  small  rolls  and  basins  which  are  so  prominent  a 
feature  on  the  Lehigh  river;  and  this  has  given  an  oppor 
tunity  for  a  fair  measurement  of  the  thickness  of  the  forma- 
tion north  of  the  great  anticlinal  which  crosses  the  river 
about  2  miles  south  of  the  Gap.  Its  upper  series  of  beds' 
measured  from  the  base  of  No.  IV  down  to  Williams'  old 
slate  quarry  count  up  say  1540  feet;  the  lower  series  meas- 
ured from  Shocks  down  to  Belvidere  counts  up  say  3700 
feet;  the  total  of  5240  feet  ought  probably  to  be  increased 
to  6000. 


NO.   III.       UTICA    AND    HUDSON    RIVER.  551 

The  upper  series  consists  of  beds  which  are  commonly 
more  than  one  foot  thick;  and  the  lower  series,  of  beds 
which  are  usually  less  than  one  foot  thick  (Sanders'  report 
in  D3,  page  85).  An  independent  set  of  measurements 
along  the  Delaware  river  gives  an  equally  large  estimate, 
and  places  the  two  slate  quarry  beds  at  1000  feet  and  2350 
feet  respectively  beneath  the  base  of  No.  IV  (Chance's  re- 
port).* These  five  or  six  thousand  feet  of  rocks  consist  of 
beds  of  slate  varying  in  thickness  from  only  one  hundredth 
of  an  inch  up  to  a  maximum  of  at  least  30  feet;  being  nearly 
all  of  them  of  a  dark  grey  bluish  black  color;  some  of  them 
of  very  fine-grain  ;  others  coarser ;  and  some  coarse  enough 
to  be  considered  sandstone,  but  not  continuous. 

It  has  already  been  said  that  No.  Ill  in  its  frequent  ap- 
pearances in  Middle  Pennsylvania  west  of  the  Susquehanna 
river  exhibits  nothing  like  this  thickness.  At  Orbisonia  in 
southern  Huntingdon  it  measures  only  1870  feet  (Ashburner 
F,  160).  At  Logan's  gap  in  Mifflin  county  it  measures  2304 
feet.f  In  Blair  county  gaps  the  whole  formation  was  esti- 
mated at  only  900  feet.  In  Penns  valley,  Centre  county,  it 
is  estimated  at  800  feet  or  upwards  (T4,  p.  425)  without  any 
distinction  being  made  between  Hudson  and  Utica.  In 
Friends  cove  and  along  the  Jnniata  in  Bedford  county  it 
seems  to  be  about  700  feet.:}: 

Seeing  that  the  roofing  slate  beds  are  confined  to  the  east- 
ern end  of  the  Great  Valley  in  Pennsylvania,  it  looks  as  if 
they  constituted  a  separate  formation  and  were  not  deposited 
to  the  westward;  the  thinning  of  No.  Ill  toward  middle 
Pennsylvania  being  possibly  explained  by  that  fact.  The 
belt  of  roofing  slate,  however,  runs  on  through  northern 
New  Jersey  and  southern  New  York  toward  Newburgh  on 
the  Hudson;  and  important  quarries  have  been  opened  in 
later  years  along  this  line. 

*  In  Munroe  township,  Lebanon  county,  Mr.  Sanders  got  by  construction 
6000  feet  for  the  probable  total  thickness  of  No.  III.  But  in  the  geological 
reports  rf  the  New  Jersey  Survey  an  estimated  thickness  of  only  3000  feet  is 
assigned  to  the  whole  Formation  No.  Ill  along  the  Delaware  river. 

f  Hudson  River  937,  Utica,  Upper  Gray  210,  Utica,  Middle  Black  302, 
Utica  Lower  Gray  855  feet  (F,  p.  55). 

t  Utica  being  200  feet. 


552  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

The  continuation  of  the  belt  beyond  the  Hudson  along 
the  New  York-Massachusetts  line  through  Vermont  into 
Canada,  has  given  rise  to  the  most  protracted,  the  most 
vehement,  and  undoubtedly  the  most  important  discussion 
which  has  ever  agitated  the  American  geological  world.  It 
is  called  the  discussion  of  the  TAOONIC  SYSTEM.* 


*It  commenced  upon  the  publication  in  1844  of  the  report  of  the  New  York 
geologist,  Dr.  Emmons,  upon  the  rocks  of  northern  and  eastern  New  York  '• 
and  it  has  been  participated  in  by  almost  every  geological  field  worker  in 
the  United  States,  and  by  several  of  the  most  distinguished  geologists  ot 
Europe.  It  has  not  ceased  yet ;  and  in  fact  the  controversial  literature  on 
the  subject  has  been  largely  increased  in  the  last  few  years.  The  hinge  of 
the  controversy  is  the  question  whether  the  great  slate  formation  of  the 
Taconic  mountains  in  New  York  and  of  the  plain  between  the  Green  mount- 
ains of  Vermont  and  Lake  Champlain  is  really  Formation  No.  Ill  of  Penn- 
sylvania and  the  Southern  States ;  or  whether  it  represents  the  older  and 
underlying  Cambrian  system  of  formations. 

The  place  where  the  most  perfect  cross-section  has  been  made  is  in  Georgia 
county,  Vermont,  where  broad  outcrops  of  four  formations,  two  of  slate  and 
two  of  limestone,  alternate,  and  run  side  by  side.  Some  look  upon  these 
two  slate  belts  as  repetitions  of  each  other  and  the  two  limestone  belts  as 
repetitions  of  each  other.  If  there  be  no  repetition,  we  have  at  the  bottom 
1000  feet  of  fossiliferous  limestones  ;  then  3750  feet  of  slate  (the  lowest  200 
feet,  Georgia  shales  crowded  with  fossils  and  the  uppermost  50  feet  a  quart- 
zite);  then  1700  feet  of  limestone  (many  of  the  beds  broken  into  breccia); 
then  from  3500  to  4500  feet  of  slate.  (Bulletin  U.  S.  G.  Survey  No.  30,  C.  D. 
Walcott,  1886).  If  there  be  a  repetition  we  have  a  state  of  things  greatly 
resembling  the  geology  of  Lehigh  and  Northampton  counties  in  Pennsyl- 
vania, namely,  a  limestone  formation  measuring  1000  or  2000  feet  in  thick- 
ness like  No.  II,  overlaid  by  a  slate  formation  between  3000  and  5000  feet 
thick,  No.  III.  Resemblance  is  rendered  the  more  striking  by  the  presence 
of  beds  of  roofing  slate  quarried  along  the  outcrop.  Those  who  claim  no 
repetition,  that  is,  who  refuse  to  believe  in  the  existence  of  a  fault  bringing 
up  again  the  lower  limestone  and  slate  to  the  surface  to  make  the  upper 
limestone  and  slate,  have  constructed  the  extraordinary  theory,  that  the 
upper  limestone  is  a  lenticular  or  local  deposit  in  the  body  of  the  slate  for- 
mation. A  lenticular  limestone  formation  at  least  1700  feet  thick  seems  to 
me  a  physical  impossibility  ;  and  it  is  evident  to  those  who  have  studied  the 
Appalachian  faults  that  a  great  fault  must  run  through  Georgia  county,  Vt.' 
which  swallows  up  the  upper  limestone  at  its  north  end,  and  a  large  part  of 
the  upper  slate  in  the  same  direction.  The  discussion  is,  however,  at  pres- 
ent in  the  hands  of  palaeontologists,  who  are  not  deterred  by  structural  laws 
when  these  present  extraordinary  obstacles  to  their  classification  of  the 
rocks  by  the  fossil  forms  which  they  contain. 

It  is  evident  that,  if  the  Cambrian  age  of  the  Vermont  limestone  and 
slate  be  forced  upon  us  as  it  seems  to  be ;  and  especially  if  the  two  great 
limestone  and  two  great  slate  formations  of  Georgia,  Vermont,  be  insisted 
upon,  then  it  becomes  impossible  to  explain  their  absence  in  New  Jersey 
and  Pennsylvania.  It  throws  doubt  upon  the  identification  of  the  Potsdam 


NO.  II r.       UTICA   AND   HUDSON    RIVER.  553 

As  the  slates  of  >No.  Ill  are  seen  going  down  beneath  the 
northern  edge  of  the  Mesozoic  formations  along  the  Leba- 

sandstone  along  the  foot  of  the  South  mountain  under  the  Lehigh  valley 
limestones ;  and  it  breaks  all  connection  between  the  well-established 
geology  of  the  Great  Valley  from  Alabama  to  New  York  with  its  evident 
continuation  through  Massachusetts  and  Vermont  into  Canada.  If  the 
roofing  slates  of  Georgia  county  Vt.  underlie  the  Potsdam  then  they  can- 
not be  in  the  same  formation  with  the  roofing  slates  of  No.  Ill ;  and  it  be- 
comes necessary  to  repeat  again  and  again  the  great  fact  that  at  the  bottom 
of  our  roofing  slates  of  No.  Ill  lie  the  black  Utica  beds,  and  underneath 
these  lie  the  uppermost  beds  of  No.  II  containing  Trenton  fossils. 

Tt  would  be  a  most  astonishing  thing  if  10,000  feet  of  slates  and  limestones 
in  Vermont  and  eastern  New  York  should  be  wholly  wanting  in  New 
Jersey  and  Pennsylvania  ;  and  at  the  same  time  at  least  8000  feet  of  slates 
and  limestones  on  the  Delaware  river  should  be  entirely  absent  east  of  the 
Hudson. 

It  may  be  objected,  that  the  6000  feet  of  No.  Ill  on  the  Lehigh  and  Dela- 
Avare  fades  away  to  700  or  800  feet  on  the  West  Branch  Susquehanna  and 
upper  Juniata  rivers.  But  we  must  remember  that  the  direction  of  this 
thinning  is  across  the  measures  northwestward;  and  that  the  gi  eat  thick- 
ness of  No.  Ill  reasonably  maintains  itself  along  the  line  of  strike  from 
northeast  to  southwest.  Therefore  it  is  to  be  expected  that  No.  Ill  will  be 
as  thick  in  Massachusetts  and  Vermont  as  it  is  in  the  Great  valley  of  New 
Jersey  and  Pennsylvania.  It  is  a  conclusion  of  equal  validity  that  if- No. 
Ill  diminishes  in  thickness  from  its  Great  Valley  outcrop  northwestward 
toward  the  Allegheny  mountain  it  must  have  been  of  equal  or  greater 
thickness  in  its  original  area  southeastward  toward  the  Atlantic  Ocean  ;  and 
although  the  destruction  of  this  great  formation  over  all  that  part  of  its 
original  area  has  been  almost  if  not  quite  complete,  yet  we  ought  to  find 
fragments  of  it  in  southeastern  Pennsylvania  which  have  escaped  such  des- 
truction. We  may  not  be  able  to  recognize 'it  with  absolute  certainty  in 
such  preserved  patches,  because  of  the  universal  metamorphosis  which  all 
the  rocks  of  southern  Pennsylvania  have  evidently  undergone.  In  other 
words,  if  the  limestones  of  No.  II  preserved  in  Lancaster  county,  in  tue 
Chester  county  valley,  and  in  similar  basins  still  further  and  as  far  south  as 
the  Delaware  State  line,  gradually  change  iheir  aspect  and  become  beds  of 
white  crystalline  marble,  we  ought  to  expect  that  the  slates  of  No.  Ill  if 
preserved  anywhere  south  of  the  Great  Valley  should  also  present  a  similar 
difference  of  aspect,  and  show  themselves  as  crystalline  slates  or  schists, 
perhaps  even  as  chlorite  slates,  talc  slates  or  mica  slates.  But  it  is  well 
known  that  limestones  are  always  much  more  changed  than  mud  rocks  are; 
except  when  the  mud  contains  an  unusual  percentage  of  magnesia  andiron. 
Unfortunately  too  little  attention  has  yet  been  paid  to  the  chemical  analysis 
of  the  beds  of  No.  Ill ;  and  therefore  we  are  not  in  condition  to  speculate 
safely  upon  the  degrees  and  varieties  of  crystallization  which  the  slate  beds 
of  No.  Ill  might  assume  in  the  highly  metamorphic  region  of  southeastern 
Pennsylvania.  Without  this  chemical  knowledge  we  cannot  argue  to 
conclusion  the  moot  question  whether  the  South  Valley  Hill  slate  belt  in 
Chester  and  Lancaster  counties  is  a  preserved  part  of  No.  Ill,  or  whether  it 
is  an  older  (Cambrian)  formation  brought  to  the  surface  by  a  great  fault 
running  along  the  southern  edge  of  the  Chester  county  valley. 


554  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 


,  Onddci 


LIIJ 


water  gap;  coat  dida. 


yap. 


NO.  III.       UTICA   AND    HUDSON    EIVER.  555 

nori  county  southern  line,  and  at  the  south  foot  of  the 
South  mountains  between  the  Schuylkill  and  the  Dela- 
ware ;  and  as  slates,  apparently  No.  Ill,  are  brought  up  to 
the  surface  through  the  Mesozoic  by  the  Doylestown  fault, 
we  have  a  right  to  suppose  that  the  slates  of  No.  Ill  form, 
at  least  in  some  places,  the  floor  of  the  Mesozoic  belt  along 
parts  of  its  range ;  although  there  are  good  reasons  for 
believing  that  the  principal  part  of  that  floor  consists  of  the 
eroded  outcrops  of  the  limestones  of  No.  II,  which  are  seen 
rising  from  beneath  it,  without  any  slate,  at  Norristown. 

It  is  not  surprising,  therefore,  that  Dr.  Frazer,  in  his  sur- 
vey of  Lancaster  county,  observed  at  several  places,  a  slate 
formation,  very  black  and  lustrous,  which  may  be  inferred 
to  be  Titled  slate^  because  overlying  the  limestone  forma- 
tion No.  II.  This  is  rendered  the  more  probable  when,  as 
at  Brickerville,  in  Elizabeth  twp,  the  black  slates  appear 
emerging  from  beneath  the  south  edge  of  the  Mesozoic,  as 
if  they  were  connected  underground  with  the  No.  Ill  slates 
of  Lebanon  county.  They  are  so  black  that  excavations 
have  been  made  in  them  in  the  hope  of  finding  coal ;  but 
their  principal  interest  to  the  geologist  arises  from  their  re- 
semblance to  the  Peach  Bottom  roofing  slates  which  have 
already  been  mentioned  as  crossing  the  Susquehanna  river 
at  the  Maryland  line. 

The  Peach  Bottom  roofing  slate  belt  projects  northeast- 
ward into  Lancaster  county  and  southwestward  through  the 
corner  of  York  county  into  the  State  of  Maryland.  It  ap- 
pears to  be  a  closely  folded  basin  about  9  miles  long,  the 
beds  dipping  nearly  vertical.  Eight  principal  quarries  have 
been  worked,  some  of  them  for  many  years,  to  a  maximum 
depth  of  200  feet.  As  in  the  Slatington  region,  so  here,  the 
quarries  are  not  continuous,  the  roofing  slate  quality  varying 
lengthwise  of  the  basin. 

It  is  described  in  more  detail  in  Chapter  XIII,  page  141 
above,  but  it  requires  mention  here  because  it  has  been  sup- 
])osed  to  be  a  far  south  outlier  of  III,  and  its  quarries  have 
been  compared  with  those  on  the  Lehigh,  on  the  strength 
of  numerous  undescribed  seaweed-like  fossil  markings  on 
the  faces  of  some  of  the  slates,  which  our  great  master  in 


55(5  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

Palaeontology,  James  Hall,  pronounced  to  be  possibly  a 
species  of  ButhotrepMs,  a  genus  of  Hudson  River  age.* 

This  is  a  slender  support  for  so  important  a  theory.  The 
fact  of  a  roofing  slate  foliation  of  some  of  the  beds  goes  for 
nothing;  or  rather  is  in  favor  of  a  Cambrian  age,  when  the 
great  slate  quarries  of  Wales,  and  Vermont,  and  the 
quarries  now  being  opened  in  the  South  Mountains  of  York 
and  Adams  counties  are  considered.  It  is  hard  to  imagine 
the  Peach  Bottom  slates  to  be  III,  and  the  great  limestone 
formation  II  to  be  wholly  absent  from  the  district;  and  in  its 
place  the  Chiques  quartzite  (see  page  183  above);  while  the 
surrounding  region  consists  of  mica  and  chlorite  schists. 
It  hardly  seems  worth  while  to  conjecture  that  the  Peach 
Bottom  slates  represent  the  upper  member  of  No.  Ill,  and 
the  mica  schist  country  the  lower  division  metamorphosed 
regionally.  It  is  still  less  worthy  a  conjecture  that  the 
Lehigh  slate  belt  is  a  separate  formation  deposited  where 
the  rest  of  III  and  the  whole  of  II  were  not  deposited.  In 
Pennsylvania  such  non-conformability  of  deposition  is 
scarcely  possible,  however  probable  it  may  be  elsewhere,  in 
Canada  for  instance,  f 

*Prof.  JohnS.  Stohr,  of  Franklin  and  Marshall  College,  Lancaster,  Pa., 
read  a  paper  before  the  Linmean  Society,  in  1886,  to  draw  public  attention  to 
the  Peach  Bottom  fossils.  Subsequently,  in  a  letter  to  me  dated  May  20, 
1886,  he  says  that  one  of  the  specimens  in  his  possession  "seems  to  have  a 
woody  stalk,  with  pinnae  extending  from  both  sides,  but  not  distinct  enough 
to  determine  their  character.  What  seems  to  be  pinn<e  are  probably  lobes 
or  branches  of  some  fucoid  like  Buthotrephis ;  and  what  seems  to  be  the 
stalk  or  axis  is  partly  mineral  incrustation.  When  I  first  showed  a  speci- 
men to  Prof.  Porter,  of  Lafayette  College,  he  exclaimed,  "Oh,  that  is  dendri- 
tic ;"  but  when  I  showed  him  another  lie  said,  "  No,  that  is  evidently  the  im- 
pression of  a  plant,  and  it  looks  very  much  like  a  fern."  "  So  far  as  ferns  are 
concerned  I  have  never  yet  been  able  to  convince  myself  that  any  of  the 
impressions  I  have  seen  are  really  those  of  ferns,  although  some  of  them 
strongly  resemble  ferns." 

f  Mr.  Alex.  Murray  reported  in  1879  that  in  all  places  where  fossils  could 
be  obtained  the  Hudson  river  formation  (No.  Ill)  overlaid  unconformably 
the  serpentine  beds  which  overlie  the  Levis  beds  of  the  Quebec  group,  and 
that  the  nonconformity  becomes  so  great  in  part  ot  the  islands,  that  the 
whole  Hudson  river  formation  and  all  the  Silurian  formations  are  wanting, 
and  Devonian  rocks  lie  upon  the  serpentine  beds,  which  he  suggests  may 
represent  the  (Jhazy  beds  of  No.  II.  Intrusive  masses  mark  the  break 
(Geol.  Mag.  Notice,  March,  1879,  p.  139). 


THE   THICKNESS   OF   NO.  III.  557 


CHAPTER  XLVI. 
The  thickness  of  No.  111. 

The  original  thickness  of  the  combined  Hudson  River 
and  Utica  slate  formations  in  the  region  of  the  Great  Val- 
ley cannot  now  be  measured  by  reason  of  the  excessive 
crumpling  to  which  the  whole  deposit  has  been  subjected, 
by  a  side  pressure  from  the  direction  of  the  South  mount- 
tains. 

It  is  easy  to  see  that  oceanic  deposits  of  gravel,  sand  and 
mud,  when  pressed  sideways  (by  the  shrinking  of  the  size 
of  the  globe,  or  any  other  cause),  and  lifted  thousands  of 
feet  into  the  air,  along  certain  lines,  while  in  their  wet  state, 
charged  with  ocean  water,  and  therefore  as  plastic  as  putty 
or  wax — it  is  easy  to  see  that  they  would  have  their  solid 
shapes  changed  in  various  ways. 

The  thick  deposits  of  gravel  and  coarse  sand  would  be 
folded,  but  not  crimped  ;  and  their  original  thickness  would 
be  somewhat  swollen  everywhere ;  in  some  parts  much 
more  than  in  others  ;  and  it  is  even  possible  that  where 
they  were  originally  thickest  they  would  be  artificially 
swollen  most. 

The  thinner  layers  of  liner  sand  would  be  also  folded,  but 
the  folds  would  be  smaller  and  more  numerous.  And  as 
the  finer  sand  deposits  are  always  in  company  with  mud 
deposits,  their  smaller  foldings  would  be  made  to  some 
extent  at  the  expense  of  the  mud  layers  ;  and  this  would 
save  the  sand  layers  from  being  thickened. 

The  deposits  of  fine  mud,  whether  the  common  feldspar- 
quartz  mud  of  No.  Ill,  or  the  lime-mud  of  No.  II — would 
be  crushed  out  of  all  recognizable  original  shape  ;  would  be 
swollen  in  whole  and  in  parts,  and  distorted  by  myriads  of 
folds,  crimps  or  creases  in  every  direction. 


558  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

We  have  any  number  of  illustrations  of  the  above  men- 
tioned three  modes  in  which  the  various  great  deposits  have 
actually  had  their  bulk  enlarged  and  their  shapes  distorted 
in  all  parts  of  Middle  Pennsylvania,  but  especiall}7  in  south- 
eastern Pennsylvania.  It  is  only  necessary  to  follow  the 
banks  of  the  river  channels  cut  across  the  outcropping  for- 
mations to  see  how  the  great  sandrock  and  conglomerate 
formations  No.  IV,  No.  X  and  No.  XII  are  grandly  curved — 
how  the  smaller  and  finer  sands  and  shales  of  Nos.  V, 
VII,  VIII,  IX  and  XII  are  thrown  into  series  of  smaller 
folds  —  how  the  great  soft  mud  formation  of  No.  XI  is 
closely  complicated — and  how  the  slates  and  limestones  of 
the  Great  Valley  (Nos.  Ill  and  II)  are  crumpled  and  mashed 
together  in  thousands  of  pleats,  which  crowd  each  other 
out  of  line,  so  that  in  many  of  the  outcrops  the  strata  seem 
to  run  more  across  the  vaUey  than  lengthwise  of  it.* 

Illustrations  of  this  condition  of  things  in  the  limestone 
belt  have  been  already  given  in  this  report ;  but  here  it  is 
only  needful  to  state  the  fact,  which  has  no  doubt  arrested 
the  attention  of  most  of  the  inhabitants  of  the  Valley  with- 
out their  assigning  any  geological  importance  to  it.  Geolo- 
gists however  have  observed  it  with  special  interest  be- 
cause it  is  calculated  to  raise  a  doubt  concerning  the  age 
of  the  formation,  and  its  true  relationship  to  the  overlying 
formations,  because  it  creates  the  impression  that  the  lime- 
stone formation  was  crumpled  and  uplifted  from  the  ocean 
and  worn  away  to  a  level  surface,  and  submerged  again,  to 
be  covered  by  the  slate  formation.  In  other  words,  geolo- 
gists have  found  it  hard  to  harmonize  the  irregular  detailed 
stratification  of  the  limestone  with  the  conformity  of  the 
whole  underlying  limestone  formation  to  the  whole  over- 
lying slate  formation. 

And  the  same  apparent  difficulty  is  reported  in  the  case 
of  the  irregular  local  dips  and  strikes  of  the  slate  belts, 
especially  along  the  northern  or  upper  edge  of  the  belt, 

*See  the  illustrations  of  folded  beds  in  the  slate  quarries  in  Report  D3. 
See  especially  Fig.  II,  page  119,  D3,  whtsre  a  bed  of  slate  is  thickened  in  the 
fold.  See  also  the  numerous  sections  of  thickened  folds  in  the  Anthracite 
Reports  A  A. 


THE   THICKNESS   OF   NO.  III.  559 

where  the  top  slate  strata  are  overlaid  by  the  very  regular 
sandstone  formation  of  the  North  mountain.  This  has 
bred  a  suspicion  that  the  two  formations  (III  and  IV)  are 
UJiconfoj  mcible — did  not  follow  each  other  immediately  in 
time — but  that  the  slate  formation  was  elevated  and  eroded 
and  resubmerged  to  receive  the  long  subsequent  sand  de- 
posits. 

But  let  it  be  once  understood  that  if  a  very  thick  fine 
shaly,  slaty  or  muddy  formation  lies. between  two  very 
massive,  coarse,  sandy  or  gravelly  formations,  and  all  three 
are  subjected  to  a  great  side  pressure,  the  sands  will  be 
merely  thrown  into  great  waves,  but  the  mud  will  be  badly 
crumpled  together  in  thousands  of  closely  compressed  small 
local  folds — the  idea  of  non-con  for  inability  at  the  contact 
of  the  limestone  and  slate  belts  of  the  Valley,  and  at  the 
contact  of  the  slate  belt  and  the  North  mountain  sandstone, 
will  no  longer  impose  upon  the  imagination.* 


The  thickness  of  Formation  No.  III. 

To  return  then  to  the  starting  point  of  this  chapter,  it  is 
quite  impossible  to  measure  the  thickness  of  the  slate  for- 
mation No.  Ill  along  the  Great  Valley  on  account  of  irs 
closely  folded,  swollen  and  distorted  condition.  All  that 
we  can  say  is,  that  in  Middle  Pennsylvania,  where  it  is  not 
in  that  condition,  where  it  is  merely  upturned,  it  has  been 
measured  pretty  accurately ;  and  while  it  is  in  some  places 
only  1000,  in  other  places  it  is  1600  feet ;  being  thinner 
towards  the  Allegheny  mountain  and  thicker  towards  the 
South  Mountan.*  How  much  of  this  difference  is  due  to  the 
original  thinning  of  the  deposit  northward,  and  how  much 
of  it  is  to  be  set  down  to  the  diminished  intensity  of  the  side 
pressure  as  we  recede  from  the  South  mountain  range,  can- 
not be  known. 

That  it  increases  in  thickness  eastward  is  indicated  by 
the  fact  that  the  measurable  thickness  increased  from  700'? 

*For  further  remarks  upon  this  subject  see  foregoing  chapters  on  the  lime- 
stone belt,  and  a  following  chapter  on  the  non-conformity  of  IV  upon  III. 


560  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

at  Bedford*  (Stevenson),  and  900'  ?  at  Tyrone  city  (Platt  and 
Sanders),  to  1000'  at  Belief onte  (H.  D.  Rogers),  f  and  1600' 
at  Logan  Gap  (H.  D.  Rogers).:}: 

As  Prof.  Stevenson  says  that  it  is  decidedly  thicker  at 
McConnellsburg  than  at  Bedford,  and  as  Messrs.  Aslibnrner 
and  Billingot  a  measurement  of  1870'  at  Orbisonia,  we  must 
suppose  it  to  increase  also  in  a  southerly  direction.  Taken 
together  these  data  lead  us  to  expect  a  great  thickness  in  the 
Chambersburg  valley  ;  and  an  increasing  thickness  from 
Chambersburg  towards  Harrisburg,  Reading  and  Easton. 

It  is  not  so  astonishing  then  as  it  otherwise  would  be  that 
both  Mr.  Sanders  and  Dr.  Chance  gives  it  a  thickness  of 
6000'  at  the  Schuylkill,  Lehigh  and  Delaware  water  gaps.§ 

*  In  Bedford  county  Prof.  Stevenson  estimates  the  total  thickness  of  both 
Ilia  and  III6  at  700' ;  for  an  outcrop  1040'  wide  with  dips  ot  30°  to  60°  follows 
Tussey  mountain  across  the  Juniata  below  Bedford  ;  and  the  same  estimate 
is  made  along  Evitt's  mountain  on  the  west  side  of  Friend's  cave.  But  in 
Fulton  county,  around  the  edge  of  the  McConnellsburg  cove,  he  says,  the 
thickness  is  evidently  greater.  The  Utica  (Ilia)  on  the  Bedford  pike  near 
Williams  Grove  is  about  200'.  (T2,  p.  93). 

t  Mr.  D'Invilliers  calls  it  at  Bellefonte  1011',  in  Report  T4,  p.  304. 

\  Billin  and  Ashburner's  measurement  make  it  here  1632'. 

§  Prof.  Cook  says  that  in  New  Jersey  it  cannot  be  accurately  measured, 
bxit  calculates  from  steep  N.  W.  dips  across  a  2  mile  belt  from  the  Delaware 
water  gap  south  to  Columbia  it  is  probably  3000'.  But  2  miles  at  only  15° 
would  make  3000',  and  the  dips  are  much  steeper  than  that;  see  sections  in 
Reports  G6,  and  D3. 

The  latest  precise  thickness  of  the  formation  was  got  (in  1886)  by  my 
lamented  assistant,  Mr.  C.  E.  Ashburner,  from  a  study  of  the  Knowersville 
gas  well  in  Albany  county,  N.  Y.,  25  miles  west  of  Albany.  It  struck  the 
top  of  the  Trenton  limestone  (II)  at  2880',  and  went  112  into  that  formation  ; 
mouth  of  well  about  500'  above  tide;  top  of  Hudson  river  slate  (III)  550' 
above  well  mouth  ;  therefore  total  thickness  of  111,3430'. — The  lower  part 
of  the  formation  is  calcareous.  Specimens  from  2500'  downward  were 
analysed  and  yielded  25  per  cent  of  carbonates,  lower  down  10  per  cent ; 
at  the  top  of  the  Trenton  the  percentage  suddenly  rose  to  60  per  cent  and 
soon  to  80  per  cent;  continuing  at  that  to  the  bottom  of  the  boring.— The 
dark  Utica  formation  (Ilia)  was  plainly  distinguishable,  lying  on  the 
Trenton,  and  calcareous,  as  stated  above. — The  bottom  of  the  Lower  Helder- 
berg  limestone  (VI)  rests  directly  upon  the  top  of  the  Hudson  river  states 
(III6)  Clinton  and  Medina  (V,  IV)  being  entirely  absent  in  this  part  of 
New  York.  The  Cauda-Galli  (VII&)  makes  a  bold  cap  tQ  the  mountain, 
and  is  probably  the  cause  of  the  cliff  which  runs  along  the  escarpment  for 
many  miles  westward  towards  Utica. 

The  Clyde  well  in  Wayne  county,  central  New  York,  is  said  by  Prof.  C.  S. 
Prosser  of  Cornell  University  to  have  gone  through  Oswego  sandstone,  210'  ; 
shale  and  sandstone,  170'  ;  Hudson  river  and  Utica  650'  ;  total  1030',  to  top 
of  Trenton  limestone.  (American  Geologist,  Oct.  1890,  page  204.) 


THE   THICKNESS   OF   NO.  III.  561 

Whether  the  formation  be  3000'  or  6000'  thick  along  the 
Susquehanna  above  Harrisburg  cannot  be  discovered;  but 
that  it  is  several  thousand  feet  thick  is  certain,  from  the 
fact  that,  although  the  belt  is  about  4  miles  wide,  occupy- 
ing the  river  banks  all  the  way  from  the  upper  part  of  the 
city  to  the  Penn.  RR.  bridge  in  the  gap,  yet  the  under- 
lying limestone  formation  is  never  once  brought  to  the  sur- 
face by  any  of  the  folds. 

And  this  is  the  case  eastward  through  Dauphin  county, 
and  westward  through  Cumberland  county.  Not  until  we 
go  six  miles  into  Franklin  county,  to  within  2  miles  of 
Strasburg,  does  the  underlying  limestone  begin  to  appear 
on  the  sharp  top  of  the  Strasburg  anticlinal,  which  keeps  it 
at  the  surface  from  here  on  into  Maryland. 

The  point  near  Strasburg  where  the  limestone  appears  is 
about  a  mile  from  the  crest  of  the  North  Mountain.  Two 
separate  exposures  of  slate  a  mile  southwest  of  Strasburg 
show  each  a  dip  of  60°;  and  this  maybe  taken  as  the  dip  of 
the  whole  formation  from  Strasburg  to  the  mountain;  which 
would  give  it  a  total  thickness  of  something  over  4000'. 

Proceeding  further  west  to  the  Bedford  pike  at  Mercers- 
burg,  the  slate  belt  is  there  only  about  a  third  of  a  mile 
wide,  which,  on  a  dip  of  70°  (in  the  limestone),  would  re- 
duce the  thickness  to  1500';  but  there  is  some  reason  to 
think  that  part  of  the  slate  formation  is  here  overlapped  by 
a  fault  at  the  contact  of  the  limestone. 


36 


562  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 


CHAPTER  XLVII. 
Character  of  Formation  No.  III. 

The  slate  formation  consists  of  dark  mud-rocks  (slate) 
more  or  less  sandy;  many  interpolated  layers  of  fine  sand- 
stone; a  few  layers  of  poor  limestone,  or  limy  mudstone, 
not  to  be  compared  in  quality  with  the  limestone  beds  of 
the  southern  side  of  the  valley;  and  here  and  there,  at  dis- 
tant points  in  the  length  of  the  valley,  beds  of  sandstone  so 
coarse  as  to  deserve  the  name  of  conglomerate. 

The  slates  are  softer  and  darker  in  the  lower  part  of  the 
formation;  and  are  sometimes  quite  black  at  the  very  bot- 
tom of  the  formation,  just  over  the  limestone  No.  II.* 

They  are  harder  and  more  sandy  (and  the  beds  thicker 
and  more  massive)  towards  the  upper  part  of  the  formation; 
and  here  we  find  most  of  the  sandstones,  some  of  which  can 
furnish  good  flag-stones,  and  are  in  fact  quarried  in  Berks 
county. 

These  sandstone  beds  are  mostly  grey,  sometimes  olive, 
sometimes  greenish  in  hue.  The  intervening  slates  are 
mostly  dark  grey,  sometimes  olive  or  greenish  and  some- 
times a  pronounced  red.  These  colors  are  given  to  the 
rocks  by  small  percentages  of  carbonate  and  oxide  of  iron 
distributed  through  the  mass ;  but  nowhere  concentrated 
into  iron  ore  beds. 

It  is  remarkable  that  the  red  color  is  not  noticeable  along 
the  Great  Valley  in  New  York,  New  Jersey, f  and  eastern 
Pennsylvania  until  one  approaches  the  Schuylkill  river. 
As  soon  as  Berks  county  is  entered  outcrops  of  red  slate 

*  This  is  the  Utica  slate  formation  of  the  New  York  geologists.  The  main 
bulk  of  No.  Ill  is  understood  to  be  the  Hudson  River  formation. 

t  Prof.  Cook  speaks  in  one  place  of  slates  exposed  in  a  railway  cut  being 
reddish-yellow,  fragile  and  earthy,  contrasting  strongly  with  the  dark  blue- 
black  solid  roofing-slate  variety.  Geol.  N.  J.,  1868,  p.  138. 


CHARACTER   OF   FORMATION   NO.  III.  563 

become  numerous  ;  increase  in  number  through  Lebanon 
county;  and  can  be  seen  traversing  Dauphin,  Cumberland 
and  Franklin  into  Maryland.  In  Virginia  and  Tennessee 
the  whole  formation  gradually  takes  on  a  reddish  color,  and 
is  quite  red  in  many  places.* 

The  place  of  the  red  slate  belt  in  the  formation  is  a  matter 
of  some  moment  and  will  be  discussed  after  and  in  connec 
tion  with  a  description  of  the  roofing  slate  belt  further  on. 

It  is  possible  that  the  red  color  is  one  of  the  consequences 
of  the  decomposition  of  iron  pyrites  finely  disseminated 
through  the  original  mud,  because  iron  pyrites  itself  is  one 
of  the  commonest  ingredients  of  the  slate  formation  as  a 
whole,  and  is  abundant  enough  at  some  of  the  slate  quar- 
ries to  oblige  their  owners  to  reject  the  beds  which  are  most 
infested  with  it.  Several  instances  are  mentioned  by  Mr. 
Sanders  in  report  D3.  Prof.  Cook  speaks  of  several  local- 
ities where  pyrites  is  disseminated  through  the  rock  mass. 

But  it  is  much  more  likely  that  the  red  slate  beds  were 
originally  deposited  as  red  clay,  and  that  the  presence  of 
pyrites  is  merely  a  coincidence  ;  for  pyrites  is  perhaps  more 
abundant  in  the  roofing-slate  part  of  the  valley  east  of 
where  the  red  rocks  begin  to  make  a  show ;  and  moreover, 
the  sulphur  of  the  pyrites  unites  with  the  alumina  of  the 
slate  rock  to  produce  the  white  efflorescence  which  is  so 
often  to  be  seen,  while  the  iron  set  free  is  carried  off  by  the 
waters.  At  all  events  there  is  no  apparent  precipitation  of 
limonite.f 

The  amount  of  iron  in  the  rooks  of  the  slate  belt  must 

*  This  is  very  surprising  to  a  geologist  fresh  from  Pennsylvania,  accustomed 
as  he  is  to  see  the  red  formation  always  lying  back  of  the  mountain  and  not 
in  front  of  it ;  and  the  change  in  III  from  gray  to  red  going  south  is  still 
further  accentuated  by  a  corresponding  change  in  V  from  red  to  gray. 

|To  show  that  the  amount  of  iron  in  slates  and  shales  is  not  necessarily 
influential  in  reddening  them  it  is  only  needful  to  compare  the  following 
analysis  by  Mr.  McCreath  : 

1.  Yellowish  white  damourite  slate  of  Lehigh  county,  from  the  bottom  of 
No.  II,  two  specimens.     (Report  M,page  92.) 

2.  Red  shale  from  the  Catskill  No.  IX  of  Tioga  county.     (Report  MM, 
page  372.) 

3.  Catskill  red  shale  from  Wayne  county.     (  M3,  page  108. ) 


564 


GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 


vary  within  a  small  and  narrow  range.     Prof.  Cook  gives 
the  following  analysis : 

A.  Ordinary  bluish  black  Delaware  Gap  roofing  slate. 

B.  Sandy  massive  Deckertown-pike  slate. 


Silica, 

Alumina 

Protoxide  of  iron,  . 

Lime, 

Magnesia,   ... 

Potash, 

Soda 

Carbonic  acid,     .   . 
Carbon  [graphite?], 

Sulphur, 

Water,     


A. 

56.60 
21.00 
5.65 
3.42 
2.30 
1.10 
0.50 
2.20 
2.69 
0.57 
'3.00 


77.60 


7.32 


B. 

68.00>82  4Q 
14.40> 

5.40 

2.68] 

!:Sh 

O.llj 
2.30 


2.70 
99.10 

The  pyrites  (sulphide  of  iron)  so  universally  disseminated 
through  the  slate  formation  must  have  been  one  of  the 
original  constituents  of  the  oceanic  mud  ;  for  there  are  no 
traces  anywhere  to  be  found  of  either  ancient  or  modern 
volcanic  action  in  the  Great  Valley,  to  supply  sulphur.* 
The  amount  of  sulphur  also,  in  any  specimen  of  slate  is  so 
small  that  we  must  suppose  it  derived  from  the  sea  water 


Silica,                     .... 

55.880 

1. 
60.530 

2.                  3. 
59.630        59.260 

Alumina,    
Oxide  of  iron,  
Lime,   
Magnesia,  
Water,     
Alkalies,            

19.400 
10.570 
.080 
1.710 
8.170 
3.760 

17.400 
9.290 
.080 
1.920 
5.510 
5.270 

18.560        19.877 
.8.571(a)  10.071(6) 
.672            .250 
2.252          1.917 
4.560          3.600 
5.109          4.855 

Sesquiox.  manganese,  . 
Sulphuric  acid,    .... 
Phosphoric  acid,  .... 

.290            — 
.123            .012 
.279            .058 

99.570        100.000        100.046 

(a)  and  (6)  are  sesquioxide  of  iron. 

Dr.  Genth's  analysis  of  the  blackish  Peach  Bottom  roofing  slate,  the  red 
dish  white  and  the  greyish  white  damourite  slates  of  Lehigh  county  (Re- 
port B,  page  126)  show  that  the  green  specimens  had  more  iron  than  the 
reddish. 

*  The  two  trap  dykes  which  cross  the  valley,  one  in  Cumberland  county 
and  one  in  Berks  county,  are  of  so  local  a  character  that  they  need  not  be 
considered. 


CHARACTER    OF    FORMATION    NO.   III.  565 

above,  rather  than  from  the  earth-crust  beneath  the  oceanic 
mud.  But  if  it  came  from  the  sea  waters  it  must  be  as- 
cribed to  sea  vegetation  ;  about  which  however  we  know 
very  little,  because  the  marks  which  that  vegetation  has 
left  on  the  slate  rocks  are  few  and  indistinct,  especially  so 
along  the  slate  belt  of  the  Great  Valley.  In  New  York 
state  however  great  numbers  of  what  seem  to  be  sea-weed 
forms  are  found  in  the  Hudson  river  slate  formation  No. 
III.  At  all  events,  we  know  that  the  ocean  waters  in  that 
age  swarmed  with  innumerable  living  things  called  grap- 
tolites  ;  and  if  these  were  more  animal  than  vegetable,  still 
it  is  not  to  be  supposed  that  the  waters  were  not  quite  as 
prolific  of  other  kinds  of  more  strictly  vegetable  life,  and 
in  sufficient  quantity  to  furnish  all  the  sulphur  required  to 
explain  the  analyses.  Much  of  this  vegetation  was  prob- 
ably of  microscopic  size  and  infinite  fecundity.  We  can- 
not otherwise  account  for  the  sustenance  of  the  innumer- 
able swarms  of  animals  which  then  populated  the  sea;  es- 
pecially the  free-swimming  trilobites^  6f  all  sizes  from  an 
inch  to  a  foot  in  length.  But  besides  trilobites  there  was 
the  greatest  abundance  of  other  kinds  of  animals — chain 
corals,  star  fish,  shell  fish  of  many  kinds  as  well  as  flesh- 
eating  cuttle  fish  * — in  other  regions  of  the  ocean,  if  not  in 
the  part  of  it  which  is  now  Pennsylvania.  And  a  few  frag- 
ments of  land  plants  have  been  found,  which  compels  us  to 
believe  that  rivers  brought  plenty  of  decayed  vegetation  into 
ths  sea,  and  therefore  a  percentage  of  sulphur.  And  of 
course  the  same  rivers  must  have  brought  down  to  the  sea 
the  mud  out  of  which  our  great  slate  formation  was  made. 
The  continent  must  have  been  large  from  which  so  much 
mud  was  manufactured  ;  and  the  rivers  must  have  been 
huge  which  brought  so  much  stuff  to  the  sea.  Its  fineness 
shows  that  the  mouths  of  these  rivers  were  at  a  great  dis- 
tance ;  and  probably  there  were  vast  deltas,  mud-flats.  If 
so,  it  is  impossible  not  to  imagine  them  covered  with  some 
sort  of  salt  water  vegetation,  and  that  will  help  to  account 
for  the  abundance  of  such  shell  fish  as  liked  the  shallows. 

*  A  rather  dangerous  term  for  popularizing  the  designation  Cephalopod ; 
but  one  can  do  no  better. 


566  GEOLOGICAL   SURVEY    OF   PENNSYLVANIA. 

That  the  deltas  and  shallows  must  have  been  at  a  great  dis- 
tance from  the  present  site  of  our  Great  Valley  is  evident ; 
for  it  is  impossible  to  suppose  5000  or  6000  feet  of  mud  to 
have  been  deposited  in  any  but  a  deep  sea  basin  ;  for  if  the 
shores  had  been  near,  some  of  the  earlier  and  middle  beds 
would  have  been  of  coarse  sand  and  gravel  ;  but  none  such 
were  deposited  until  the  basin  had  become  well  filled  and 
the  shores  approached  nearer  by  some  change  of  the  world's 
ocean  level ;  then  indeed,  the  upper  flagstones  of  No.  Ill 
were  deposited  over  the  older  fine  muds ;  and  finally  the 
off-shore  shingle  of  No.  IV  (Oneida  conglomerate  and 
Medina  sandstone)  was  spread  overall. 

These  considerations  are  offered  here  not  for  the  purpose 
of  settling  scientific  questions  still  under  discussion  among 
geologists  ;  but  to  familiarize  the  minds  of  readers  of  this 
report  with  the  extent  and  complexity  of  our  geological 
phenomena  ;  and  to  illustrate  the  value  of  the  practical  rule 
to  keep  all  the  facts  in  view  for  explaining  each  one. 

Quartz  veins  are  very  numerous  in  many  parts  of  the 
slate  belt.  They  are  seldom  more  than  an  inch  or  so  thick 
and  usually  cut  across  the  beds,  but  often  insert  themselves 
between  the  slates. 

The  substance  matter  of  these  veins,  which  is  now  so 
glassy  and  brittle,  was  originally  fluid,  and  deposited  itself 
in  any  open  crack  or  fissure  in  the  rocks,  however  small. 
This  fact  was  practically  discovered  by  Dr.  Graham  of  Lon- 
don about  20  years  ago,  when  he  succeeded  in  separating 
silica  in  a  jelly-like  state  from  other  elements  with  which 
it  is  commonly  combined  as  a  hard  rock.  Graham's  gel- 
atinous silica  (or fluid  quartz)  can  now  be  made  by  any 
chemist  and  kept  in  bottles  for  a  long  time  before  it  will 
harden  into  quartz.  Nature  has  been  manufacturing  it  in 
all  ages  and  in  immense  quantities,  and  has  put  it  to  sev- 
eral particular  uses,  one  of  which  is  to  make  gems  like  the 
precious  opal,  etc.;*  but  chiefly  to  heal  the  wounds  of  the 

*A  beautiful  example  of  the  use  which  Nature  makes  of  gelatinous  silica 
is  the  production  of  a  kind  of  opal  above  a  bamboo  joint  These  lens-shaped 
stones,  called  tabasheer,  are  sold  for  "madstones"  or  "snakestones"  in 
India.  See  G.  F.  Kunz's  paper  on  "  Madstones  and  their  Magic  "  in  Science, 
Vol.  XVIII,  No.  459,  Nov.  20,  1891,  page  286. 


CHARACTER   OF    FORMATION"   NO.  III.  567 

rock  formations  after  earthquakes,  to  fill  up  all  the  cracks 
opened  in  the  strata  (when  compressed  and  folded  and 
foliated  like  those  of  the  slate  belt)  with  vein  quartz. 

The  material  out  of  which  nature  manufactured  the  fluid 
quartz  is  indicated  by  the  analyses  on  page  564  above. 

The  specimen  of  Delaware  gap  roofing  slate  (A),  when 
analyzed,  was  found  to  be  more  than  one-half  silica.  The 
other  specimen  (B)  was  about  two-thirds  silica.  In  fact, 
taking  the  whole  slate  belt  of  the  great  valley  together,  if 
we  could  analyze  it  as  a  single  specimen,  we  should  proba- 
bly get  from  it  about  60  PER  CENT  of  silica,  20  PER  CENT 
of  alumina  and  the  remaining  10  PER  CENT  would  be  lime, 
magnesia,  soda,  potash,  iron,  carbon,  sulphur,  oxygen,  hy- 
drogen, with  traces  of  other  rarer  elements. 

Thus  we  see  that  the  original  mud  deposit  was  mainly 
silicate  of  alumina  derived  from  the  wear  and  tear  of  feld- 
spar rocks  on  some  distant  continent.  But  a  certain  extra 
amount  of  silica  came  from  the  wear  and  tear  of  silicate 
rocks  not  feldspar  ;  and  this  extra  amount  was  an  availa- 
ble reserve  for  the  natural  manufacture  of  vein  quartz  after 
a  long  lapse  of  time.*  For  the  veins  had  to  be  opened  be- 
fore they  could  be  filled.  The  original  mud  had  no  fissures 
in  it.  When  the  bed  of  the  sea  was  lifted  into  the  air, 
dried,  hardened,  folded  and  fissured,  the  deposit  of  vein 
quartz  took  place.  The  whole  mass  was  still  warm  as  well 
as  wet,  not  merely  warm  but  hot,+  and  must  have  remained 
so  for  an  indefinite  number  of  ages  since  the  cooling  could 
take  place  only  at  the  surface  of  the  whole  mass,  now 
elevated  30,000  feet  above  its  former  level.  The  sea  water 
still  resident  throughout  the  mass  shared  the  high  temper- 
ature of  the  mud  deposits,  dissolved  a  portion  of  their 
silica,  and  filled  the  cracks  with  vein  quartz. 

*  Of  course  the  above  statement  is  too  short  and  simple  to  be  in  any  sense 
complete.  Chemists  and  geologists  will  fill  it  out  for  themselves.  But 
some  true  and  easily-seized  notion  of  the  genesis  of  quartz  veins  ought  to 
be  given  to  the  uninitiated. 

f  The  law  of  increase  of  heat  downwards  from  the  surface,  at  the  rate  of  1° 
F.  per  60'  depth  (added  to  the  local  invariable  annual  mean  temperature 
ten  feet  beneath  the  surface)  would  give  the  rocks  of  No.  Ill  before  eleva- 
tion a  temperature  of  melting  lead,  635°  F. 


568  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

This  operation,  taking  place  throughout  the  whole  3000 
feet  of  uplifted  deposits,  would  have  different  results  in  the 
different  formations.  In  the  sand  and  gravel  deposits 
(Potsdam,  Medina,  Oneida,  Oriskany,  Pocono,  Pottsville) 
the  silica  would  be  deposited  between  the  grains  and  pebbles, 
cementing  them  into  a  solid  sheet  or  stratum  of  quartzite, 
sandrock,  or  conglomerate.*  The  mud  deposits  would  not 
only  be  cemented,  but  cut  with  transverse  and  longitudinal 
quartz  veins.  The  lime  muds  would  receive  quartz  veins  in 
abundance  (as  we  see  in  the  present  surface  sections),  but 
an  infinitely  greater  number  of  calcite  veins — the  supply 
of  silica  being  limited,  and  the  supply  of  carbonate  of  lime 
unlimited. 

Meanwhile  the  tearing  down  of  the  elevated  mass  in  the 
regions  of  eternal  frost  went  on,  and  formation  after  forma- 
tion was  washed  away,  continually  producing  a  lower  and 
lower  upper  surface,  until  the  present  surface  level  has  been 
reached;  and  still  the  waste  goes  on,  and  still  the  surface 
gets  nearer  and  nearer  to  sea  level. 

The  quartz  veins  of  the  swept  away  upper  portions  of  the 
mass,  have  been  carried  off  with  the  rest,  into  the  Atlantic. 
But  the  tops  of  the  quartz  veins  which  are  at  the  present  sur- 
face strew  the  ground  with  fragments  underneath  where  they 
once  existed  as  solid  veins.  This  accounts  for  the  quanti- 
ties of  quartz  fragments  which  are  found  lying  on  the  pres- 
ent surface  in  many  places  along  the  slate  belt.  For  ex- 
ample, on  the  Jordan  in  Low  Hill  township  Lehigh  county 
the  ground  is  covered  with  pieces  of  quartz  (See  D3,  p.  124, 
No.  187).  A  few  miles  south  of  this  the  veins  of  quartz 
show  in  the  slates  (No.  190,  p.  124).  In  most  of  the  slate  of 
that  region,  quartz  veins  are  abundantly  numerous,  and 
some  of  them  are  quite  large,  like  the  one  noted  in  D3,  page 
105,  No.  96,  at  the  Northampton  Slate  Quarry.  The  inser- 
tion of  the  quartz  between  the  laminae  of  a  slate  beds,  that 
is,  following  its  lines  of  cleavage,  is  noted  in  D3,  p.  122, 
No.  175,  at  the  North  Peach  Bottom  Company's  quarry. 

*  This  is  a  fair  way  of  accounting  for  the  general  quartzite  aspect  of  the 
lowest,  hottest  and  most  compressed  formation  No.  I,  as  compared  with  the 
higher,  cooler  and  less  compressed  coarse  strata  of  the  Coal  measures,  No. 
XIII. 


CHARACTER   OF    FORMATION   NO.  III.  569 

Flag  stone  layers  occur  in  the  Slate  formation  No.  Ill, 
and  many  small  quarries  have  been  opened  along  the  slate 
belt  both  in  New  Jersey  and  Pennsylvania;  some  of  them 
in  connection  with  the  roofing  slate  quarries  (to  be  described 
farther  on) — some  of  them  having  apparently  nothing  to  do 
with  the  roofing  slate  strata. 

The  sand  deposits  which  made  these  flagstone  layers,  were 
in  some  few  places  so  coarse  as  to  deserve  the  name  of  gravel 
beds,  or  conglomerate  rocks,  although  the  pebbles  in  them 
are  all  small.  For  instance,  there  is  a  pretty  high  ridge 
of  land  two  miles  long  south  of  Slatington  in  Lehigh  county, 
made  rocky  by  loose  fragments  of  a  conglomerate.*  But 
where  the  rocks  are  exposed  on  the  Lehigh  river,  they  con- 
sist of  fine-grained  sandstone,  in  a  series  of  beds,  none  of 
them  more  than  four  feet  thick,  40  feet  of  them  being  visi- 
ble and  the  rest  concealed  (See  D3,  p.  114,  No.  142). 

As  a  rule  the  sandstone  beds  in  the  slate  belt  are  fine- 
grained and  thin-bedded.  That  they  are  very  numerous, 
and  are  separated  by  slate  beds  can  be  seen  wherever  the 
belt  is  not  too  much  folded.  A  very  good  exhibition  the 
purpose  is  made  in  Berks  county,  Albany  township,  where 
the  rocks  are  vertical.  Here  500  feet  of  fine  sandstones  and 
dark  gray  slates  can  be  measured  (see  D3,  p.  126). f 

Sometimes  both  the  sandstone  and  the  slate  beds  all  have 
a  greenish  hue.  Such  a  belt  crosses  the  Schuylkill  river 
at  Hamburg  (D3,  p.  128  to  133)4  Sometimes  the  slates 
are  olive  colored  or  red,  as  already  mentioned.  Red  slates 
at  various  places  along  the  Hamburg  belt  strike  so  as  to 
come  between  the  sandstone  outcrops.  ||  The  flagstone 
strata  quarried  in  the  northeast  corner  of  Perry  township, 
Berks  county,  roll  so  as  to  connect  them  with  the  red  slate 
exposures  (No.  244).  On  the  other  hand  the  quarries  about 

*  Dr.  T.  Sterry  Hunt  was  so  much  impressed  by  this  exhibition  of  coarse 
and  massive  strata  in  the  midst  of  the  slate  belt,  as  to  imagine  it  a  proof  of 
the  far  greater  age  of  the  formation,  oil  grounds  which  it  is  not  necessary 
here  to  discuss. 

t  See  also  p.  113,  No.  133,  on  the  Lehigh  ;  also,  the  Emanuel  Church  hill 
in  Northampton  county  covered  with  thin  sandstones,  p.  105  D3. 

JSee  also  north  of  Seeberlingville,  page  126,  No.  198. 

||  No.  236. 


570  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

Shoemakersville  do  not  seem  to  have  a  connection  with  the 
red  slate  belt  (No.  250,  251). 

It  looks  as  if  the  upper  part  of  the  slate  formation  No- 
Ill  furnishes  most  of  the  flaggy  sandstone  strata.  There 
are  quarries  in  Berks  county  where  the  strata  dip  65°  to- 
wards the  south,  in  a  line  which  would  carry  them  west 
into  the  spur  of  the  North  mountain.  It  is  hardly  possible 
therefore  to  assign  them  a  position  more  than  1000  feet  or 
so  below  the  top  of  No.  III.  The  flags  taken  out  here  (at 
J.  Gilt's,  D3,  No.  205)  have  rough  faces,  but  dress  up  well. 

It  is  not  safe  to  conclude  however  that  the  flagstone 
strata  are  confined  to  the  upper  part  of  the  formation.  They 
may  probably  be  found  in  all  parts  of  it.  The  massive 
flaggy  sandstone  outcrops  south  of  Smiths ville  in  Berks 
county  are  in  the  line  of  the  red  slate  belt ;  and  yet  there 
are  argillaceous  limestone  beds  near  them  (No.  222,  223). 


The  mineralogical  poverty  of  No.  III. 

The  mineral  wealth  of  the  Great  Valley  is  concentrated  in 
its  southern  or  limestone  belt.  The  northern  or  slate  belt 
is  a  farming  district,  of  a  fertility  varying  with  the  more 
or  less  sandy  quality  of  the  different  layers  of  slate  which 
come  to  the  surface  along  narrow  lines  parallel  to  the  sides 
of  the  valley. 

As  the  slate  formation  is  several  thousand  feet  thick 
everywhere  along  the  Great  Valley  ;  it  might  be  expected 
that  at  least  some  of  this  huge  series  of  layers  would  be 
valuable  to  the  mining  interests  of  the  country.  Not  so, 
however.  A  few  thin  layers  of  poor  limestone,  or  limy 
slate  alone  appear  to  attract  attention.  Not  a  single  min- 
eral ore  is  to  be  found  in  the  whole  extent  of  slate  belt  of 
the  valley.  Not  even  a  bed  of  iron  ore  of  any  kind  what- 
ever worth  shafting  on  has  ever  been  seen  or  is  likely  to 
be  ever  seen.  The  whole  formation  seems  to  have  been  de- 
posited in  deep  oceanic  waters,  and  what  metallic  salts  were 
deposited  with  the  mud  and  fine  sand  remain  disseminated 
through  the  whole  so  as  to  be  practically  worthless  in  a 
strictly  mineral  sense. 


CIIVKACTKK    OF    FORMATION    NO.   III.  i)71 

Neither  Oil  nor  Gas  in  No.  HI. 

Of  late  it  has  become  necessary  to  give  warning  that 
neither  oil  nor  gas  is  to  be  found  by  any  amount  of  boring 
anywhere  in  the  Great  Valley. 

Since  the  wonderful  development  of  gas  and  oil  at  Lima 
and  other  towns  of  Western  Ohio  and  Indiana  from  the 
Trenton  limestone  a  thousand  projects  have  been  formed 
to  exploit  the  Trenton  in  Middle  Pennsylvania  by  boring 
down  to  it  through  the  overlying  slates.  Some  of  these 
vain  projects  have  disregarded  the  commonest  rules  of  pros- 
pecting. For  example,  a  well  was  bored  north  of  Harris- 
burg  where  the  slates  stand  vertical !  No  attention  was  paid 
to  the  fact  that  the  bore  hole  if  vertical  itself  must  neces- 
sarily keep  down  always  in  the  same  rocks  in  which  it 
started,  at  least  until  they  turned  to  take  a  north  dip.  It 
would  probably  require  a  depth  of  between  10,000  and 
20,000  feet  for  that  well  to  strike  the  Trenton  limestone 
which  crops  out  at  Harrisburg  ;  where  moreover  it  raises 
no  suspicion  of  oil  or  gas. 

A  little  science  is  a  dangerous  thing.  It  usually  resides 
in  words  and  names.  The  Trenton  limestone  has  yielded 
vast  quantities  of  gas  and  some  oil  in  Ohio  and  Indiana; 
why  not  in  Pennsylvania?  Simply  because  the  Trenton  in 
Ohio  and  Indiana  lies  on  almost  a  dead  level,  and  far  enough 
under  ground  (1000-2000  feet)  to  preserve  its  gas  from  es- 
caping until  bore-holes  are  provided.  In  the  Great  Valley, 
on  the  contrary,  as  every  farmer  must  know  who  opens  a 
quarry  on  his  farm,  the  limestone  beds  have  been  upturned, 
even  overthrown,  crushed,  crumpled  and  broken  into  frag- 
ments, and  in  that  condition  they  reach  the  surface.  Why 
is  the  limestone  belt  scarce  of  water?  Because  the  up- 
turned and  broken  beds  easily  permit  the  rainwater  to  de- 
scend to  caverns  which  ramify  beneath  the  valley  in  all  di- 
rections. Of  course  the  ascent  of  oil,  and  still  more  of  gas, 
must  be  equally  easy.  If  the  Trenton  in  our  State  ever 
had  any  store  of  the  precious  mineral  it  has  lost  that  whole 
store  long  ago.  There  can  be  none  left.  We  have  no  evi- 
dence that  it  ever  had  any. 


572  GEOLOGICAL   SURVEY    OF   PENNSYLVANIA. 

No  one  but  an  expert  geologist  can  compare  two  fields 
so  as  to  say  that  they  are  alike,  or  if  they  differ  how  they 
differ  ?  Twin  sons  of  one  father  may  resemble  each  other 
so  closely  that  they  pass  for  one  another  in  common  so- 
ciety ;  yet  one  may  be  ignorant  and  the  other  learned  ;  the 
one  a  poor  man  and  the  other  a  millionaire.  These  are  mat- 
ters of  original  constitution,  and  still  more  of  circumstance. 
Just  so  with  rocks  of  the  same  name,  age  and  character, 
but  either  deposited  under  different  conditions,  or  subse- 
quently subjected  to  different  adventures.  The  flat  lying 
Trenton  of  the  west  is  like  the  titled  nobleman  heir  to 
princely  estate  which  has  remained  unspoiled  and  still 
abounds  for  him.  The  Chambersburg  Trenton  is  like  a 
younger  son  who  has  spent  his  patrimony,  whatever  that 
was,  in  riotous  living,  and  there  is  no  more  of  it.* 


Iron  ore  in  the  body  of  the  Hudson  river  formation  No. 
JIJ,  in  its  500  miles  extent  of  outcrop  in  Pennsylvania,  is 
almost  unknown.  The  great  limonite  deposits  of  Ironton, 
Moselem,  and  Leathercracker  Cove  are  below  the  base  of  the 
formation.  And  yet  in  Eastern  New  York  beds  of  carbon- 
ate of  iron,  partly  crystallized  into  spathic  iron  ore,  partly 
weathered  into  limonite,  are  extensively  mined,  f 


*  "CHAMBERSBURG,  PA.,  July  25,  1887. — An  effort  is  now  being  made  in 
this  place  to  secure  subscriptions  for  boring  for  natural  gas.  A  number  of 
Chambersburg  people  who  have  visited  the  gas-producing  districts  of  Ohio 
believe  that  gas  can  be  found  underneath  the  surface  here,  because  of  the 
marked  similarity  of  some  sections  of  this  county  to  the  gas  fields  in  Ohio. 
Subscription  books  are  now  being  circulated  over  the  town,  and  it  is  thought 
the  necessary  amount  needed  for  the  experiment,  about  three  thousand  dol- 
lars, can  be  obtained.  Much  interest  is  displayed  in  the  project,  for  if  gas 
should  be  found  manufactories  would  undoubtedly  spring  up  in  large  num- 
bers, and  the  future  of  Chambersburg  would  be  almost  beyond  estimate." 

fSee  Siderite  basins  of  the  Hudson  River  Epoch,  by  James  P.  Kimball,  in 
Amer.  Jour.  Science,  August,  1890,  p.  155.  They  lie  about  a  mile  east  of  the 
Hudson  river,  between  Catskill  and  Germantown  RR.  stations,  Avest  of 
Copake,  in  a  range  parallel  with  Taconic  hills,  and  are  plicated,  some  of  the 
anticlinals  being  overthrown  and  compressed  westward  (giving  E.  dips). 
One  section  reads  :  Dense  fissile  slate,  weathering  white,  200'-f  ;  brecciated 
sandstone  (ferro-calcareons)  161' ;  sandstone  passing  into  conglomerate 
(ferro-calcareous)  120' ;  black  slate  and  sandy  shale  (interbedded)  50' ;  grits 
(ferro-calcareous,  seamed  with  calcite)  48';  carbonate  of  iron  (clay  iron- 


CHARACTER   OF   FORMATION   NO.  III.  573 

stone,  siderite,  sometimes  spathic)  44' ;  grey  slate  (weathering  into  drab 
shale  in  the  river  bluffs)  662,  to  the  bottom  of  boring  No.  1 ;  1300  in  all. 
These  lower  slates,  which,  as  Hall  and  Mather  maintained  (against  Em- 
mons)  are  Hudson  river  slates,  have  afforded  Hudson  river  fossils  to  Mr. 
T.  Nelson  Dale  near  Poughkeepsie.  (Am.  Jour.  Sci.  XVII,  1979,  page  377.) 
The  ore  body  is  a  group  of  clay  iron  stone  layers  separated  by  more  or  less 
ferruginous  and  calcareous  shaly  layers,  the  whole  group  varying  from  8  to 
60  feet,  and  evidently  deposited  in  separate  sea  side  lagoons,  into  which  riv- 
ulets from  the  hornblende  gneiss  country  brought  magnesian  deposits. 


574  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 


CHAPTER  XLVIII. 

The  roofing  slate  beds  of  No.  111. 

These  are  what  give  an  economical  value  to  the  forma- 
tion, and  redeem  the  slate  belt  of  the  Great  Valley  (geo- 
logically speaking)  from  almost  utter  barrenness.  Were  it 
not  for  its  roofing  slate  quarries,  one-half  of  the  Great  Val- 
ley would  be  merely  farming  land,  without  mineral  wealth 
of  any  kind  beneath  the  soil. 

At  present,  however,  there  are  no  roofing  slate  quarries 
in  the  Great  Valley  except  at  its  eastern  end  in  Lehighand 
Northampton  counties,  and  in  New  Jersey.  It  is  even 
doubtful  whether  or  not  the  beds  of  roofing  slate  continue 
to  range  through  the  formation  west  of  the  Schuylkill 
river.  The  signs  of  their  existence  in  Lebanon,  Dauphin, 
Cumberland  and  Fayette  counties  are  very  scanty,  al- 
though, here  and  there,  what  look  like  well  laminated  slate 
beds  do  crop  out ;  as  for  example  on  Conodoguinit  creek  ; 
where,  however,  the  slate  is  spoiled  with  pyrites.* 

It  is,  therefore,  of  considerable  importance  to  ascertain 
all  the  geological  facts  which  bear  upon  the  place  of  the 
roofing  slate  beds  in  the  formation  where  we  know  them 
to  exist,  in  order  that  their  outcrops  may  be  traced  along 
the  valley  where  their  existence  has  not  yet  been  certified. 

0??,  the  Delaware  rive?'  Formation  No.  Ill  appears  divisi- 
ble into  two  series:  an  upper,  and  a  lower. 

TJie  upper  series,  mostly  consisting  of  thicker  beds  (from 
one  foot  to  many  feet  thick  each)  may  be  considered  as  oc- 
cupying say  1540  feet  of  the  whole  thickness  of  the  forma- 
tion, f 

The  lower  series,  mostly  consisting  of  thin  beds  (less  than 

*At  Alton's  mill.    See  Rogers,  Geol.  Pa.,  1868,  Vol.  1. 

f  Measured  by  Dr.  Chance,  and  Mr.  Sanders,  from  the  base  of  No.  IV  in 
the  Delaware  water  gap  down  to  Williams'  old  slate  quarry. 


THE  ROOFING  SLATE  BEDS  OF  NO.  III.        575 

one  foot  in  thickness)  occupies  the  remaining  say  3700  feet, 
down  to  the  limestone  of  No.  II. * 

But  this  subdivision  of  the  formation  is  not  founded  upon 
any  other  distinction  than  the  one  apparent  fact  that  there 
is  a  general  tendency  to  heavy  beds  in  the  upper,  and  thin 
beds  in  the  lower  parts  of  the  formation.  As  for  the  mate- 
rial itself  there  seems  to  be  no  good  ground  for  the  distinc- 
tion. The  whole  mass,  5240  feet  (and  probably  more)  in 
thickness,  consists  of  beds  infinitely  various  in  thickness, 
from  30  feet  down  to  the  hundredth  of  an  inch — beds  of  slate, 
nearly  all  of  the  same  uniform  dark  grey  or  bluish-black 
color,  both  coarse-grained  and  fine-grained — with  occasional 
beds  of  sandstone,  which  are  not  persistent  but  either  run 
out  in  a  short  distance  or  change  into  ordinary  slate  beds.f 

In  the  section  along  the  eastern  bank  of  the  Delaware 
river  (see  page  554)  two  slate  quarries  are  shown,  one  on 
beds  which  come  1000  feet  below  the  bottom  sandstone  of 
No.  IV;  the  other  2350  feet  below  it4 

The  interval  of  1350'  would  represent  the  extreme  thick- 
ness of  the  roofing-slate  zone  in  the  formation  if  no  other 
quarry  beds  exists  still  lower,  that  is  in  the  remaining  3000 
feet  of  the  formation  down  to  the  limestone.  But  of  this 
we  cannot  be  sure,  and  in  fact  have  reason  to  doubt,  as  will 
presently  appear. 

On  the  Leliigfi  river  the  section  is  not  so  simple,  and 
measurements  are  not  so  easy.||  Here  a  broken  arch  in  the 
slates  has  given  rise  to  a  fault,  of  unknown  upthrow,  half 
a  mile  in  front  of  the  center  of  the  gap,  which  cuts  off  all 

*  Measured  from  opposite  Belvidere,  up  the  west  bank  of  the  Delaware  to 
R.  Shock's.  See  Report  D3,  Vol.  I,  p.  85. 

f  Dr.  Chance  remarks  (D3,  p.  150)  that  the  foreman  of  the  quarry  on  the 
Xew  Jersey  side  informed  him  that  the  diamond  saiv  used  there  for  sawing 
out  slabs  showed  that  the  diamonds  were  more  rapidly  worn  away  by  the 
fine-grained  than  by  the  coarse-grained  slate.  These  saws  cut  through  the 
slate  at  the  rate  of  1  inch  in  5  minutes,  50  strokes  forward  per  minute  (D3, 
p.  103). 

%  This  section,  constructed  by  Dr.  Chance  from  data  obtained  by  him  in 
making  his  contour  map  of  the  Water  Gap,  will  be  found  on  page  159  of 
Report  D3  ;  the  section  along  the  west  bank  of  the  river  on  page  157;  the 
map  in  Report  G6. 

i|  See  Dr.  Chance's  section  on  page  554  above,  and  map  in  G6. 


576  GEOLOGICAL   SURVEY    OF   PENNSYLVANIA. 

measurements  down  from  No.  IV  after  the  first  1000  to 
1500  feet.*  Other  rolls  of  considerable  magnitude  traverse 
the  slate  belt  between  the  fault  and  theSlatington  quarries, 
which  are  between  2  and  2|  miles  from  the  center  of  the  gap.f 
Then  we  get  the  crumpled  roofing  slate  belt  810  feet  thick; 
which,  although  crumpled,  can  be  measured  with  much  cer- 
tainy4  But  the  country  south  of  Slatington,  between  the 
quarries  and  the  limestone  is  so  full  of  folds  that  no  meas- 
urement of  strata  is  possible;  therefore  the  real  height  of 
the  lowest  Slatington  quarry-bed  above  the  limestone,  can- 
not be  made  out.§ 

All  that  we  can  say  then  is  (1)  that  the  uppermost  part 
of  the  great  slate  formation  at  the  Lehigh  water  gap  con- 
sists of  hard  sandy  slate  beds,  alternating  with  steel  colored 
fine-grained  sandstones,  beneath  which  come  soft,  shaly, 
bluish-black  slates;  (2)  that  more  than  1000'  down  from  the 
top  of  the  formation  lies  a  zone  of  roofing  slates  at  least 
1500'  thick;  and  (3)  that  underneath  this  comes  a  vast  rib- 
bon-slate series. 

The  Slatington  roofing  slate  zone  is  itself  made  up  of 
groups  of  beds  of  very  various  qualities,  each  group  con- 
sisting of  irregularly  arranged  thick  and  thin  beds,  some 
of  which  (both- of  the  thick  and  thin  beds)  have  the  roofing- 
slate  character. 

This  section  could  never  have  been  made  out  but  for  the 
extensive  exploitation  of  many  of  the  beds,  several  of  which 
are  brought  to  the  surface  again  and  again  by  the  rolling 

*  Even  the  thickness  of  the  slate  between  No.  IV  and  the  fault  is  uncertain 
owing  to  small  rolls  at  the  base  of  the  mountain;  but  it  cannot  be  less  than 
1000',  nor  more  than  1500'. 

f  Mr.  Sanders  has  endeavored  to  adjust  these  rolls  in  his  long  section, 
underneath  the  Slatington  section. 

J  See  the  Slatington  section  on  plates  L  and  LI,  p.  554  above. 

§  Dr.  Chance  expresses  the  opinion  that  between  the  fault  at  Slatington 
the  crumpling  is  so  great  as  to  suggest  a  possibility  that  the  rooting  slate 
belt  may  be  near  the  bottom  of  the  formation  (No.  Ill)  and  therefore  not 
far  above  the  limestone  (No.  II).  But  the  continuation  of  the  Slatington 
belt  westward  near  the  foot  of  the  mountain  to  be  described  directly,  and 
the  measurements  at  the  Delaware  water  gap  already  given,  seem  to  make 
it  quite  necessary  to  place  theSlatington  beds  in  the  upper  half  of  the  forma- 
tion (D3,  Vol.  I,  p.  151). 


THE  ROOFIXG  SLATE  BEDS  OF  NO.  III.        577 

of  the  measures,  as  shown  in  plate  L,  on  p.  544  above,  the 
most  important  consecutive  section  in  the  Great  valley.* 

Its  great  value  consists  in  its  proving  conclusively,  (1) 
that  the  roofing-slate  zone  of  the  formation  is  (here  at  least) 
1500  feet  thick  ;  (2)  that  in  this  zone  lie  many  different  beds 
of  workable  slate,  some  small,  others  of  great  size  ;  (3)  that 
although  the  zone  is  crumpled  the  roofing-slate  beds  hold 
their  special  character  over  a  space  sufficient  to  allow  them 
to  appear  again  and  again  at  the  present  surface  ;  (4)  that 
the  top  of  the  zone  is  more  than  1000'  down  from  the  top 
of  the  slate  formation  No.  Ill ;  and  therefore  (5)  that  the 
bottom  of  the  zone  must  be  a  long  way  up  from  the  top  of 
the  limestone  formation  No.  II. 

The  section  has  moreover  a  peculiar  value  for  geologists 
since  (6)  it  shows  what  a  small  percentage  of  the  whole 
thickness  of  No.  Ill  its  roofing-slate  beds  make,  even  where 
those  peculiar  deposits  make  their  best  show.  But  to  the 
business  world  this  is  an  unimportant  consideration.  Just 
as  a  few  five  and  ten  foot  coal  beds  in  3000  feet  of  coal  meas- 
ures, if  accessible  over  an  extensive  region,  can  make  the 
fortune  of  a  whole  commonwealth,  so  a  few  ten  and  twenty 
foot  roofing-slate  beds  in  5000  feet  of  slate  formation  may 
suffice  to  supply  an  extensive  commerce;  although  all  com- 
parisons between  the  two  cases  in  the  matter  of  supply  and 
demand  must  necessarily  be  omitted. f 

The  roofing  slate  beds  differ  from  the  slate  strata  among 
which  they  lie  (1)  by  the  special  fineness  of  mud  out  of 
which  they  were  made  ;  and  (2)  by  the  special  closeness 
and  evenness  of  the  cross  cleavage.  All  the  slates  of  No. 
Ill  are  more  or  less  foliated  ;  but  the  roofing  slates  are 
so  delicately  and  evenly  foliated  (not  parallel  to  the  bed 
planes,  but  across  them  at  various  angles)  that  they  can 
be  split  apart  into  school-slates,  roof-slates,  billiard-table 
slabs,  mantle  pieces,  and  fine  flags  of  various  market  values.  ^ 

*And  yet  it  is  imperfect,  inasmuch  as  its  continuity  is  broken  by  three 
concealed  intervals  of  100',  60'  and  100' ;  besides  the  indefiniteness  of  its  up- 
permost 400'  "which  includes  large  known  workable  beds." 

1 30, 000  tons  of  slates  is  a  fair  annual  shipment  from  the  Slatington  district ; 
50,000,000  tons  of  coal  from  the  anthracite  region. 

JSee  the  commercial  tables  in  D3,  p.  144  to  146. 
37 


578  GEOLOGICAL   SURVEY    OF   PENNSYLVANIA. 

The  belt  of  quarries  extends  30  miles  across  Northampton 
and  Lehigh  counties.  Numerous  towns  and  villages  have 
sprung  up  along  the  belt — between  East  Bangor  within  5 
miles  of  the  Delaware  river,  and  Slatedale  3  miles  west  of 
the  Lehigh  river.  Branch  railroads  have  been  made  for 
their  service  ;  and  new  localities  are  being  all  the  time  ex- 
plored. The  belt  is  wide  and  the  outcrops  numerous.  Some 
of  the  quarries  are  within  a  mile  of  the  North  mountain  ; 
others  (Chapman's  for  instance)  are  five  miles  from  the 
mountain,  and  two  miles  from  the  edge  of  the  limestone 
of  No.  II.  Isolated  quarries  have  even  been  opened  within 
a  mile  from  the  edge  of  the  limestone  belt.  But  all  the 
successful  quarries  seem  to  belong  to  the  Slatington  zone, 
the  outcrops  of  which  repeat  themselves  in  parallel  lines, 
with  alternate  north  and  south  dips,  over  a  geographical 
belt  of  surface  varying  in  width  from  one  to  three  miles 
according  to  the  number  of  the  rolls  and  the  flatness  or 
steepness  of  the  dips. 

But  as  yet  there  is  no  proof  that  any  one  of  the  quarry 
beds  extends  for  30  miles  or  for  10  miles  along  the  zone. 
The  continuance  for  any  distance  of  the  special  roofing 
slate  quality  of  any  layer  or  group  of  layers  in  the  slate 
formation  is  only  determined  for  the  individual  quarries, 
or  immediately  adjoining  quarries.  It  is  not  certain  there- 
fore that  a  fine  quarry  bed  may  not  exist  along  a  line  of 
ordinary  and  worthless  layers.  Every  exposure  should 
therefore  be  tested  for  itself.  The  place  of  a  coal  bed  in 
the  coal  measures  is  a  good  guide  for  the  coal  prospector  ; 
but  there  is  as  yet  no  satisfactory  proof  of  the  fact  that  the 
place  of  a  slate  bed  in  the  section  (if  discoverable)  is  a  sure 
guide  for  the  slate  prospector. 

Even  the  continuance  of  the  Slatington  zone  as  a  whole 
along  the  Great  Valley  westward  beyond  the  Schuylkill  is 
a  matter  of  doubt.  Roofing  slate  quarries  have  been  opened 
in  the  northeastern  part  of  Berks  county  which  undoubt- 
edly belong  to  the  Slatington  zone  ;  but  no  roofing  slate 
quarries  have  been  opened  in  western  Berks,  in  Lebanon, 
Dauphin,  Cumberland  or  Franklin  counties.  The  expla- 
nation of  the  fact  may  be  a  geological  one,  viz :  that  the 


THE  ROOFING  SLATE  BEDS  OF  NO.  III.        579 

Slatington  zone  thins  away  and  vanishes  in  Berks  county, 
going  west.  Or  the  explanation  may  be  a  financial  one, 
viz :  that  exploration  confines  itself  to  the  neighborhoods 
in  which  capital  has  been  planted  along  the  lines  of  already 
constructed  railroads,  etc.,  within  near  and  easy  reach  of 
the  principal  markets.  Thus  far,  no  inducement  for  ex- 
ploring the  slate  belt  of  the  valley  has  been  sufficiently 
strong  to  divert  capital  invested  in  the  roofing  slate  manu- 
facture into  new  channels  and  to  distant  districts.  The  cost 
of  testing  the  value  of  a  new  coal  opening  is  inconsiderable. 
The  cost  of  testing  the  real  value  of  a  slate  outcrop  for  roofing 
slate  quarry  purposes  is  a  serious  consideration.  It  requires 
the  eye  of  an  experienced  slate  miner  to  pass  judgment 
upon  a  slate  outcrop  as  to  whether  there  is  a  likelihood  that 
the  bed  will  furnish  roofing  slate  at  a  considerable  depth 
underground  ;  and  the  actual  profitableness  of  a  slate  quarry 
is  never  known  until  extensive  quarrying  has  been  done. 
This  the  great  number  of  abandoned  quarries  sufficiently 
demonstrates. 

Even  where  the  qualities  of  fineness  and  foliation  (split- 
ability)  is  possessed  by  a  roofing  slate  bed,  it  is  sometimes 
made  worthless  by  a  want  of  evenness.  The  excessive 
crumpling  of  the  slate  belt  applies  sometimes  to  the  mi- 
nutest details  of  a  quarry,  and  quarries  have  been  aband- 
oned because  the  slates  are  twisted  or  warped,  and  there- 
fore worthless.* 

The  ribbon  structure  of  the  roofing  slate  beds  is  their 
most  striking  peculiarity.  The  ribbon  pattern  seems  to 
cross  the  beds  ;  but  in  fact  it  shows  the  real  bedding  of  the 
original  deposits,  and  has  been  itself  subsequently  crossed 
by  the  cross-cleavage,  or  slaty  foliation,  produced  by  the 
tremendous  side  pressure  at  the  time  of  the  folding  of  the 
formation. f 

The  ribbon   pattern  is  made  by  the  different  colors  of 

*  The  Flynn  quarry  is  said  to  have  been  abandoned  for  this  reason  (see 
D3,  p.  104,  109).  See  also  the  bent  slates  in  the  Blue  Vein  quarry,  p.  117,  No. 
1566.  On  the  Jordan  the  cleavage  is  described  as  curly  (p.  124,  No.  184). 

fSee  D3,  p.  85;  and  Rogers'  Geol.  Pa.  1858,  Vol.  I,  p.  248. 


580  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

the  original  muddy  deposits,  some  gray,  some  black.*  The 
ribbons  at  the  Newville  slate  company's  quarry  are  "  tight 
and  some  of  them  jet  black"  (D3,  No.  119).  Those  at  the 
Blue  Vein  quarry  when  they  get  under  30'  or  40'  of  cover 
become  tight  (No.  1566).  An  expert  slate  miner  judges  of 
the  value  of  slates  partly  by  its  ring.-\ 

Westward  extension  of  the  roofing  slates. 

West  of  the  Lehigh  river  the  Slatington  roofing  slate  beds 
run  on  towards  the  Schuylkill.  The  old  Diamond  slate 
quarry  4  miles  west  of  Slatington  (3  miles  from  the  North 
mountain)  was  worked  to  a  depth  of  250  feet  and  abandoned. 
A  quarry  near  Pleasant  Corner  (7  miles)  is  abandoned.  The 
Laurel  hill  quarry  and  Lynnport  quarry  (11  miles)  are  each 
60'  deep4 

Near  the  Berks  county  line  (15  miles)  are  the  New  Slate- 
ville  quarries,  on  the  two  sides  of  a  roll,  both  on  a  bed  4' 
thick  and  both  abandoned.  §  On  the  other  side  of  the 
county  line  in  Berks  county  the  Centennial  quarry  is  80' 
deep  ;  and  near  it  an  abandoned  quarry  on  a  20'  bed.  West 
of  this  no  roofing  slates  have  been  found,  but  flagstone 
quarries  have  been  opened.  || 

There  arises  then  a  practical  question : — how  is  the 
roofing  slate  sub-division  of  the  slate  belt  to  be  recognized 
along  the  valley  ? 

(1)  First,  by  its  distance  from  the  top  or  bottom  of  ths  for- 
mation, as  described  above,  /.  e.  1000'  to  2000'  beneath  the 
sandstone  No.  IV  of  the  mountain  crest, — 2000'  or  3000' 
above  the  limestone.  As  the  latter  measurement  is  almost 

*  The  best  at  the  West  Washington  quarry  is  called  "the  grey  bed"  (D3,  98). 

f  Thin-bedded  slates,  dark  blue,  with  a  good  ring  (p.  113,  No.  135).— The 
slates  have  a  good  ring,  dark  color  and  even  cleavage  (p.  114,  No.  146).— The 
slates  lei't  on  the  pile  are  thick  and  have  a  poor  ring  (p.  109,  No.  ]  14)  etc. 

J  The  one  lies  one  mile  from  the  mountain  the  other  two  miles ;  at  the 
first  the  dip  is  vertical  which  if  it  lasted  all  the  way  to  the  mountain  would 
make  the  bed  5000'  below  the  sandstone;  in  fact  the  distance  is  much  less. 

§  These  are  6000'  from  the  sandstone  outcrop. 

[|  In  Albany  township  west  of  Kempdou  ;  in  Perry  township  (half-way 
between  Leonhartsville  and  Virginsville)  where  3'  flags  10  feet  long  are 
obtained ;  and  near  Shoemakersville. 


THE  ROOFING  SLATE  BEDS  OF  NO.  III.        581 

an  impossibility  on  account  of  the  folds  in  the  middle 
slate  limestone  zone  of  the  valley  the  former  measurement 
(i.  e.  from  the  sandstone  No.  IV  down)  is  the  only  one  avail  - 
ble.  When  the  dips  in  the  foot  hills  of  the  mountain  are 
10°  to  20°,  the  roofing  slate  belt  must  be  looked  for  a  mile 
or  so  from  the  mountain  ;  when  the  dips  are  50°  to  60°,  it 
must  be  looked  for  close  to  the  foot  of  the  mountain  slope. 

But  it  must  be  remembered  that  the  whole  breadth  of  the 
slate  belt  is  so  folded,  that  the  roofing  slate  zone  (if  it  exists) 
will  come  to  the  surface  several  (or  even  many)  times  be- 
tween the  mountains  and  the  edge  of  the  limestone. 

To  show  how  important  this  consideration  is  we  must  go 
back  for  a  moment  to  Lehigh  county.  There  are  three  places 
west  of  the  Lehigh  river  where  roofing  slate  quarries  have 
been  worked  nearer  the  edge  of  the  limestone  than  the 
Slatington  quarries  are  to  the  mountains; — thus,  in  N. 
Whitehall  township  (2m.  S.  W.  of  Laury's,  P.  O.)  the  North 
Peach  Bottom  quarry  (250x200'  long  and  90'  deep)  is  only 
f  mile  from  the  edge  of  the  slate.  Here  the  beds  are  flat, 
but  in  a  downfold,  and  therefore  cannot  lie  more,  than  2000' 
above  the  limestone. 

Again  in  S.  Whitehall  township  between  Orefield  and 
Crackenport  is  an  abandoned  quarry  on  Huckleberry  ridge, 
a  long  downfold  (synclinal)  of  slate  between  two  areas  of 
limestone  and  only  f  mile  wide.  Although  the  slates 
are  here  vertical,  there  is  only  room  for  1320'  on  both  dips 
or  760'  on  each  dip.  It  seems  as  if  we  must  insert  a  roofing 
slate  zone  near  the  lower  limit  of  the  foundation. 

Again,  east  of  Seipstown,  and  4  miles  west  of  the  last, 
there  is  an  old  quarry  not  far  back  of  the  limestone  edge, 
dip  70°.  But  here  there  is  room  enough  for  perhaps  2000' 
of  distance  from  the  limestone  up  to  the  slate, 

The  truth  seems  to  be  that  the  main  belt  of  roofing  slate 
runs  along  more  than  half-way  up  in  the  formation  ;  but 
that  there  exists  beds  of  roofing  slate  in  the  lower  half  of 
the  formation,  some  of  which,  in  some  neighborhoods,  may 
possess  commercial]  value.  And  this  explains  a  fact  first 
noticed  by  the  First  Geological  Survey  of  Pennsylvania, 
and  published  by  Prof.  Rogers  in  his  final  report,  Vol.  1, 


582  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

page  260: — After  saying  that  "in  no  part  of  the  slate  for- 
mation" from  the  Susquehanna  to  Maryland  "  have  the 
strata  the  structure  and  cleavage  to  produce  roofing  slate, 
he  adds  :  ' '  The  nearest  approximation  to  that  useful  variety 
yet  seen  occurs  in  the  bed  of  the  Conedoguinit,  above 
Alter' s  Mill,  where  the  rock  is  traversed  by  cleavage- 
planes  of  tolerable  regularity,  but  its  usefulness  is  destroyed 
by  its  containing  sulphur et  of  iron."  As  the  Conedoguinit 
runs  along  the  southern  edge  of  the  slate  belt,  and  some- 
times cuts  a  little  into  the  limestone  belt,  these  cleaved  slates 
must  belong  to  the  lower  part  of  the  slate  formation  No.  III. 

So  in  Franklin  county  1£  miles  southeast  of  Orrstown  on 
the  road  from  Orrstown  to  the  railroad,  there  is  a  fine  road- 
cutting  30  feet  long  by  15  feet  high  which  showed  the 
folded  slates  with  a  roofing  slate  cleavage  at  right  angles 
to  the  folds  and  the  accompanying  local  map  shows  how 
close  the  locality  is  to  the  southern  border  of  the  slate  belt, 
and  therefore  in  the  lower  part  of  the  formation. 

Red  slate,  which  is  not  rooting  slate,  has  not  been  ob- 
served in  Northampton  county  ;  nor  in  Lehigh  county  ex- 
cept within  a  few  miles  of  the  Berks  county  line  1£  m. 
N.  E.  of  Seiberlingsville  in  Weisenburg  township  No.  197, 
D3,  p.  155);  but  in  Berks  county  it  is  frequently  noticed 
by  Mr.  Sanders,  e.  g.  in  Albany  township,  west  o  f  Kemp- 
don  (No.  206)  red  slate  spotted  with  green  ;  half  a  mile  S. 
of  Kempdon  (No.  208). 


Notes  on  the  Bangor  slate  belt. 

By  R.  M.  JONES. 

At  my  request  Mr.  Jones  addressed  me  the  following 
letter,  embodying  in  his  own  way  valuable  information, 
which  it  is  natural  that  he  the  pioneer  of  this  important 
industry  alone  knows,  or  knows  better  than  any  one  else. 

BANGOR,  October  10,  1S8J. 

"According  to  my  promise,  I  write  to  you  concerning  the 
slate  interests  of  our  country,  and  particularly  of  Northamp- 
ton countv 


THE  ROOFING  SLATE  BEDS  OF  NO.  III.        583 

"The  slate  belt  of  Fail-haven  and  Paultney,  Vermont,  runs 
through  Middle  Granville  and  Granville  Corners  in  Wash- 
ington county,  N.  Y.  to  Pawlet  Wagen.  In  all  the  above 
named  places  there  are  large  and  extensive  quarries  in  full 
operation.  In  this  part  of  the  belt  the  slates  are  of  various 
colors,  viz:  purple,  green  and  red.  This  belt  thence  runs 
through  North  Hoosick  and  Hoosick  Falls  in  Rensselaer 
county  into  Columbia  county,  N.  Y.  In  this  county  the 
stratum  makes  a  large  dip  which  runs  under  the  bluestone 
of  the  Hudson  river  division  below  Kingston,  N.  Y.  This 
dip  is  over  sixty  miles  in  extent.  The  slates  are  nothing  in 
all  this  distance  but  a  conglomerate  slate  of  no  value  what- 
ever as  slates.  The  finest  slate  of  any  value  we  will  meet  in 
this  stratum  is  in  Sussex  county,  N.  J.,  which  is  of  an  in- 
ferior quality,  properly  belonging  to  the  Chapman  division, 
what  is  called  the  wavy  or  ribbon  slate  adapted  only  for 
local  trade.  In  the  north  part  of  the  stratum  what  are  called 
the  Bangor  slates  are  considered  in  England  and  the  Conti- 
nent (where  they  know  what  to  look  for  in  slates)  the  trade 
mark  of  America,  so  much  so  that  all  slates  shipped  from 
this  country  are  called  Bangor  slates  to  gain  credit  and 
reputation.  The  slates  of  Sussex  and  Warren  counties 
N.  J.  do  not  amount  to  much.  We  have  made  a  close  ex- 
amination of  the  strata  between  the  Delaware  Water  Gap 
on  the  Jersey  side  through  Warren  and  Sussex  counties, 
N.  J.,  into  Orange  county,  N.  Y.,  and  we  find  the  article  of 
poor  quality,  more  of  the  earthenware  nature  than  slates, 
lacking  the  principal  quality  of  the  right  kind  of  slates  for 
roofing  or  school  slates,  which  is  toughness.  There  is  an  old 
quarry  at  the  Delaware  Water  Gap,  one  on  the  Jersey  side  of 
the  river,  opened  over  sixty  years  ago  by  a  gentleman  named 
O.  Evans,  a  native  of  Carnarvonshire,  North  Wales.  He 
worked  the  quarry  successfully  for  a  number  of  years  until 
his  death,  and  accumulated  considerable  property  and 
money  through  the  working  of  this  quarry.  On  the  west 
side  of  the  Delaware  river  near  the  gap,  nearly  opposite  the 
Evans  property,  is  another  slate  quarry  near  the  village  of 
Slateford,  in  Northampton  county,  Pa.  This  is  supposed  to 
be  the  oldest  slate  quarry  in  America,  the  quality  of  the 


584  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

slate  is  the  same  as  in  the  Jersey  part  of  the  stratum  ;  the 
stratum  makes  a  southwest  dip  here  of  over  live  miles  in 
length,  appearing  and  outcropping  at  the  Boyer  farm  and 
other  places  in  that  locality  in  that  neighborhood.  The 
quality  of  the  article  in  those  places  for  roofing  or  school 
slate  is  only  ordinary.  This  stratum  runs  southwest  through 
the  Brushy  Meadows  Valley,  East  Bangor,  Bangor,  Pen- 
argyle  and  the  Wind  Gap.  And  right  here  I  would  say 
that  the  great  slate  center  of  our  state  is  destined  to  be  be- 
tween East  Bangor  and  about  one  mile  southwest  of  the 
Wind  Gap ;  a  belt  of  slates  near  ten  miles  in  length  from 
northeast  to  southwest,  and  about  one  mile  in  width  or  thick- 
ness from  north  to  south.  We  have  a  number  of  quarries 
opened  and  in  course  of  opening  in  this  section.  The  prin- 
cipal quarries  are  the  following:  First,  in  East  Bangor  the 
celebrated  Seek-no-further  property,  the  old  Delp  property 
the  Meyers,  Bray  and  Short  property,  the  Star  slate  quarry, 
the  Standard  slate  property,  the  Bangor  Central,  the  Howell 
property,  the  New  Bangor  quarries,  the  Old  Bangor  quar- 
ries, the  Bangor  Royal,  the  Bangor  Unison,  the  North  Bangor 
and  the  Washington  slate  property.  All  of  these  quarries 
except  the  little  Washington  are  in  full  operation  ;  and 
there  is  more  slate  made  in  this  section  of  the  country  than 
in  any  other  one  part  of  the  United  States.  And  then  we 
must  take  into  consideration  that  all  these  improvements 
are  of  a  very  recent  date.  R.  M.  Jones  started  nearly  all 
these  quarries  since  July,  A.  I).  1865.  When  he  started  the 
Old  Bangor  quarry  on  the  first  of  August,  1866,  Bangor 
under  the  name  of  the  New  Village  contained  less  than 
twenty  inhabitants.  Now  it  is  made  into  a  borough  of  near 
three  thousand  souls  ;  and  if  all  who  work  in  the  borough  of 
Bangor  would  live  in  it  we  would  have  a  population  of  over 
nine  thousand  inhabitants.  Bangor  was  named  after  old 
Bangor  in  Wales,  and  is  considered  by  all  the  finest  mining 
town  in  the  State  of  Pennsylvania. 

"Two  miles  and  half  northwest  of  Bangor  on  this  slate  belt 
is  the  town  of  Penargyl ;  there  is  a  very  geart  body  of  large 
beds  of  slate  in  this  locality.  The  cleavage  in  this  place  is 
mostly  horizontal,  the  ribbons  pitching  from  35  to  45 


THE   ROOFING   SLATE  BEDS   OP   NO.   III.  585 

degrees  southeast.  When  we  talk  about  a  bed  of  slates  we 
mean  that  portion  of  the  rock  that  lays  between  ribbons 
or  black  streaks  that  run  across  the  cleavage  and  grain  of 
the  slates.  These  streaks  only  occur  in  this  stratum  in 
the  slates  of  New  Jersey  and  Pennsylvania ;  there  are  no 
rubbons  or  black  streaks  in  this  stratum  in  the  States  of 
New  York,  Vermont  or  New  Hampshire,  nor  Virginia  ;  but 
we  find  the  ribbon  in  part  of  the  State  of  Maryland  near 
the  Point  of  Rocks.  There  is  much  difference  in  the  quality 
of  these  ribbon  slates.  In  some  parts  of  the  belt,  especially 
in  the  north  part  of  this  stratum  the  ribbon  slates  will  not 
do  for  roofing  slate  ;  but  the  south  part  of  the  belt  is  well 
adapted  for  roofing  as  a  second  quality  of  slates  ;  and  the 
fact  of  the  matter  is  that  all  ribbons  or  wavy  slates  are 
nothing  more  than  second  grade  of  roofing  materials.  Still 
there  is  a  large  quantity  of  this  kind  of  slate  recommended 
by  architects  in  your  city  and  some  parts  of  the  adjoining 
counties.  Some  do  it  from  ignorance  of  the  true  quality  of 
slates  ;  but  the  most  of  our  architects  specify  this  article  of 
roofing  because  it  pays  them  to  do  it ;  and  th«  only  way  a 
second  quality  of  slates  of  this  kind  has  succeeded  so  well 
is  by  having  percentage  paid  to  that  class  of  men  who  specify 
what  material  shall  be  used  for  the  buildings.  When  such 
stuff  is  sent  to  England  where  they  want  first  quality  of 
slates  they  are  not  accepted. 

"At  Pen  Argyl  two  and  one-half  miles  from  Bangor  there 
are  some  very  fine  slate  quarries  opened  by  Jung  &  Co., 
John  &  Rich,  Jackson  &  Co.,  Stean,  Jackson  &  Co.  and 
the  Albion  Slate  Company,  and  Henry  Fulmer.  All  these 
quarries  contain  large  beds  of  slates  ;  and  slates  can  be  pro- 
duced in  this  section  of  the  slate  belt  at  from  thirty  to  forty 
per  centum  cheaper  than  at  other  localities  on  this  stratum  ; 
because  from  a  large  bed  of  slate  we  can  make  large  sizes  of 
slates.  For  instance,  it  only  takes  98  slates  of  24  x  14  to  make 
a  square  of  slates  (that  covers  100  feet  of  roofing);  while  it 
will  take  533  slates  of  12  inch  by  6  inch  slates  to  make  a 
square  (or  100  feet) ;  and  while  the  mechanics  are  making 
one  square  of  12x6  they  will  make  five  and  one-half  squares 
of  24 X 14  inch  slates.  Hence  the  importance  of  selecting  slate 


586  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

properties  containing  large  beds  of  slate.  In  this  part  of 
the  stratum  the  slates  are  not  adapted  for  school  slates  ;  but 
in  the  south  part  of  this  the  mountain  strata  is  where  the 
school  slates  can  be  procured.  About  one-half  a  mile  south 
of  Pen  Argyl  on  the  Bangor  and  Portland  Railroad  a  large 
deposit  of  a  very  fine  quality  of  school  and  roofing  slates 
was  discovered  by  R.  M.  Jones  of  Bangor,  Pa.  at  a  place 
called  the  Grand  Central  quarry  which  are  of  a  fine  texture 
and  very  dark  color.  Also  Mr.  Jones  has  discovered  a  large 
plant  in  the  north  part  of  the  slate  stratum  of  the  Pen 
Argyl  division,  which  is  about  three  miles  southwest  from 
Pen  Argyl.  This  is  a  large  field  for  enterprise.  The  slate 
stratum  pitches  like  the  waves  of  the  sea.  The  general  dips 
are  about  three  miles.  And  right  here  I  would  like  to  draw 
your  special  attention  to  the  fact  that  the  same  bed  of  slate 
loses  its  strength  and  toughness  in  its  outcropping.  On  the 
down  dip  the  article  will  split  from  the  side  across  the  grain 
or  cleavage  readily,  but  on  the  outcropping  it  will  not  split 
across  the  grain  or  cleavage  at  all.  About  one  mile  from 
the  Wind  Gap  southwest,  the  position  of  the  ribbon  changes 
to  nearly  a  vertical  position,  and  keeps  on  that  way  princi- 
pally all  through  Northampton  county  to  the  Lehigh  river 
at  Walnutport ;  and  the  cleavage  dipping  about  seventy- 
five  degrees  southeast.  The  stratum  is  much  conglomerated 
from  the  first  mentioned  points  to  the  Lehigh  river.  There 
are  a  few  places  in  and  between  the  aforesaid  points  where 
good  quarries  are  and  may  be  opened.  At  the  Little  Gap 
Hower  &  Son  have  a  good  slate  property.  About  one  and  a 
half  mile  southwest  of  the  Howard  quarry  a  good  quarry 
may  be  opened  on  the  same  beds.  At  Berlinsville  there  are 
several  quarries  opened  and  in  course  of  being  opened.  At 
a  place  called  Himbach  several  good  quarries  within  about 
two  miles  from  Walnut  Port  are  well  adapted  for  both 
school  and  roofing  slates,  but  there  is  considerable  con- 
glomeration in  the  slate  belt  from  the  Wind  Gap  to  Walnut- 
port,  and  investments  should  be  made  with  great  care  and 
close  examination  of  the  premises. 

''The  whole  width  of  the  slate  belt  from  about  one  mile 
above  Siegfried's  bridge  on  the  Lehigh  river  to  the  Lehigh 


THE  ROOFING  SLATE  BEDS  OF  NO.  III.        587 

Gap  is  near  ni;ie  miles,  but  in  all  that  distance  there  is 
not  over  three  quarters  of  a  mile  of  what  might  be  termed 
a  No.  1  article  of  slates  adapted  for  school  and  roofing 
slates.  This  commences  about  a  quarter  of  a  mile  below 
the  Queens  hotel  at  Walnutport  and  runs  up  the  river 
towards  the  Lehigh  Gap  less  than  half  a  mile  north  of 
Walnutport  as  we  proceed  northeast  from  Walnutport. 
Beyond  Berlinsville  the  good  stratum  is  about  a  quarter 
of  a  mile  wider.  From  the  Little  Gap  to  the  Wind  Gap  the 
belt  is  much  conglomerated  and  full  of  posts  and  crystals, 
which  makes  it  a  very  dangerous  field  to  operate  in."* 

*Mr.  Jones'  letter  is  brought  to  a  close  with  a  beautiful  verse  of  poetry  in 
the  Lower  Silurian  language  of  Wales,  the  age  of  which  is  not  quite  so  remote 
as  that  of  the  slate  belt,  but  nevertheless  has  this  in  common  with  it,  that  the 
vowel  foliation  crosses  and  obscures  the  original  consonantal  stratification. 
I  would  gladly  give  it  here  had  I  any  friend  at  hand  learned  enough  to  verify 
the  orthography. 


588  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 


CHAPTER  XLIX. 

The  slate  quarries  of  Northampton  and  Lehiqh  counties 

in  1882. 

In  1883,  Mr.  Sanders'  notes  on  the  quarries  of  the  slate 
belt  were  published  in  report  D3,  Vol.  I,  pages  86  to  133. 
No  subsequent  resurvey  of  the  belt  could  be  made,  as  the 
corps  were  fully  occupied  in  other  counties.  New  opera- 
tions, especially  upon  the  Lehigh  river  above  Slatington, 
deserve  description  for  which  I  have  no  data.  The  follow- 
ing list  and  short  mention  of  the  quarries  as  they  were  be- 
fore 1883  will  suffice  to  show  the  character  of  the  belt.* 

In  Northampton  Co.,  Upper  Mount  Bethel  township. 

1.  Washington  Brown's  Quarries,  on  the  slope  of  the 
mountain  overlooking  the  Delaware,  recently  opened  ;  75 X 
75x40  feet;  600'  below  the  Oneida  sandstone;  dip  25°  N. 
40°  W.  cleavage  flat.     The  slates  have  a  good  color  and 
are  smooth. 

2.  John  Morrison's  Quarry,  at  the  foot  of  the  steep 
slope  of  the  mountain,  800  to  900  feet  below  the  Oneida ; 
opened  in  1877  ;  150x100  feet ;  five  to  fifteen  of  Drift  on 
top  of  the  slates,  which  are  decomposed  under  the  drift ; 
dip  20°,  N.  40°  W.,  cleavage  flat.     The  beds  are  four  feet 
and  under  in  thickness. 

•?.  J.  W.  Williams'  Quarry,  half  a  mile  northwest  of  Slate- 
ford  ;  150x150x100;  30  to  50  feet  of  Drift  on  top,  with 
boulders  2  feet  in  diameter ;  thickest  bed  4  feet ;  dip  20°, 
N.  10°  W.  ;  cleavage  2°,  S.  10°  E.  At  the  factory  the 
ribbon  slate  is  seen  in  the  bed  at  the  creek  fifty  feet  below 
the  quarry. f 

*The  numbers  are  those  in  D3,  and  are  found  on  the  county  maps  of  the 
D3  atlas.  They  begin  at  the  Delaware  river  and  run  in  a  general  westward 
order  across  Lehigh  county  into  Berks. 

fThis  was  the  first  slate  quarry  opened  in  Pennsylvania  viz:  by  Mr. 
Williams  auout  the  year  1812.  It  is  described  in  Prof.  H.  D.  Rogers'  Geol- 
ogy of  Pennsylvania,  Vol.  I,  p.  248  as  follows  ;  but  the/cm^  is  not  now  vis- 
ble,  being  buried  under  water  and  debris. 


SLATE  IN  NORTHAMPTON  AND  LEHIGH  COUNTIES.       589 

4.  Emory  Pipher  quarry,  a  few  hundred  yards  west  and 
slightly  below  Morrison's  quarry;  abandoned;  200x100 
feet ;  beds  seen  small ;  dip  in  the  south  and  central  part 
of  the  quarry  flat ;  at  the  north  edge  20°,  N.  40°  W.  ; 
cleavage  20°  south. 

J.  Snowden  quarry.  (Fig.  1  p.  548) — This  quarry  owned 
by  H.  P.  Jones  is  500  yards  northwest  of  Williams  quarry  ; 
150x150x40  ;  15'  of  drift  on  top.  Two  of  the  largest  beds 
are  14  and  12  feet  thick  ;  cleavage  26°  south.  At  the  north 
side  of  the  quarry  there  is  a  fault  showing,  probably  the 
same  fault  as  described  by  Prof.  Rogers  in  the  Williams 
quarry  ;  beds  south  of  the  fault  dip  40°  north.  Product  in 
1882  about  150  squares  a  month.  Started  in  1870. 

6.  The  quarry  (Fig.   2)   worked  by  William  Manus  of 
Scran  ton,  on  Peter  Fry's  farm  ;  300x100  feet  and  full  of 
water  ;  no  large  beds  to  be  seen. 

7.  L.  Or  one"  s  farm,  \%  miles  north-east  of  East  Bangor, 
a  small  abandoned  quarry,  50x50x15;  dip  20°  N.  40°  W., 
with  flat  cleavage;  largest  bed  2  feet  thick;  cleavage  twisted. 

8.  J.    Oyer's  farm,   li  miles  north  of    East  Bangor; 
100  x  100  feet,  full  of  water  ;  beds  3  feet  thick  and  less  ;  10  feet 
of  Drift;  dip  10°.  N.  40°  W.  ;  cleavage  20°.  S.  20°  W. 

9.  Opposite  Belvedere.     The  contact  of  the  slates  and 
•  limestones  on  the  Delaware  river  shows  by  a  high  ridge. 

The  dip  is  70°,  S.  20°  E.  and  the  cleavage  25°,  S.  20°  E.  The 
same  dip  shows  for  three  quarters  a  mile  up  the  river. 
The  slates  are  thin  bedded,  compacted  together,  making 
solid  beds,  in  some  cases  10  feet  thick,  between  loose  rib- 
bons. From  the  river  road  up  north  until  the  road  lead- 
ing from  Centreville  to  Porterville  is  reached,  nothing  but 
ribbon  slates  show. 

11.  C.   Wolfs  farm  on  Martin's  creek  half  a  mile  east  of 
the  township  line,  a  small  excavation  ;  dip  15°,  N.  40°  E.  ; 
cleavage  60°,  S.  40°  E.  ;  ribbon  slates. 

12.  East   Bangor  quarry  No.  3,  Bry  &  Short;    north 
side  of  the  railroad,  east  of  the  wagon  road  leading  north 
from  East  Bangor  ;  150x50x50  ;  dip  5°,  S.  40°  W.  ;  cleav- 
age 20°,  S.  10°  W.  ;  beds  rather  small. 

13.  Old  East  Bangor  quarry.     Fisler  &  McKean  ;  across 


590  GEOLOGICAL   SUKVEY   OF   PENNSYLVANIA. 

the  road  from  East  Bangor  No.  1  ;  250x150x50,  with  water 
in  the  bottom;  dip  flat;  cleavage  20°,  S.  10°  W.  ;  largest 
bed  3  feet  thick. 

14.  East  Bangor  No.  2.     Bry  &  Short,  300  yards  west  of 
the  old  East  Bangor  quarry;  200x450x60;  dip  10°,  N.  ; 
cleavage  20°,  south  ;  largest  bed  four  feet. 

15.  East  Bangor  No.  1.     Bry  &  Short,  between  East 
Bangor  No.  2  and  the  railroad  ;  250x200x100  ;  dip  20°,  N. 
20°  W. ;  cleavage  20°,  S.  20°  E.  ;  beds  16,  10  and  11  feet  in 
length  along  the  cleavage. 

16.  Star  quarry.     Major  Aims,  500  feet  west  of  the  East 
Bangor  No.  2;  200x200x50;  cleavage  20°,  south.     There 
is  an  old  quarry  (not  being  worked)  just  south  of  this,  on 
the  same  beds  as  the  East  Bangor  No.  1. 

Washington  township. 

Colon  Aims'  quarry,  close  to  the  township  line,  on  the 
north  side  of  the  creek  ;  100x50x40  ;  with  10  to  20  feet  of 
Drift  on  top ;  dip  25°,  N.  40°  W.  ;  cleavage  20°,  S.  4°  E.  ; 
beds  all  small.  Some  of  the  slates  are  made  from  single 
beds,  while  others  have  two  or  more  beds  in  them.  The 
slates  made  from  the  ribbon  slate  are  mostly  bent ;  others 
are  good  except  a  few  which  are  slightly  bent. 

17.  Bangor  Central  quarry,  %  mile  west  of  the  township 
line  on  north  side  of  creek;  200x100x40  feet  deep;  dip 
25°,  N.  40°  W.  ;  cleavage  10,°  S.  40  E.  ;  make  slate  out  of 
single  beds,  and  from  two  or  more  beds  ;    some  of   them 
slightly  bent ;  beds  all  small, 

18.  Bangor  Old  quarry,  500  feet  west  of  the  Bangor  Cen- 
tral ;  side  hill  cut,  50  feet  deep  at  the  face,  with  from  15  to 
30  feet  of  gravel  on  top ;  dip  25°,  N.  40°  E.  ;  cleavage  15°, 
S.  40°  W.  ;  slates  made  from  single  beds  and  from  two  or 
more  beds  ;  some  much  bent. 

19.  Powell's  quarry,  on  south  side  of  railroad,  f  mile  east 
of  Bangor  ;  side  hill  cut,  300  feet  long,  by  from  50  to  100 
feet  broad,  and  80  feet  deep  ;  dip  25°,  N.  40°  W.  ;  cleavage 
15°,  S.  40°  E.  ;  5  to  15  feet  of  *Drift  on  top  ;  largest  bed  4 
feet.     The  slates  on  the  dumps  are  made  from  one  or  more 


SLATE  IN  NORTHAMPTON  AND  LEHIGH  COUNTIES.        591 

beds  ;  all  of  these  with  two  beds  in  them  were  bent,  some 
few  of  the  others  were  also  bent. 

20.  Bangor  Valley  quarry,  a  few  hundred  feet  west  of 
Powell's  quarry;  200x150x50  feet;  dip  20°,  N.  50°  W.  ; 
cleavage  10°,  S.  50°  E.  ;  5  to  10  feet  of  Drift  on  top  ;  largest 
bed  3  feet ;  quarry  on  top  of  the  Bangor  axis  ;  slates  above 
the  Bangor  slates. 

21.  Bangor  quarry  (Fig.  3),  £  mile  east  of  Bangor  ;  600 x 
400x130.     A  synclinal  axis  passing  through  the  center  of 
it,  about  70  feet  below  the  surface  ;  the  plane  of  the  axis 
dips  5°  to  the  north,  the  cleavage  also  dips  5°  north.    There 
is  30  feet  of  Drift  on  top  of  the  south  side  of  the  quarry  ; 
largest  bed  9'  6"  ;  synclinal  axis  pitches  to  the  west,  being 
the  same  synclinal  that  shows  in  the  Washington  quarry 
and  the  Bangor  Union.     The  slate  in  the  north  end  of  the 
quarry  would  come  to  the  surface  at  the  railroad,  on  a  line 
between  the  Washington  and  Bangor  Union  quarries.     The 
slate  on  the  south  side  of  the  quarry  probably  shows  in 
the  Washington  quarry.    There  are  60  men  engaged  in  quar- 
rying,  besides  the  drivers,  engineers  and  splitters.     The 
quarry  is  worked  by  horses  and  carts  and  also  by  three  cable 
derricks  run  by  separate  engines.     There  are  42  shanties  in 
operation.     (1882.) 

82.  Washington,  quarry  (Fig.  4),  Fulmer  &  Wagner,  just 
west  of  the  Bangor  quarry  ;  150  X 100  ;  reported  70  feet  deep  ; 
20  feet  of  Drift  on  top  ;  cleavage  12°,  N.  30°  W. 

23.  Bangor  Union  quarry  is  some  250  x 250  x  130  feet  deep 
at  the  deepest  place,  with  from  11  to  20  feet  of  Drift  on  the 
surface ;  largest  bed  4  feet  thick.  The  synclinal  axis 
which  shows  in  the  Bangor  quarry  also  shows  in  this  one, 
but  the  plane  of  the  axis  dips  slightly  to  the  south  instead 
of  to  the  north  as  in  the  Bangor.  The  quarry  is  worked  by 
5  cable  derricks,  which  supply  material  to  20  shanties.  The 
derricks  are  run  by  one  engine,  which,  working  a  line  of 
shafting,  connects  with  the  cable  derricks  by  conical  friction 
wheels.  The  quarry  is  running  on  roofing  and  school  slates. 
Those  slates  made  just  below  the  turn  of  the  axis  are  bent  ; 
the  others  are  good.  The  beds  in  the  quarry  are  tight  and 
some  of  the  slates  are  made  across  the  beds.  (1882.) 


592  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

24-  North  Bangor  No.  1 ;  south-east  corner  200  feet  west 
of  the  north-west  corner  of  the  Bangor  Union  ;  200x200x 
40 ;  20  feet  of  Drift,  and  they  make  slate  one  foot  below 
it ;  cleavage  10°,  S.  30°  E  ;  dip  45°,  S.  30°  E. ;  two  largest 
beds  4  feet ;  there  is  a  bed  measuring  10  feet  along  the 
cleavage ;  at  the  south  end  of  the  quarry  this  10  foot  bed 
has  two  feet  of  rock  on  the  top  of  it,  making  only  8  feet  of 
it  workable.  The  beds  show  all  the  way  across  the  floor  of 
the  quarry  ;  all  of  them  are  under  4  feet  in  thickness. 

.25.  North  Bangor  No.  2,  a  few  hundred  feet  north  of 
No.  1  ;  150x100,  40  feet  deep ;  dip  35°,  S.  30°  E.;  cleavage 
15°,  S.  30°  E. ;  beds  under  4  feet ;  I  was  told  there  were  two 
measuring  12  feet  in  the  quarry,  but  could  not  see  them  as 
it  was  full  of  water. 

26.  North  Bangor  No.  3  (Fig.  5  p.  548  above),  200'  north 
of  No.  2;  side  hill  cut  150x200x100;  of  irregular  shape 
and  worked  at  the  centre  of  the  synclinal  axis  ;  plane  of 
axis  dips  15°,  S.  30°  E. ;  cleavage  dips  the  same. 

27.  Jacob  O.  Pystef1  s  quarry,  one  and  a  half  miles  S.  E. 
of  Bangor,  50x50x20  feet ;  cleavage  30°,  S.  30°  E. 

88.  Two  miles  S.  E.  of  Bangor,  on  the  east  side  of  Mar- 
tin's creek,  on  P.  Pysher's  farm,  is  a  small  cut  50x30x30  ; 
dip  10°  N,  ;  cleavage  30°  S.  ;  slates  all  thin  bedded  ribbon 
slates. 

29.  True  Blue  slate  quarry  (Fig.  6,  p.  548),  on  Martin's 
creek  1  m.  E.  of  Factoryville;  irreg'ular,  averaging  about  150 
X  150x80  ;  at  the  face  the  structure  is  shown  as  in  the  fig- 
ure ;  in  the  cut  the  cleavage  is  25°  S.  parallel  to  the  plane 
of  the  two  axes.     At  the  bottom  of  the  cut  a  quartz  vein 
shows  one  foot  thick  dipping  25°  S.,  spoiling  the  cleavage 
for  a  short  distance  on  each  side  of  it.     On  the  south-east 
corner  of  the  quarry  a  few  small  quartz  veins  show.     The 
slates  are  all  thin  bedded  ;  have  a  good  metallic  ring,  but 
those  that  have  been  exposed  on  the  dump  show  signs  of 
bleaching.     The  quarry  not  being  worked  in  1882. 

Lower  Mt.  Bethel  township. 

30.  On   Little  Martin's  CreeJc^  half   a   mile  above  the 
school-house,  ribbon  slates  show  dipping  70°  N..  with  a 


SLATE  IN  NORTHAMPTON  AND  LEHIGH  COUNTIES.        593 

cleavage  of  25°  south.  A  quarter  of  a  mile  below  the  school- 
house  ribbon  slates  show  with  a  flat  dip  and  cleavage  of  25°, 
S.  10°  E. 

32.  In  the  bottom  of  a  small  hollow  half  a  mile  north- 
west of  Martin's  Creek  Post  Office,  there  is  a  small  aban- 
doned quarry  of  ribbon  slate  ;  dip  45°,  N.  20°  W.  ;  cleavage 
S.  20°  E.* 

Plainfield  township. 

3f.  Hull's  quarry,  A.  &  O.  T.  Hull,  1  m.  N.E.  of  Pen  Ar- 
gyl;  250xl50x-qO;  15' loose  slate  on  top;  dip  at  surface 
68°,  S.  10°  E.  but  steeper  in  the  lower  part  of  the  quarry  ; 
cleavage  15°,  S.  10°  E.  ;  two  largest  beds  10  and  7  feet  thick  ; 
blocks  come  out  even  and  split  and  sculp  well ;  not  as  much 
waste  as  in  the  average  run  of  quarries. 

38  Pennsylvania  quarry,  at  north  end  of  Pen  Argyl ;  250 
X200  feet ;  dip  at  N.  end  55°,  N.3<)°  W.,  gradually  flattening 
southward  ;  cleavage  25°,  S.  30°  E.  Seventy  feet  from  the 
north  end  is  a  20  foot  bed  ;  some  distance  below  this  a  6  foot 
bed  ;  rest  of  the  beds  smaller  ;  most  of  the  ribbons  tight. 

39.  Jory  quarry,  N.  A.  Jory  &Co.,  400x200x80  ;  worked 
in  the  center  of  a  synclinal;  dip  slight  in  center  of  axis  ; 
plane  of  axis  vertical ;  cleavage  horizontal.^ 

*Just  above  the  mouth  of  Martin's  creek  the  contact  of  the  slates  and 
limestones  shows.  The  slates  foi  half  a  mile  up  the  creek  are  seen  dipping 
slightly  towards  the  north,  and  are  very  much  contorted.  The  cleavage  ia 
Hat,  the  beds  are  small  but  not  ribbon  slate.  Just  east  of  where  the  road. 
from  Martin's  creek  crosses  Mud  run,  vertical  black  slates  show  with  a 
horizontal  clearatje.  The  largest  bed  is  two  feet  thick.  On  the  road  lead- 
ing down  Mud  run  between  Hutchinson  <fe  Kahler's  an  anticlinal  shows  in 
the  slates.  The  slates  are  ribbon  slates.  In  the  samecut  two  reins  of  quartz 
show  dipping  steeply  to  the  south.  Just  west  of  Hutchinson's  ribbon  slates 
show  dipping  N.  20°  W.  Cleavage  40°,  S.  20°  E. 

The  contact  of  II  and  III  enters  Forks  township  a  few  hundred  yards 
south  of  its  north-east  corner,  and  passes  through  the  township  in  a  south- 
westerly direction,  crossing  Bushkill  creek  into  Palmer  township  west  of 
the  Lutheran  church  at  Churchville.  In  Palmer  township  the  junction 
line  is  not  well  shown.  The  area  covered  by  slates  is  a  strip  across  the  nor  th- 
em portion  of  the  township  half  a  mile  wide. 

*This  is  the  only  quarry  in  which  the  cleavage  can  be  seen  at  right  angles, 
or  any  considerable  angle  to  the  plane  of  the  axis.  The  beds  worked  are 
not  large,  but  the  cleavage  making  such  a  large  angle  with  the  bedding, 
large  blocks  can  be  taken  out  They  were  making  about  25  squares  a  day 
with  4  shanties  at  the  time  of  visiting  the  quarry.  There  are  two  spar  der- 
ricks worked  by  horse  power. 
38 


5&4  GEOLOGICAL  SURVEY    OF  PENNSYLVANIA. 

40.  Jackson's  quarry  ;  300x200  by  about  100  feet  deep  ; 
ttoo  cable  derricks,  run  by  two  double-cylinder  engines  ;  4 
shanties  averaging  about  4  squares  a  day  to  a  shanty  ;  slates 
come  out  in  good  sized  blocks,  some  of  them  20  feet  long  ; 
split  and  sculp  well  and  fracture  rather  well. 

41.  .Robinson  quarry,  Stephen  &  Jackson,  400x200x80  ; 
dip  28°  south  ;  cleavage  flat  ;  beds  25,  16  and  12  feet  long 
along  the  cleavage ;    one  cable  derrick  and  several  spar 
derricks,  run  by  horse  power;    16  shanties  in  operation 
(1882). 

4®.  West  Washington  quarry,  Fulmer  and  Jackson, 
150x75  feet  and  50  feet  deep  ;  25  feet  of  loose  material  on 
top  ;  same  bed  as  at  the  Robinson  and  Jackson  quarries  ; 
best  bed  is  the  gray  bed,  which  is  also  worked  in  the  Jack- 
son ;  dip  48°  south  ;  cleavage  flat.  * 

43.  H.  Young 's far in,  \\  miles  west  of  Blue  Mountain 
Post  Office  ;  a  small  cut  in  the  hill  side  showing  slate  beds, 
the  largest  of  which  is  2  feet  thick ;  dip  15°,  N.  20°  W. 
cleavage  15°,  S.  20°  E. 

44-  Delabole  quarry,  of  Factory ville  ;  150x100;  dip  80°, 
S.  30°  E.  ;  cleavage  25°,  S.  30°  E.  ;  all  thin  bedded  sfates  ; 
beds  large  between  the  loose  ribbons. 

46.  Pine  Grove  quarry,  Edleman  &  Co.,  200x150x130; 
dip  60°  N.  ;  cleavage  flat  ;  slates  all  thin  bedded  ;  make 
besides  roofing  slate,  flagging  and  fence  posts. 

47.  White  Oak  quarry,  T.  Reed  &  Co.,  150x100x100  ;  dip 
20°  N.  ;  cleavage  10°,  S.  45°  W.  ;  joints  vertical,  and  in  one 
part  of  the  quarry  80  feet  from  joint  to  joint ;  slates  all 
thin  bedded  ;  average  about  3,000  squares  of  slate  a  year. 

48.  Samuel  Seams'  quarry,  1  m.   ^N".  by  E.   of  Belfast ; 
200x200x80  feet ;  dip  20°  to  the  north;  cleavage  flat  or 
slightly  to  the  west ;  slates  all  thin  bedded  ;  largest  bed  30 
feet  between  loose  ribbons  ;  other  beds  worked  are  16,  12 
and  4  feet  between  loose  ribbons  ;  make  about  4, 800  squares 

*  At  S.  end  the  top  bed  is  10'-thick,  then  follow  downward  6  beds  in  2  feet, 
there  is  a  2  ,  3",  and  a  7"  bed  and  1'  8",  2',  3",  1'  6",  1'  3",  7",  1'  6",  10",  9",  1' 
7",  2",  1'  10",  9",  15'  6",  6',  3',  3  beds  in  6",  3',  7",  6",  2',  9",  1'  3",  4",  1'  2", 
11'',  3",  1'  1",  1'  5",  6",  10'  2"  the  gray  bed,  30  feet  of  beds  2  feet  and  under  in 
thickness,  4'.  The  10  foot  bed,  at  the  top  of  the  quarry  has  2  feet  of  rook  on 
top,  a  dark  fine-grained  sandstone.  The  gray  bed  has  also  rock  on  top. 


SLATE  IN  NORTHAMPTON  AND  LEMIGH  COUNTIES.       595 

a  year  ;  also  flagging  and  fence  posts  ;  worked 'by  two  cable 
derricks  run  by  one  engine. 

49.  Young,  Duck  &  Co.' s  quarry,  1  mile  W.  of  Kessler's 
Post  Office  ;  fall  of  water  ;  dip  20°  north  ;  cleavage  flat ; 
slates  all  thin  bedded.* 

50.  James  Deck's  quarry,  100x100  feet,  full  of  water; 
dip  15°  north  ;  cleavage  flat ;  slates  all  thin  bedded. 

52  Davidson's  quarry,  I  m.  S.  W.  of  Kessler's  Post 
Office,  150x100,  full  of  water  ;  abandoned  ;  dip  60°,  N.  20° 
W.  ;  cleavage  20°,  S.  20°  E.  ;  slates  all  thin  bedded. 

53.  Belfast  quarry,  %  m.  S.  of  Davidson's  quarry,  150 x 
75  ;  full  of  water  ;  10'  stripping  ;  slates  thin  bedded  ;  dip  20°, 
N.  20°  W.  ;  cleavage  20°,  S.  20°  E. 

Bushkill  township. 

60.  Hughes  Bros,  quarry,  f  m.  S.  E.  of  Jacobsburg  ;  100 x 
150x60  ;  average  dip  70°  ;  cleavage  20°  S.  ;  slates  all  thin 
bedded  ;  longest  distance  between  loose  ribbons  25  feet ; 
makes  about  1,500  squares  a  year,  and  have  made  as  high 
as  8  squares  a  day  to  a  splitter,  but  4  a  day  is  a  good  aver- 
age ;  25  feet  from  the  top  of  the  quarry  &  fault  shows  dip- 
ping 20°  to  the  south  ;  it  has  moved  the  slate  on  top  3  feet 
to  the  south.f 

62  Henry's  quarry ;  150x200x70  ;  dip  20°,  S.  50°  E.  ; 
cleavage  13°,  S.  40°  E.  ;  slates  thin  bedded  ;  joints  vertical 
and  in  different  directions  ;  main  joints  parallel  to  strike  ; 
some  few  quartz  veins  /  color  of  the  different  beds  of  slate 
almost  identical  ;  planes  of  loose  cleavage  from  5  to  7  to  12 
feet  apart ;  two  cable  derricks,  run  by  one  engine  ;  make 
about  1,800  squares  a  year. 

65.  St.  Nicholas  quarry,  James  Titas,  township  line  1£ 

*Two  miles  northeast  of  Kessler's  Post  Office,  thin  bedded  slates  show 
dipping  20°  noith  ;  cleavage  40°  south. 

fOu  M.  Train's  farm  south  of  his  house  there  is  a  shaft  sunk  for  slates,  15 
feet  deep.  The  dip  is  doubtful  but  looks  50°  S.  Cleavage  is  50°.  The  shaft 
just  enters  the  solid  slate.  Just  west  of  Jacobsburg  a  thin  bedded  slate 
shows  with  a  flat  dip,  and  cleavage  30°  south.  One  quarter  of  a  mile  south 
of  Jacobsburg  the  cleavage  is  10°  south.  Where  the  Bushkill  creek  leaves 
the  township  the  thin  bedded  slates  show  with  a  vertical  dip  and  flat 
cleavage. 


596  GEOLOGICAL   SURVEY    OF   PENNSYLVANIA. 

miles  west  of  Cleartield  ;  100x100x30  feet ;  dip  15°,  S.  40° 
E.  ;  cleavage  55°,  S.  40°  E.  ;  full  of  water  in  1882. 

66.  Douglass  slate  quarry,  on  north  side  of  Bushkill 
creek,  west  of  Douglasville  ;  300x150;  full  of  water. 

69.  1£  miles  west  of  Cherry  Hill  in  front  of  J.  Heyer's 
house  two  small  openings  50x75  and  20x20;  slates  thin 
bedded  and  on  the  dump  have  bleached  and  rusted  badly. 
A  few  hundred  yards  further  down  the  run  there  is  an 
abandoned  quarry  150x100  feet  full  of  water  ;  dip  35°,  S. 
40°  E.  ;  cleavage  15°,  S.  40°  E.  ;  slates  thin  bedded. 

71.  Daniel's  quarry,  full  of  water,  250x150  feet ;  slates 
thin  bedded  ;  dip  flat ;  cleavage  20°  S.  Some  of  the  slates 
on  the  pile  Jiave  about  10  beds  in  them.* 

Upper  Nazareth  township. 

At  the  end  of  the  borough  of  Nazareth  the  slates  are  flat 
and  rolling.  One  mile  west  of  Nazareth,  on  the  Bath  road, 
black  slates  show  with  a  horizontal  dip.  A  high  slate  ridge 
rises  1,000  feet  north  of  the  road,  but  the  slates  extend  half  a 
mile  south.  This  is  a  good  place  to  study  the  Utica  black 
slate  for  mat  ion  III  a,  and  its  passage  upward  into  the 
Hudson  Ricer  formation  III  />. 

Moore  township. 

16.  Daniel  Beef  s  quarry,  on  the  east  side  of  the  town- 
ship, half  a  mile  south  of  the  railroad  :  150x100;  full  of 
water  ;  on  the  same  beds  as  the  St.  Nicholas  ;  dip  10°  S. 
40°  E.  ;  cleavage  65°,  S.  40°  E. 

*There  are  about  50  squares  on  the  pile,  most  of  them  have  iron  pyrites 
in  them  at  the  junction  of  the  ribbons;  the  slates  on  the  end  of  the  pile 
have  changed  color.  Some  of  them  also  have  thin  veins  of  quartz  in  them. 
On  the  east  side  of  the  creek  100  feet  north  of  the  Daniel's  quarry,  the  thin 
bedded  slates  are  seen  turning  to  the  north,  the  dip  being  20°  north.  The 
•cleavage  is  20°  south.  500  feet  further  north  the  dip  is  20°  to  the  east ;  50 
feet  further  north  it  is  10°  north.  800  feet  north  of  this  there  is  a  small  aban- 
doned cut  60X60  feet  showing  the  slates  flat.  Half  a  mile  north  of  Daniel's 
quarry  a  small  opening  10  feet  deep  in  thin  bedded  slate  shows,  with  a  dip 
•of  10°  to  the  south  and  a  cleavage  of  15°  south.  Half  a  mile  north  of  the 
above  there  is  another  abandoned  quarry  50x75  feet,  full  of  water.  The 
slates  are  all  thin  bedded,  bleached  and  iron  stained.  The  dip  is  flat  and 
cleavage  20°  south. 


SLATE  IN  NORTHAMPTON  AND  LKHIGH  COUNTIES.        597 

79.  Chapman  quarry;  500x300x139;  has  6  cable  der- 
ricks run  by  independent  engines  ;  30  shanties  in  opera- 
tion ;  splitters  make  from  2  to  6  squares  a  day,  averaging 
about  4 ;  hoisting  apparatus  very  complete ;  can  hoist  a 
stone  of  two  tons  150'  vertical  and  300'  horizontal'in  about 
2  minutes  ;  large  factory  for  making  and  planing  slabs  and 
other  sawed  material  ;  with  3  diamond  saws,  4  planers,  1 
jig  saw  and  1  smoothing  table  ;  diamond  saws  cut  by  re- 
ciprocating motion,  at  the  rate  of  an  inch  in  5  minutes, 
50  stroke  a  minute.  The  slates  are  all  thin  bedded,  split 
well  and  are  tough  ;  the  blocks  come'out  of  the  quarry  in 
large  even  pieces,  some  of  them  20  feet  long ;  sculp  and 
fracture  well.* 

82.  ^Empire  quarry,  on  the  Manocacy  creek,  1  m.   E.   of 
Chapman's;  100x100;  full  of  water;  cleavage  10°  south; 
slates  thin  bedded  ;  iron  pyrites  in  some  of  them  ;  also  a 
few  small  quartz  veins  running  through  the  slates. 

83.  Richard  Moser*  s  quarry,  300  yards  up  the  creek  from 
the  Empire  ;  full  of  water  ;  cleavage  20°  south  ;  slates  thin 
bedded  ;  weather  to  a  slightly  different  color  ;  some  show 
iron  pyrites. 

84.  MaucJi  Chunk  quarry,  at  Chapman's  Station;  200 x 
150,  full  of  water ;  dip  vertical  ;  cleavage  22°,  S.  40°  E.  ; 

slates  tHin  bedded. 
j^ 

So.  Bethlehem  quarry  \  200x150x80;  dip  on  the  surf  ace 
vertical,  then  south  a  short  distance  and  again  vertical  ; 
cleavage  10°  south  ;  slates  all  thin  bedded  ;  distances  be- 
tween the  loose  ribbons  along  the  cleavage  of  the  workable 
beds  are  7',  7',  3£',  9',  3'  and  3' ;  one  cable  derrick  run  by 
a  15  horse-power  oscillating  engine  ;  six  shanties  in  opera- 
tion (1882).  On  the  south  side  of  the  quarry  t'ley  had  to 
go  down  60  feet  before  getting  to  good  slate.  On  the  north 
they  went  down  only  20  feet.  There  is  a  quartz  vein  dip- 
ping to  the  south  through  the  quarry  20  feet  from  the  stir- 


*  A  few  hundred  yards  east  of  Chapman's  there  is  an  abandoned  quarry 
250X250.  East  of  Chapman's,  across  the  creek,  another  50X50  full  of  water  ; 
cleavage  20°  E.  ;  slates  thin  bedded. 


598  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

face  on  the  north  side  and  60  feet  on  the  south.     The  slate 
above  the  vein  has  not  a  good  cleavage.* 

88.  Thomas  Ryan's  quarry,   100x50x40;   slates  thin 
bedded  ;  joints  vertical ;  cleavage  horizontal ;  dip  towards 
the  south  averaging  about  60°.     Some  few  slates  have  iron 
pyrites  in  them. 

89.  Jacob  Flin'rf s  abandoned  quarry,  1,000  feet  north- 
west of  Ryan's  quarry  ;  100x40x30;  dip  30°,  N.  ;  cleavage 
flat.     Quarry  said  to  have  been  abandoned  because  the  slates 
were  twisted. 

90.  Abandoned  quarry,  1,000  feet  north  of  Chapman's, 
60x60,  full  of   water;  dip  vertical;  cleavage  S.   10°   E.  ; 
slates  all  thin  bedded. — 400  feet  west  of  this  another  quarry 
100x40  full  of  water,  with  vertical  dip  and  cleavage  of  10°, 
S.  20°  E. 

91.  Abandoned  quarry,  1  m.  W.  of  Chapman's,  100x50, 
full  of  water ;  slates  thin  bedded. 

92.  Helmari's  quarry,  1%  miles  S.  W.  of  Chapman's  ; 
100x100  feet,  full  of  water;  dip  45°  south  ;  cleavage  flat ; 
joints  vertical ;  slates  thin   bedded ;    those  on  the  dump 
bleached  and  iron  stained. 

93.  McKee's  quarry,  600  feet  north  of  Helman's  ;  100  x 
100,  full  of  water  ;  dip  22°,  S.  25°  E.  ;  cleavage  15°,  S.  25° 
E.  ;  joints  vertical,  running  east  and  west  and  north  and 
south  ;  slates  thin  bedded,  f 

96.  Northampton  quarry,  1  m.  S.  W.  of  Chapman's  ; 
two,  both  full  of  water;  the  southern  one  150x150,  the 
other  about  the  same  size  ;  separated  by  about  25  feet  of 
slate  ;  15  feet  from  the  top  a  heavy  vein  of  quartz  dipping 
slightly  to  the  south ;  cleavage  20°,  S.  40°  E.  ;  slates  all 
thin  bedded  ;  those  left  on  the  dump  appear  very  rough  and 
thick ;  some  of  them  have  iron  pyrites  in  them,  and  they 
have  changed  color.  (See  page  548  above.) 

*  Abandoned  quarry  west  of  the  last  and  300  feet  on  the  strike  from  it  ; 
200'X200' ;  cleavage  10°,  S.  10°  E.  ;  joint  vertical.  A  quartz  rein  shows  in 
this  quarry  as  in  the  Bethlehem.  200  feet  north  of  this  there  is  another 
abandoned  quarry  100X100  full  of  water. 

fOn  the  ridge  a  mile  east  of  the  Emanuel  church,  loose  thin  bedded  sand- 
stone covers  the  surface  of  the  ground.  300  yards  north  of  Emanuel  church 
slate  dips  90°  to  the  north  with  a  cleavage  of  45°  south. 


SLATE  IN  NORTHAMPTON  AND  LEHIGH  COUNTIES.       599 

97.  Abandoned  quarry  (Fig.  7),  \  in.  S.  of  Chapman's, 
150x150,  full  of  water;  slates  thin  bedded;  vertical  dip. 
The  horizontal  section  in  the  figure  shows  the  contortions 
in  the  strike  of  the  rock  at  the  northwest  corner  of  the 
quarry. 

East  Allen  township. 

98.  Chester  county  quarry  is  200x250x130  feet  deep. 
The  slates  dip  20°,  S.  40°  W,     Cleavage  horizontal.     At  10 
to  40  feet  from  the  top  of  the  cut,  veins  of  quartz  show 
parallel  to  the  bed  plates.     The  slates  are  all  thin  bedded 
and  the  beds  differ  slightly  in  color.     Some  few  of   the 
slates  have  a  small  amount  of  iron  pyrites  in  them.     The 
blocks  coming  out  of  the  quarry  are  large  and  even  in  size. 
Some  of  them  are  20  feet  long,  4  feet  wide  and  2  feet  thick, 
but  do  not  seem  to  split  well.     There  is  a  little  water  in  the 
quarry.  It  is  worked  by  two  cable  derricks,  run  by  one  forty- 
horse  power  engine.     At  the  corner  of  the  road,  just  north 
of  the  quarry,  there  is  an  abandoned  quarry  full  of  water.* 

100.  A.  Koch1  s  quarry,  on  Catasauqua  creek,  3  miles  W. 
of  Bath  ;  200x100  ;  full  of  water ;  dip  15°  to  N.  ;  cleavage 
5°  to  S.  ;  slates  thin  bedded  ;  some  iron  pyrites. 

*  The  contact  of  slate  and  limestone  enters  the  township  from  Upper  Naz- 
areth east  of  Bath,  takes  a  westerly  direction,  crossing  the  railroad  half  a 
mile  south  of  Bath,  continues  on  to  the  south-west  for  a  mile,  turns  to  the 
south  for  J  of  a  mile,  then  turning  to  the  west  passes  through  Jacksonville 
and  then  along  to  the  west,  keeping  south  of  the  road  leading  west  from 
Jacksonville.  There  are  three  outlying  patches  of  limestone  in  the  north- 
western part  of  the  township  shown  on  the  map.  They  are  probablybrought 
to  the  surface  by  the  anticlinal  which  enters  the  slate  south-west  of  Bath. 
Their  shape  cannot  be  accurately  defined  owing  to  the  surface  being  covered 
with  loose  slate.  A  limestone  quarry,  1,000  feet  west  of  the  Chester  slate 
quarry.  The  dip  of  the  limestone  is  20°  to  the  west.  On  top  of  the  quarry 
there  is  a  body  of  slate  which  is  non-conformable  to  the  limestone.  The 
slate  is  somewhat  broken  and  has  probably  fallen  down  on  the  eroded  lime- 
stone. One  quarter  of  a  mile  S.  of  Koch's  quarry  the  limestone  crops  out, 
dip  flat,  with  loose  slate  on  top  of  it.  1,000  feet  south  of  this  more  limestone 
outcrops,  and  about  50  feet  lower  the  slates  show.  There  is  a  small  cut  in 
the  bottom  of  the  hollow  at  this  place,  hut  it  is  full  of  water,  and  nothing 
could  be  seen.  At  the  saw  mill  dark  blue,  thin-bedded  limestone  crops  out 
with  a  dip  of  30°  to  the  S.  30°  E.  There  is  a  small  amount  of  graphite  on 
the  bed  plates.  Just  south  of  this  outcrop  of  limestone,  gray  slates  show, 
dipping  30°  to  the  north,  and  at  the  road  leading  west  from  Jacksonville  is 
gray  cement  stone  dipping  35°  to  the  south. 


600  GEOLOGICAL    SURVEY    OF    PENNSYLVANIA. 

Allen  township. 

106.  Abandoned  gnarry,  lies  a  few  hundred  yards  east  of 
the  railroad  near  S.  B.  Hoffman's  house,  having  about  5, 000 
cubic  yards  taken  out  of  it  ;  dip  10°,  S.  10°  E.  ;  cleavage 
parallel  to  bedding  ;  a  few  quartz  veins. 

107.  Abandoned  quarry,  If  miles  north  of  Siegfried's 
bridge,  on  the  Central  Railroad  of  New  Jersey,  75x50,  full 
of  water  ;  dip  flat ;  thin  bedded  slates.* 

Lehigli  township. 

108.  S.  Reple 's  quarry,  across  the  road  from  the  hotel 
at  Rockville,  100x200,  full  of  water.     For  500  feet  north 
along  the  foot  of  the  hill  there  are  several  small  openings 
showing  the  slates  flat  and  dipping  20°,  S.  10°  E.  ;  cleavage 
65°,  S.  10°  E.  ;  main  opening,  slates  flat ;   one  bed  7  feet 
thick,  f 

111.  Old  Harper's  now  Henry's  quarry,  %  m.  S.  E.  of 
Danielsville  ;  dip  steep  N.  45°  W.  ;  cleavage  45°,  S.  10°  E.  ; 
beds  small,  with  small  tight  ribbons4 

11%.  J.  Henry's  quarry  (Fig.  8),  £  m.  S.  of  Harper's 
quarry;  200x150x30;  regular  synclinal  axis;  cleavage 
at  center  and  north  side  vertical,  but  on  south  side  about 
60°  south. 

113.  Eagle  slate  quarry,  F.  M.  Hower,  i  m.  S.  of  Har- 
per's;  two  openings  in  a  line  100x200x60,  separated  by 
50  feet  of  rock  ;  dip  80°,  S.  10°  E.  ;  cleavage  60°,  S.  10°  E.  ; 

*  South  of  Kreidersville  the  slates  dip  20°  S.  and  the  cleavage  20°  S.  On 
R.  R.  at  N.  W.  corner  of  the  township  the  slates  have  a  slight  dip  to  the  south, 
averaging  about  5°  with  rolls  and  twists  and  a  few  small  vertical  faults ; 
cleavage  indistinct,  about  40°  to  the  south  ;  at  center  and  north  end  of  cut 
slates  flat  with  rolls  and  twists  ;  everything  contorted. 

f  Three  quarters  of  a  mile  south  of  Rockville  outcrop  of  large  bed  of 
apparently  good  roofing  slate  ;  cleavage  60°  south.  East  of  Harper's  grist- 
mill outcrop  of  small  slate  beds;  dip  20°,  S.  50°  W.  ;  cleavage  60°  S. 

J  The  cleavage  in  this  quarry  is  not  parallel  to  the  strike,  but  the  strike  of 
the  rocks  is  not  parallel  to  the  mountain  ;  if  it  were  continued  it  would  strike 
the  mountain  at  from  a  mile  to  two  miles  and  a  half.  The  slates  look  good, 
some  of  them  are  of  a  different  color,  separated  by  a  wavy  line  but  no  rib- 
bon.— 200'  S.  of  the  quarry  is  an  old  opening  now  being  filled  up. 


NO.   III.       ROOFING    SLATE   BELT.  601 

no  large  beds  ;  cleavage  nearly  parallel  with  bedding ; 
blocks  of  20  to  30  feet  in  length  sometimes  obtained.  They 
make  about  80  squares  a  day  and  also  a  few  school  slates. 

114.  McChunk  and  National  quarries,  i  m.   E.   of  the 
Eagle  quarry  and  close  together  ;  one  100  x  150,  the  other 
250x250,  both  full  of  water.     In  the  southern  one  the  rocks 
appear  to  dip  80°  S.,  the  cleavage  40°  S.  ;  largest  bed  not 
over  5  feet,  but  only  50  of  the  250  feet  in  the  quarry  is  ex- 
posed ;  slates  left  on  the  pile  thick  and  have  a  poor  ring. 

115.  Uplinqer    &    Griffith'1  s   quarry  and    Uplinger    & 
Henry's  quarry  (Fig.  9) ;  two  quarries  150  feet  apart ;  500 
feet  south  of  the  Eagle  quarry  is   Uplinger  &  Harper's 
quarry  ;  dip  80°  N.  ;  quarry  full  of  water.     150  feet  south, 
at  the  north  end  of  Uplinger  &  Griffiths'  quarry,  slates  lie 
flat ;  for  800  feet  more  an  occasional  outcrop  shows  a  flat 
dip  ;   at  the  south  end  of  the  quarry  (where  they  were 
working  in  1882)  a  synclinal  axis.     None  of  the  beds  large  ; 
slates  look  good  and  are  darker  than  at  most  of  the  other 
quarries. 

116.  Continental  quarry,   \\  miles  S.  of  Daniels ville  ; 
full  of  water  ;  200'  square  ;  dip  80°  S.  ;  cleavage  45°   S.  ; 
one  bed  10  feet  thick.* 

118.  Col.  B.  Mauref  s  slate  factory  is  one  mile  north  of 
Poplar  Grove,  where  they  make  about  2,000  school  slates  a 
day. 

119.  Newcille  Slate  Co.' s  quarry,   1  m.  N.   of   Poplar 
Grove  on  the  south  bank  of  Bertsch  creek;  75x125x90 
deep  ;  dip  42°,  S.  10°  E.  ;  cleavage  75°,  S.  10°  E.  ;  ribbons 
tight ;  some  jet  black;  bottom  bed  15  feet ;  then  4  feet  of 
small  beds  ;  one  bed  15  feet  thick  ;  25  feet  of  small  beds, 
and  on  top  one  bed  10  feet  thick. 

120.  New  York  and  Pennsylvania  quarry,  li  m.  IS",  of 
Poplar  Grove  ;  full  of  water ;  reported  cleavage  imperfect 
and  slate  rocky. 

*  An  abandoned  quarry,  |  of  a  mile  east  of  Danielsville  and  200  feet  north 
of  the  strike  of  the  Continental  quarry,  shows  a  flat  synclinal,  with  the 
cleavage  dipping  60°  to  the  south. 


602  GEOLOGICAL   SURVEY    OF   PENNSYLVANIA. 

121.  Kestef s  Meadow  quarry,  leased  by  John  Pauls  and 
Peters;    150x100x60;  10  to  15  feet  loose  slate   on   top; 
largest  bed  24  feet ;  blocks  come  out  in  large,  even  pieces  ; 
split  well  and  the  slate  looks  good.     In  1882,  working  on 
the  large  bed,  on  the  south  side  of  the  synclinal  axis ; 
cleavage  about  45°  S. 

122.  Doddridge  quarry,  leased  by  Joseph  Roberts;  500 
yards  north  of   the  Kester  Meadow  quarry ;   just  (1882) 
started;  cut  down  30 feet,  showing  one  bed  11  feet  thick, 
with  a  few  small  beds  on  top  ;  dip  70°,  S.  10°  E.  ;  cleavage 
65°,  S.  10°  E. 

123.  J.  Remley 's  quarry,  1  m.  E.  of  Walnut  Port,  small, 
15  feet  deep,  full  of  water  ;  dip  60°,  S.  10°  E.  j  cleavage  50°, 
S.  10°  E  ;  two  large  beds  reported  in  this  quarry,  the  largest 
one  10  feet  thick  (probably  10  feet  along  the  cleavage) ; 
slates  on  the  dump  look  good. 

12  4.  HeiribacKs  quarry  (Fig.  10),  H  m.  N.  E.  of  Wal- 
nut Port,  leased  by  Caskie  &  Emack.  The  section  of  the 
eastern  face  of  the  quarry  shown  in  Fig.  10,  gives  the  struc- 
ture. The  quarry  is  100x200x60  ;  main  cut  originally  150  feet 
deep,  now  partially  filled  by  waste.  It  is  now  (1882)  worked 
by  two  tunnels,  one  driven  east  and  the  other  west.  The 
main  opening  shows  the  rock  about  vertical,  but  Mr.  Caskie 
says  that  in  the  bottom  they  bent  towards  the  north. 
Joints  mostly  horizontal  and  quite  persistent,  but  some  dis- 
tance apart,  allowing  large  blocks  to  be  taken  out.  In  each 
of  the  tunnels  there  is  a  joint  at  thereof.  The  largest  beds 
are  from  10  to  15  feet  thick,  making  a  total  (along  the  cleav- 
age) of  about  25  feet.  The  whole  150  feet  of  the  breadth 
of  the  quarry  is  used  for  making  roofing  slate.  There  is  a 
factory  at  the  quarry  for  making  school  slate  with  a  capac- 
ity of  10,000  cases  a  year. 

126.  Owen  Williams  &  Co.'1  s  quarry,  J  m.  W.  of  Hem- 
backs  ;  200X100X80  ;  60  feet  of  slate,  used  for  roofing  and 
school  slates  ;  largest  bed  8  feet  thick  ;  other  beds  6',  3' and 
4'.  The  note  (1882)  adds  :  100  feet  west  of  this  quarry  Mr. 
David  Williams  has  opened  a  quarry.  He  has  only  the 


NO.  III.   ROOFING  SLATE  BELT.  603 

gravel  stripped  off,  which  is  about  20  feet  deep.  The  beds 
he  expects  to  strike  are  the  same  as  in  Owen  Williams  & 
Co.'s  quarry. 

127.  Williams  &  Jones'  quarry,  just  west  of  Owen  Wil- 
liams' quarry;  200x100x90;  dip  in  the  bottom  vertical; 
at  the  south  side  near  the  surface  a  roll  in  the  rocks  ;  clea- 
vage 60°,  15  S.  E.    In  this  quarry  there  is  a  bed  of  slate  from 
which  they  make  slate  pencils. 

128.  Abandoned  quarry  just  N.   of  Walnut  Port,  200 x 
200  feet,  full  of  water.* 

135.  Beach,  Barge  &  Co.'s  quarry,  1  m.  below  Treich- 
ler's,  in  the  hill  side  east  of  the  railroad,  is  50  feet  deep  at 
its  face  ;  dip  15°,  S.  10°  E.  ;  cleavage  the  same  ;  slates  thin 
bedded,  dark  blue  with  a  good  ring.f 

*On  the  railroad  above  the  dam,  the  dip  of  the  slates  is  30°,  S.  10°  E. ; 
cleavage  60°,  S.  10°  E.  100  feet  further  north  the  dip  is  25°,  N.  20°  W.  ; 
cleavage  60°,  S.  10°  E.  Just  above  this  an  anticlinal  shows  with  aflat  clea- 
vage ;  then  100  feet  further  north  the  slates  dip  vertically.  A  few  hundred 
yards  south  of  the  wagon  bridge  the  slates  dip  50°  to  the  south.  A  short 
distance  from  where  the  wagon  road  goes  under  the  railroad  a  massive  gray 
conglomerate  (dipping  30°,  N,  30°  W.)  is  made  up  of  white  and  black  pebbles 
averaging  one  inch  in  diameter ;  also  tine  grained  gray  sandstones.  The 
junction  of  III  and  IV is  not  visible ;  but  the  slates  50  feet  below  are  seen 
gradually  turning  into  sandstone.  A  hundred  feet  N.  of  the  road  crossing 
is  the  last  place  the  slates  are  seen,  50  feet  below  the  sandstone  of  IV. 
Further  south,  250  feet,  an  anticlinal  in  the  slates  appears  in  the  side  of  the 
road.  The  axis  of  the  anticlinal  is  about  vertical,  and  the  cleavage  is  par- 
allel to  it  Two-thirds  of  a  mile  south  of  Walnut  Port  the  slates  dip  75° 
south.  There  are  some  small  beds  of  interbedded  sandstone  at  the  same 
place. 

fOn  the  railroad,  at  the  township  line  there  are  three  peculiar  curves 
showing  in  the  slates.  The  cleavage  is  parallel  to  the  axis  of  these  curves. 
In  the  first  one  the  axis  dips  5°  to  the  south.  500  feet  north  and  under  the 
above  there  is  another  flat  turn  with  the  axis  horizontal,  then  300  feet  further 
north  there  is  a  flat  turn  with  the  axis  dipping  10°  to  the  south. 


604  GEOLOGICAL   SURVEY    OF   PENNSYLVANIA. 

Quarries  in  Lehigh  county. 
Washington  township. 

140.  Abandoned  quarry,  1  m.  N.  of  Slatington  25x100, 
a  side  hill  cut  25  feet  deep  ;  dip  25°  to  the  north  ;  cleavage 
60°  to  the  south.* 

146.  Captain  D.  D.  Jones'  new  quarry,  on  Welch  run 
k  m.  N.  of  Slatington  ;  (1882) ;  dip  10°  S.  and  pitch  12°  W. 
with  cleavage  vertical;  big  bed  of  slate  .outcrops  several 
hundred  feet  to  the  east,  30'  thick  ;  twenty  feet  above  big 
bed  another  7£' ;  good  ring,  dark  color,  even  cleavage. 

14-7.  Welchtown  quarry,  John  T.  Robinson  &  Co. ;  opened 
in  1844  ;  two  large  beds,  one  27  feet  along  the  cleavage,  and 
another  on  top  18  feet,  separated  by  25  feet  of  smaller  beds  ; 
in  1882  making  8  squares  a  day  ;  worked  by  a  tunnel  on  the 
27  foot  bed. 

llfi.  Williams'  railroad  quarry,  a  few  hundred  yards 
north  of  the  Slatington  depot,  100x100x100  feet  deep. 

149.  Old  Keystone  quarry,  200'  N.  of  the  Williams  RR. 
quarry ;  side  hill   cut  200  feet  square,  60  to  80  feet  deep 
at  the  face  ;  one  large  bed  16  feet,  then  10  feet  of  small 
beds,  then  a  bed  underneath  25  feet ;  dip  30°  to  the  S.  10° 
E.  cleavage  vertical ;   dip  the  same  all  the  way  to  the  Wil- 
liams quarry  ;  150  feet  south  of  the  Williams  quarry  slates 
dip  70°  south,  cleavage  30°  south. 

150.  Tunnel  quarry,  on  Trout  run,  300  yards  from  river  ; 
one  large  bed  back  of  the  tunnel ;  two  smaller  cuts  along 
side  the  tunnel  had  fallen  in. 

152.  Abandoned  quarry,  just  above  the  borough  bridge 
on  the  south  side  of  Trout  run;  side  hill  cut  100x50x40 
feet  at  the  face  ;  dip  32°  S.;  cleavage  64°  S.;  five  to  twenty 

*  At  the  southern  end  of  Slatington  the  slates  in  the  river  are  vertical. — 
200  yards  S.  of  C.  Zellman's  on  the  railroad  fine-grained  sandstone  out- 
crops; dip  20°  to  S.  ;  largest  layers  4  feet  thick  ;  40  feet  of  sandstone  shows. 
50  feet  further  south  a  synclinal  shows  with  the  sandstone  on  the  south  side 
of  it  vertical. — 300  yards  N.  of  Rockdale  slates  dip  45°  to  the  south  ;  cleavage 
parallel. — At  the  water  station  slates  are  flat.  Just  south  of  the  run  the  dip 
is  25°  N.  ;  rocks  slaty  sandstone  and  slate.  Then  for  over  a  quarter  a  mile 
southward  the  slates  are  flat.  They  then  change  gradually  to  a  dip  of  25° 
to  S.  In  the  next  200  yards  the  dip  changes  gradually  to  15°,  N.  45°  W., 
making  a  synclinal  axis  between  these  two  points.  500  yards  further  down 
the  railroad  Ihe  dip  is  20°,  S.  45°  W. 


NO.   III.       ROOFING   SLATE   BELT.  605 

feet  of  loose  slate  at  the  surface ;  beds  showing  all  under 
four  feet  thick. 

153.  Penlynn  quarry,  150x150x100  feet  deep;  dip  60, 
S.  10°  E;  cleavage  40°,  8. 10°  E.     There  is  a  20  foot  bed  in  the 
quarry.     The  other    beds  are  smaller  and  most    of  them 
workable.     North  of  the  quarry  100  feet  dip  90°;  200  feet 
further  north  flat. 

154.  Old  quarry  No.  1,  500'  N.  40°  E.  from  the  Penlynn 
quarry,  on  the  north  bank  of  Trout  run,  E.  of  Washington 
quarry ;  slates  vertical ;  cleavage  60°  south  ;  two  10  foot 
beds  with  smaller  beds  between. 

155.  Old  quarry  No.  *2  (Fig.  11),  around  the  curve  in  the 
hill  from  quarry  No.  1.     It  shows  a  synclinal  axis  with  the 
plane  of  the  axis  dipping  70°  to  the  south.     The  cleavage 
also  dips  70°  to  the  south  parallel  to  the  plane  of  the  axis. 
It  also  shows  tJie  bed  thickening  as  it  curves  around  the 
axis  from  27  feet  thick  to  35 feet.     Just  after  the  curve  the 
distance  from  where  it  is  27  to  where  it  is  35  feet  is  50 
feet* 

156.  Old  quarry  No.  3,  a  short  distance  down  the  creek 
from  No.  2  ;  one  bed  20  feet  thick  dipping  28°  S. ;  cleavage 
75°  S.     The  quarry  not  worked  in  1882.     All  three  quarries 
belong  to  James  Hess  &  Co. 

156a.  Washington  quarry,  James  Hess  &  Co.,  300 x 
200x75  deep  ;  at  the  south  side  the  slates,  flat  at  the  middle 
of  the  quarry,  turn  sharply  downwards,  the  dip  becoming 
vertical;  cleavage  60°  S. ;  upper  bed  15';  then  twelve  feet  of 
small  beds  ;  lower  bed  12'. 

15Gb.  Blue  Vein  quarry,  200  feet  south  of  the  Wash- 
ington quarry;  on  the  same  beds;  200x  150x75  ;  a  synclinal, 
its  axis  dipping  60°  S. ;  an  anticlinal  between  this  quarry 
and  the  Washington. f  Under  the  twelve  foot  bed  there  is 
a  school-slate  bed.  The  lower  four  feet  of  the  big  bed  has 
rock  in  it.  The  ribbons  when  they  get  under  thirty  or 


*This  is  a  flagrant  proof  of  the  effect  of  the  earth  movement  on  the  whole 
formation  No.  Ill,  in  changing  its  thickness. 

f  This  synclinal  axis  passes  north  of  the  t  enlynu  quarry  through  Slating- 
ton,  and  shows  in  the  Tunnel  quarry.  It  does  not  show  at  the  river,  prob- 
ably owing  to  a  want  of  exposure, 


606  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

forty  feet  of  cover  become  tight.     In  the  south  wall  the 
slates  are  bent. 

157.  Blue  Mountain  quarry  (Fig.  12),  600'  long  east  to 
west,  250'  at  its  widest  part,  120'  deep  ;  surface  loose  for  10 
to  15  feet  down  ;  two  beds  16  and  27,  separated  by  12  feet 
of   smaller  beds ;  started  35  to  40  years   ago  ;  originally 
worked  by  Williams  &  Moser ;    4  spar  derricks  and  1  large 
cable  derrick.     They  are  making  55  squares  a  day  (1882). 

158.  Columbia,  quarry,  N.  side  of  Trout  run  N.  of  the 
Blue  Mountain  quarry  ;  300  feet  long  ;  dip  vertical ;  clea- 
vage 20°,  S.  20°  E.  ;  10  to  30  feet  of  loose  rock  on  top.* 

159.  American  quarry,  No.  1  and  2  (Fig.  13),  W.  of  Co- 
lumbia.    Quarry  No.  1,  250x100  feet;  beds  30',  separated 
by  6  feet  of  small  beds,  one  being  2  feet  thick.    No.  2  shows 
the  section  Fig.  13. 

160.  Girard  quarry,  £  m.  W.  of  Columbia  on  the  N.  side 
of  Trout  run  ;  250x100x50  ;  full  of  water  ;  one  bed  15  feet 
thick, 

161.  Star  Slate  quarry,  300x100x60  ;  dip  70°,  S.  10°  E.; 
cleavage  50°,  S.  10°  E.  ;  two  beds  27'  and  18'  ;  10'  of  clay 
on  top,  and  4'  of  blue  slate  underneath  the  clay. 

162.  Williams,  Owen  &  Jones'  quarry,  40  feet  deep,  100 
feet  square,  in  line  with  Star  quarry  ;  shows  the  slate  turn- 
ing over  towards  the  south  ;  one  derrick,  working  on  the  27- 
foot  bed. 

163.  Franklin  quarry  (Fig.  14).  H  m.  W.  of  Slatington 
depot  and  N.  of  Trout  Run.    (There  are  several  old  openings 
south  of  it  towards  the  Star  quarry.)     On  aflat  synclinal ; 
4  spar  derricks  and  one  cable  derrick  ;  greatest  deph  150'. 

165.  Junction  quarry,  opposite  the  junction  of  the  Slate- 
dale  branch  railroad,  full  of  water,  200x100'  feet  square; 
one  bed  15' ;  the  rest  all  small ;  dip  steep  S.  ;  cleavage  about 
50°  S.     200  feet  north  of  it  a  small  quarry  50x50,  full  of 
water.     On  the  Lehigh  and  Berks  RR.  S.  E.  of  the  junc- 
tion quarry  aflat  synclinal  shows  vertical  cleavage. 

166.  Industrial  slate  quarry,  300  N.   of  the  Junction 

*500  feet  south  of  the  Columbia  is  an  old  abandoned  quarry  ;  the  dip  of 
the  slate  is  70°,  N.  20°.  The  cleavage  50°,  S.  20°  E.— 150'  S.  E.  of  thi%  the 
dip  is  10°  N. 


NO.  III.       ROOFING    SLATE    BELT.  607 

qnarry  ;  working  on  the  20  foot  bed  ;  (1882)  making  about 
15  squares  per  day  ;  dip  vertical  at  the  surface,  curving  to- 
wards the  south  at  the  bottom  of  the  quarry  ;  cleavage 
about  45°,  S.  10°  E. 

167.  Abandoned  quarry  1000'  W.  of  the  Industrial,  full 
of  water,  200x290x40.     There  are  three  other  openings  be- 
sides this,  the  largest  300x100,  all  full  of  water  ;  one  large 
bed  15  feet  thick. 

168.  Abandoned  quarry  1500'  from  the  end  of  Slating- 
ton.     Its  section  is  shown  in  the  section  of  the  Blue  mount- 
ain quarry. 

169.  Blue  Mountain  slate  quarry  (Fig.  15),  250'  N.   of 
east;   200x40x60;   largest  bed  27' ;  dip~60°  N.  ;    cleavage 
about  60°  S.  ;   at   bottom  of  large  bed  cleavage  slightly 
curved  ;  section  of  the  two  quarries  shown  in  Fig.  15. 

170.  Monarch  quarry,  owned  by  Mr.  Hersh,  on  the  south 
side  the  creek  from  the  Blue  Mountain  quarry  shows  the 
same  beds  with  a  dip  of  15°  N.  ;  not  worked  (1882).    Across 
the  road  another  abandoned  quarry  ;  dip  70°  N.  ;  beds  ap- 
parently the  same.     Two  other  quarries  in  the  same  field, 
the  largest  150x150x50'  deep. 

171.  Lock  slate  quarry  (Fig.  16),  ±  m.  W.  of  Slatedale. 
At  the  southeast  end  of  the  quarry  there  is  a  small  open- 
ing 50x50x50  feet  showing  a  bed  15  feet  thick,  dipping 
85°,  N.  10°  W.,  with  a  cleavage  dipping  70°,  S.  10°  E.    The 
main  quarry  is  400'  long.     In  1882  the  work  was  under 
ground  by  means  of  two  slopes  going  down  on  the  large 
bed  ;  cable  derricks  worked  by  one  engine  ;  inclines  three 
feet  apart  ;  structure  shown  in  Fig.  16. 

17%.  Standard  quarry,  i  m.  S.  E.  of  Slatedale,  300x50x 
114'  deep  ;  beds  20',  8'  and  16' ;  3  of  gravel  and  6'  of  loose 
slate  over  the  quarry  ;  the  16-foot  bed  worked  ;  a  large  bed 
at  west  end  did  not  work  well ;  rocks  sculp  and  split  nicely 
and  come  out  of  the  quarry  in  good  sized  blocks.* 

*Grey  slate  shows  in  the  southwest  corner  of  the  township,  dipping  30°, 
S.  20°  W.  The  sandstone  strata  seen  on  the  railroad  one  mile  below  Slat- 
ington  makes  a  high  hill  which  extends  west  more  than  two  miles  back 
fronj  the  river.  No  solid  outcrop  shows,  but  the  ground  is  covered  with 
loose  pieces, 


608  GEOLOGICAL    SURVEY    OF    PENNSYLVANIA. 

JVorfk  WJiitehall  township. 

175.  North  feach  Bottom  Slate  Co.' s  quarry,  2m.  S. 
W.  of  Laury's  Post  Office;  250x200x90  at  the  deepest 
place  ;  slate  beds  horizontal,  with  slight  rolls  ;  cleavage 
about  horizontal ;  joints  vertical,  but  make  different  angles 
with  each  other ;  blocks  20'  square  got  ;  largest  bed  be- 
tween loose  ribbons  8'  thick.  About  30  feet  from  the  sur- 
face there  are  segregated  veins  of  quartz  that  split  the 
cleavage  for  some  distance  around  the  veins.  At  the  top 
of  the  quarry  there  is  a  bed  of  sandy  slate  which  does  not 
split  well,  bat  the  slates  made  are  black,  with  a  good  ring 
and  smooth  surface  ;  the  second  quality  slates  have  a  very 
uneven  surface  and  look  poor.  A  factory  connected  with 
the  quarry  was  engaged  on  an  order  for  flooring  for  the 
Patent  Office  in  Washington,  1882.* 


Heidelburg  towns/tip. 

182.  Diamond  Slate  quarry  (Fig.  17),  leased  by  Hartley 
&  Bar  ;  opened  1854  ;  250x150  ;  two  large  beds,  one  24  and 
and  the  other  30  feet  thick,  separated  by  5  feet  of  small 
beds  ;  on  top  of  the  24-foot  bed  a  few  quartz  veins  /  a  few 
also  in  the  slates  above  it ;  beds  rise  slightly  E.  along  the 
strike.  At  500'  N.  of  the  main  quarry  is  an  old  abandoned 
quarry  ;  dip  45°,  S.  10°  E..  and  nothing  to  be  seen.t 

*  There  are  very  few  exposures  in  the  township  at  which  the  dip  can  be 
obtained.  On  the  small  creek  that  empties  into  Jordan  creek  in  the  south- 
west part  of  the  township,  there  are  two  dips  to  be  had  just  east  of  the  school 
house,  the  slate  dips  10°  to  the  south  and  a  quarter  of  a  mile  above  the 
mouth  of  the  creek  the  slates  are  flat,  with  a  few  small  rolls  in  them  for  half 
a  mile  on  each  side. 

f  At  S.  end  of  Germanville  slates  dip  55°  S.  On  Jordan  creek  1  in.  E. 
Pleasant  Corner,  a  sharply  folded  anticlinical  shows  dipping  60°  to  the 
south.  On  the  south  side  dip  50°  S.  ;  north  side  70°  S.  This  shows  a  tight 
compression  and  overthrow.  Half  a  mile  south  slates  dip  50°  south.  1| 
miles  up  a  small  creek  that  runs  into  the  Jordan  at  this  point,  there  is  an 
abandoned  slate  quarry  with  nothing  to  be  seen.  \\  m.  E.  of  Pleasant  Cor- 
ner slates  dip  30°  S.  20°  E. 


NO.  III.       HOOFING   SLATE   BKLT.  609 

South  Whitehall  township. 

183.  An  abandoned  slate  quarry  on  the  Huckleberrv  ridge 
synclinal  %  m.  S.  of  Guthsville,  200x100,  full  of  water; 
slates  vertical  ;  cleavage  45°  S.  ;  slates  all  thin  bedded.* 

Lynn  township. 

192.  Laurel  Hill  Slate  Co.'s  quarry,  1m.  IS.  E.  of  Lynn- 
port  ;  75x50x60  ;  dip  vertical  ;  cleavage  steep  toS.  40°  E.  ; 
beds  worked  are  26',  10',  8',  6'  and  2'  in  length  along  the 
cleavage 

193.  Lynnport  Slate  quarry,  at  Lynnport,  north  of  the 
railroad,  150x100x60  feet.* 

194.  Two  abandoned  quarries  at  Slateville  ;  the  one  beside 
the  road  shows  the  northern  half  of  the  anticlinal  axis, 
with  one  bed  4  feet  thick  ;  the  other  quarry  shows  the  slate 
dipping  about  45°  S.,  with  one  bed  4  feet  thick. 

195.  Star  Slate  quarry  (Fig.  18),  George  W.  Griesheimer 
ct  Bro.,   at  New  Slateville,  one  mile  northwest  of  Stein- 
ville  ;  started  about  1868  ;  worked  by  the  present  owners 
silica  1876 ;  make  about  7500  squares  a  year.     The  cross 
section  Fig.  18  shows  one  large  bed  30  feet  thick.- 

Quarries  in  Berks  county. 
Albany  townshiy. 

195.  Centennial  quarry,  1£  m.  W.  of  Steinsville,  Faust, 
Heinly  &  Bros.,  150x50x80;  80°,  N.  20°  E.  The  section 

*Low  Hill  township  has  no  quarries.  At  its  X.  E.  corner  slates  dip  15°, 
S.  60°  W.  ;  i  in.  further  down  a  small  run  the  dip  is  45°  N.  with  cleavage 
45°  S.  curled.  Just  below  Low  Hill  on  the  Jordan  slates  dip  30°  S.,  cleav- 
age curly.  A  few  hundred  yards  further  down  the  dip  is  30°  S.  1|  m.  down 
the  creek  slates  dip  50°,  N.  10°  W.,  dark  blue,  thin  bedded,  with  no  regular 
cleavage.  \  mile  further  down  the  dip  is  50°,  S.  20°  E.,  slates  massive,  cleav- 
age irregular.  In  the  road  across  the  Weidasville  bend  in  the  creek  the 
ground  is  covered  with  pieces  of  quartz.  1|  miles  down  the  creek  from 
Weidasville  the  slates  are  flat.  Half  a  mile  S.  of  Low  Hollow  P.  O.  slates  dip 
50°,  S.  10°  W.  ;  cleavage  parallel  to  dip.  At  the  northwest  corner  of  the  town- 
ship slates  dip  80°  S.  One  mile  N.  E.  of  Lyons  Valley  P.  O,  slates  are  flat. 
One  mile  S  of  Claussville  slates  are  flat ;  and  on  the  creek  in  the  southwest 
corner  of  the  township  veins  of  quartz  show  in  the  slate. 

*1|  m.  E.  of  Lynnport  slates  dip  55°  S. 


610  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 


M.ffA     tu&eAter  {flak 

Phyllo^ptu.  typn..     A  grap.clite  .gured  by  H.II,  Pa. 


NO.  III.      ROOFING   SLATE   BELT.  611 

cut  shows  the  quarry  and  a  small  opening  made  on   the 
large  bed  to  the  south. 

196.  An  abandoned  quarry,  east  of  the  Centennial,  nearly 
on  the  county  line;  bed  20  feet  thick,  dipping  70°  N.. 
cleavage  vertical. 

Weisenburg  town.sliip. 

199.  Old  quarry,  east  of  Siepstown,  near  the  township 
line ;  dip  70°,  S.  20°  E  ;  cleavage  20°,  S.  20°  E.,  tolerably 
perfect ;  slates  look  like  good  roofing  slates.* 

Albany  township. 

S05.  John  GiW  s  flagstone  quarry  is  two  miles  from 
Kempdon  station.  The  sandstone  dips  65°  south.  The 
strike  of  the  rocks  would  carry  it  directly  into  the  point  of 
the  mountain.  The  sandstone  conies  out  of  the  quarry 
with  rough  faces,  but  after  being  dressed  it  looks  good. 
Just  north  of  the  quarry  slates  dip  35°  south. f 

*One  mile  south  of  this  slates  dip  10°  N. ;  and  |  m.  further  south,  in  upper 
Macungie  township,  slates  dip 20°  to  the  south.  H  miles  N.  of  Seiberlings. 
ville  an  outcrop  of  red  slate  shows  in  the  road,  but  it  is  not  roofing  slate- 
One  mile  north  of  Seiberlingsville,  along  the  curve  of  the  hill,  there  is  an 
outcrop  of  thin  bedded  grey  sandstone ;  also  some  light  green  slate.  This 
outcrop  shows  for  about  a  mile. 

f  At  Trexler's  station  the  slates  dip  20°,  S.  20°  W.  |  a  mile  west  they  dip  45° 
to  the  south.  Just  east  of  the  Mountain  Post  Office  the  dip  is  64O,  s.  10°  E. 
|  a  mile  west  of  the  Post  Office  it  is  80°,  S.  20°  E.  1*  miles  west  of  the  Post 
Office  the  dip  is  63°,  S.  10°  E.  Going  on  west  into  the  cove  at  Digby  Miller's 
the  dip  is  80°,  S.  10°  W.  At  S.  Knesler's  it  is  52°,  S.  10°  E.  At  William  Bo- 
lick's  it  is  90°,  S.  10  E.,  and,  also,  near  the  same  place  it  is  75°,  S.  10°  E.  At 
John  Berg's  it  is  90°.  At  this  place  there  are  thin  bedded  dark  gray  slates, 
with  inter-bedded  sandstones.  The  sandstone  is  fine  grained  and  in  thin 
layers.  The  outcrop  shows  500  feet  of  slates  and  sandstones.  At  the  new 
Bethel  church  the  slates  are  vertical.  Just  north  of  the  church  they  dip  45° 
to  the  south; 

One  mile  east  of  J.  Gilt's  quarry  there  is  red  slate  with  dip  of  20°,  S.  10° 
E.  The  slate  has  patches  of  green  in  it.  On  the  road  just  below  the  grist 
mill  slates  and  inter-bedded  sandstones  dip  45°,  S.  20°  W.  200  yards  south 
red  slates  show  40  feet  thick  ;  dip  about  60°,  S.  Opposite  the  school  house, 
light  greenish  sandstone  makes  the  high  ridge  to  the  east  called  Round  Top. 
1000  feet  further  down  red  slate  shows.  J  m.  south  of  the  grist  mill  thin 
bedded  olive  slates  dip  80°  N.  A  shaft  on  Stone  run  1|  miles  above  its 
mouth  was  sunk  on  red  slate,  20  feet  deep  ;  red  slate  20  feet  thick,  some  ol 
it  has  spots  of  green  in  it ;  also,  some  green  slate  ;  no  roofing  slates ;  cleav- 
age not  good,  i  m  N.  of  this,  a  gray  sandstone  dips  90°,  S.  10°  W.  5  m.  N.  of 


612  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 


JfiMl. 


Orthis  (Platystrophia)  biforata,  Var.  dentata.  Orthis  dicho 

///  /      3«.  ! 


g;>5-t»^v.i 

Orthis  (PlatystropMa)  biforata,  Var.  acutilirata.    (Del 

So    /":m»*~~Sl,    XTW^  St.         Orthis  jamesl,  Hit. If*  A,*     ,Ui 

JSNf  U 


LV.l 


Orthi3  clytie,  Hall,  14th  Annual 


Orthii  (Platyitrophia)  biforata.     ( Terebra  Orthis  orthambonltes, 

II.  » 


cerata'  H»»-  13">  *•  I860,  p.  12,  ; 


00  \ 


Orthis  emacerata.  v  ar.  multisecta, 


OrthU  occidentals,  Hall.  Pal.  N.  Y.  Vol.  1,  1841 
fill 


Orthis  Insculpta,  Hall,  Pal.  N.  Y.  Vol.  1, 1847. 

frl 


MfVMf 


Orthis  retro  sa  f     Salter,  (ieol.  Survey  of 


NO.  III.      ROOFING   SLATE   BELT.  613 

Wessnersville  slates  dip  45°,  S.  10°  W.  Half  a  mile  south  of  Wessnersville 
red  slates  dip  90°  S.  2  m.  S.  E.  of  Wessnersville  olive  slates  dip  50°,  S.  30° 
E.  1  m.  W.  of  last  is  a  red  slate  outcrop. 

Greenwich  township  has  no  quarries.  On  the  railroad  \  m  W.  of  town- 
ship line,  slates  dip  58°,  S.  20°  E.  Opposite  Lenhartsville,  slates  and  thin 
bedded  sandstone  dip  55°,  S.  20°  E.  At  the  road  crossing  red  slates  show. 
On  the  small  creek  2  in.  N.  E.  of  Lenhartsville  red  slates  dip  55°  S.  1|  m. 
E.  of  Smithsville,  a  fifty  foot  outcrop  of  red  slate  in  the  road.  |  m.  N.  of 
Smithsville  red  slates  crop  out.  2  m.  W.  of  Smithsville,  15  feet  of  red  slate 
dip  55°,  S.  20°  E.  At  Klinesville,  red  slate  outcrop.  The  hill  1  m.  S.  of 
Klinesville  is  made  of  fine  grained,  thin-bedded  sandstone.  On  the  south 
side  of  the  hill  red  slates  show  in  layers  as  far  as  the  school  house  and  along 
the  road  to  the  east  for  a  mile  and  a  half,  i  m.  S.  of  Smithsville  slates  dip 
200,  S.  400  W. 

Half  a  mile  further  there  is  an  outerop  of  massive  flaggy  sandstones. 

There  aie  two  small  outcrops  of  limestone  in  the  township  ;  the  northern 
is  on  S.  D.  Kohler's  farm  ;  length  of  outcrop  unknown  owing  to  loose  slate 
covering  it.  Just  north  of  this  outcrop  the  slates  dip  35°,  S.  2QO  E. 

The  other  limestone  outcrop  is  half  a  mile  south  of  W.  Heffner's  grist 
mill ;  dip  10°  N. ;  limestone  blue  and  thin  bedded. 

Maxatawny' 'township  has  no  quarries.  1|  m.  N.  of  Kutztown  the  slates  are 
flat :  also  \  a  mile  north  of  this,  on  top  of  the  hill  above  the  j  unction  of  the 
slate  and  limestone,  the  slates  lie  flat,  but  at  the  lower  side  of  the  same  cut 
dip  45°  west 

Richmond  township  has  no  quarries.  E.  of  Virginsville  one  mile,  lime- 
stone outcrops  ;  the  most  northern  dips  30°  N.  A  quarter  of  a  mile  south 
(with  slate  showing  between)  the  limestone  lies  flat  with  rolls  in  it.  Half  a 
mile  south  of  this,  with  slate  between,  the  limestone  dips  30°  north  ;  it  is 
dark  blue,  thin  bedded,  and  shows  100  to  200  feet,  and  has  the  appearance  of 
the  Trenton.  Along  the  small  creek  half  a  mile  east  of  this  there  is  no  lime- 
stone to  be  seen  ;  therefore  the  outcrop  is  probably  that  of  a  sharp  anticlinal. 

Two  and  one-half  miles  E.  of  Virginsville  thin  bedded  sandstone  dip  30°  S. 
£  m.  E.  of  Merkel's  saw  mill  slates  dip  90°  W. ;  also  some  fine  grained  sand- 
stone. Just  below  Merkel's  saw  mill  slates  dip  35°,  S.  30  E.  On  the  hill 
north  of  Moselem  furnace  slates  dip  15°,  S.  60°  W.  £  m.  S.  of  Moselem 
furnace  slates  dip  20°  north.  1  m.  W.  of  the  furnace  the  dip  is  flat. 

Windsor  township  has  no  quarries.  At  school  house  No.  4  slates  dip  90°, 
S.  30°  E.  with  some  slaty  sandstone.  300'  S.  red  slate  shows  for  half  a  mile 
east  |  m.  S.  of  St.  Paul's  church  red  slates  show  for  GOO  feet  acrossthe  out- 
crop; no  dip  visible;  £  m.  E.  the  same  dip  S.  60°,  S.  30°  E.  1^  m.  E.  of 
Hamburg  slates  dip  50°  south.  1  m.  E.  at  the  old  railroad  grading  alter- 
nate beds  of  slate  and  sandstone  dip  52°  S.  20°  E.  At  the  east  end  of  Ham- 
burg sandstone  outcrops  in  the  road.  1  m.  N.  of  Hamburg  alternate  beds 
of  slate  and  sandstone  dip  75°,  S.  10°  E.  waving.  £  m.  below  the  lock- 
house  sandstone  dips  10°  E.  (massive  sandstone  of  IV).  500'  further  up 
the  river  dark  gray  slates  dip  50°,  S.  20°  E.  200  feet  shows  underneath  gray 
slate,  slaty  sandstone  and  thick  bedded  sandstones. — 1  m.  E.  of  Hamburg 
slates  dip  60°  S.  |  m.  further  east  fine  grained  olive  sandstone,  15  feet  thick, 
thin  bedded,  dips  80°,  S.  10°  E.  South  of  the  run  red  slate,  30  to  50 feet,  dip 
50°,  S.  10°  E.  1  m.  N.  of  Windsor  Castle  slates  dip  60°  south.  ^  m.  N.  of 
Windsor  Castle  slates  dip  35°  south.  1|  m.  E.  of  Windsor  Castle  slates  dip 
60°  south. 


614  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA 


MMl. 


LV/. 


Crthia  oinnata,  HaM.  Pal.  N.  Y.  Vol.  1,  1847,  Ifud.  lit 

un 

*r*fe 


rieurotomona  '.Scalituf)  tropldophora,  "get. 

Pholidop.   Cincinnati 


Orthodesma  parallelum.  ( Orikmota  parallel*. 
OrthodeBma  corvatum,  H    &  W  1'al.  Ohio,  ,|tg «»^^^^^^^I4 

"'!'       *fP^ 

m 


Orthoceras  capitollnum.  S»fford      Geol.  Tenn.  1869 


Sal-ford. 

Orthoceras  dnseri, 


Gfol.Tenn.rU 


NO.   III.       ROOFING   SLATE   BELT.  615 

Perry  township. 

244-  A  flagstone  quarry,  at  the  northeast  corner  of  the 
township,  worked  by  Jacob  Derby.  The  stones  make  good 
flagging,  and  are  taken  out  generally  2' X  3' X  3"  in  size.  Some 
are  10  feet  long.  They  are  dark  gray  and  come  out  regu- 
larly. The  sandstones  roll  to  the  north  and  south  and  dip 
to  the  northeast.* 

850.  W.  Collier's  flagstone  quarry,  f  m.  N.  E.  of  Shoe- 
makersville,  is  150  feet  long.  10  feet  of  flagstone  exposed 
has  from  5  to  10  feec  of  broken  slate  on  top.  Stones,  from 
2'  to  4'x5'  to  8',  show  dark  gray  generally,  2  inches  thick, 
with  smooth  faces.  The  joints  are  not  regular,  making  a 
loss  of  about  one-third  in  squaring  them  up.  Half  a  mile 
southeast  of  this  quarry  the  slates  dip  80°  south. 

£51.  A  small  flagstone  quarry,  two  miles  east  of  Shoe- 
makersville,  20x30x10  feet.  The  stones  on  the  pile  are 
6x6x3  feet;  quarry  full  of  water.  One  mile  south  the 
slates  dip  50°,  S.  10°  W.f 

*  Half  a  mile  west  slates  dip  50°  south.  500  feet  south  limestone  outcrops ; 
30  ieet;  shows  west  for  three  miles.  Just  west  of  the  Zion  church  it  is  flat 
with  rolls  in  it  {  m.  N.  of  the  church  slates  dip  50°  south.  1000  feet  south 
of  the  limestone  red  slate  outcrops.  One  mile  south  of  the  above  limestone 
outcrop  is  another  about  parallel  to  it.  On  Peter  Folk's  farm  the  limestone 
dips  under  the  slate  at  an  angle  of  20°  to  the  south.  At  the  corner  of  the 
roads  the  slate  dips  18°,  S.  70°  west.  1  mile  further  west  the  limestone  dips 
32U  south  ;  light  blue  and  broken.  lj  in.  further  west  the  limestone  dips 
20°,  S.  20°  E.  Is  light  blue  with  some  siaty  limestone  on  top.  Limestone 
shows  again  at  the  creek  above  the  grist  mill. 

t  At  the  north  end  of  Mohrsville  the  slates  are  flat  1|  m.  N  of  Shoe- 
makersville  on  the  canal  slates  dip  45°,  S.  30°  W.  200  feet  further  north, 
dip  90°,  N.  30  E. ;  probably  an  anticlinal  brings  up  the  limestone  further 
east.  1  m.  further  up  the  canal  slates  dip  60°  S.,  30°  W. 

In  Ontelaunee  township,  1  m.  N.  of  Evansville,  limestone  outcrops  show 
100  feet  wide.  1J  m.  E.  of  Leesport  slates  dip  55",  S.  20°  K.  1  m.  N.  of 
Leesport,  slates  and  some  slaty  sandstone  dip  40°,  S.  20°  E.  The  Crane 
Iron  Co.Js  ore  bank,  2|  m.  N.  E.  of  Leesport  consists  of  two  open  cuts  now- 
full  of  water.  At  one  place  could  get  a  slate  dip  of  45°  south.  The  surface 
is  covered  with  loose  slate,  and  pieces  of  slate  coated  with  hematite.  From 
the  looks  of  the  dump  I  should  say  that  the  mine  had  a  great  deal  of  slate 
in  it. 


616  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 


JotiH Aeaweejk 

Copied cund reduced,  to /*jroin,jiyivreA 


NO.  III.      FOSSILS.  617 


CHAPTER  L. 
The  Fossils  of  No.  III. 

The  Utica  Slate  (Ilia)  formation  is  very  fossiliferous 
in  Newfoundland,  Labrador,  the  island  of  Anticosti,  Can- 
ada (as  far  west  as  Lake  Huron,  where  it  thins  out),  Ver- 
mont, New  York,  New  Jersey  and  middle  Pennsylvania, 
its  characteristic  fossil  everywhere  being  a  beautiful  little 
qnaker-like  trilobitethe  Triarthrus  (three  jointed)  becMi  of 
Green*.  On  the  Ohio  river  this  fossil  is  abundant,  asso- 
ciated with  Leptobolus  lepis  and  other  Utica  forms,  not  in 
black  slate  but  in  blue  lime  shales  and  marls,  which  are 
beds  of  passage  from  the  Trenton  limestone  beds  up  into 
the  Hudson  River  slates,  as  in  Lebanon  and  Cumberland 
counties  Pennsylvania ;  and  also  in  the  Western  States. 
None  of  its  characteristic  fossils  are  found  in  the  Galena 
limestone,  and  none  of  the  characteristic  Galena  forms  nre 
found  in  the  Utica.  f 

In  Centre  county,  Professor  Evving  cites  Matternville  as 
a  good  locality  for  seeing  the  sandy  slates  at  the  base  of 
the  Hudson  River  formation  graduating  downward  into 
the  Trenton  through  a  series  of  limy  layers  which  carry 
"fossils  common  to  the  Trenton  and  Utica.* 


*  Monograph  of  Trilobites,  1832.  Other  species  of  this  genus  are  T.  cana- 
densis,  Smith;  T.  glaber,  Billings;  and  T.  spinosus,  all  in  the  Utica  and 
the  last  very  abundant  in  Canada.  S.  A.  Miller,  p.  44.  The  figures  of  these 
trilobites  are  given  life-size  in  my  Dictionary  of  Fossils  in  Pa.  Report  P4, 
Vol.  3,  1890,  pp.  1208,  1209  ;  and  reduced  to  one-half  linear  on  plate  38,  p.  526, 
and  plate  43,  p.  536,  above. 

fS.  A.  Miller,  p.  44. 

JThe  whole  of  No.  Ill,  Utica  and  Hudson  River  combined  seems  to  be 
only  800  feet  thick.  At  Egg  Hill  in  Penn's  valley,  and  Spring  Mills,  tran- 
sition (Utica)  shaly  limestones  holding  Trenton  fossils  are  well  seen.  Me- 
tween  Jacksonville  and  Howard  near  the  base  of  Bald  Eagle  mountain  a 
tough  black  lime  shale  crops  out  (overturned  to  60°)  ;  and  near  Hoy's  house, 
at  the  base  of  the  mountain  (that  is,  high  in  III)  fossils  are  seen  like  those 
at  Egg  Hill. 


618  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 


,a&ffiafy6t  1/orJr  county 


NO.  III.      FOSSILS.  619 

Prof.  Ewing  makes  no  attempt  to  separate  the  Utica  from 
the  Hudson  River,  but  names  the  following  list  of  fossils  of 
No.  Ill  as  a  whole  as  being  in  his  collection  : 

Stems  of  Glyptocrinus  decadactylus  ;  Orthis  lestudin- 

aria;  a  cast  of  OrtTiis  subquadrata(\) ;  OrlJiis /  Stro- 

phomena  alternata ;  Leptcena  sericea ;  BelleropJiou  bilo- 
batus  ;  Murcltisoniagracilis  ;  Modiolopsis  modiomorpha  ; 

Modiolopsis  curta  ;  Ambonychiaradiata;  OrtJionota, ; 

Trinucleus  concentricus  ;  Callimene  ( Triarthrus)  becJcii ; 
Callimene ;  Orthoceras .* 

The  Utica  fossils  catalogued  in  C.  Hall's  special  collec- 
tion for  the  Survey  (O3,  p.  190  to  192)  consist  of  44  indi- 
viduals of  Triarthrus  (Calymene)  beck  ft,  got  by  him  at 
Bellefonte,  with  crinoid  stems,  fragmental  and  poor  ;  also 
47  hand  specimens  collected  by  W.  A.  Fellows,  along  the 
Bellefonte  outcrop,  some  of  them  slabs  showing  on  their 
surfaces  numerous  fragments  of  that  trilobite,  mostly  heads, 
comparatively  few  bodies,  and  these  nearly  all  more  or  less 
crushed  or  distorted  ;  tail  pieces  comparatively  rare.  Also 
85  other  specimens  of  the  same  trilobite. 

These  suffice  to  show  the  vast  abundance  of  this  charac- 
teristic trilobite  life  in  that  .part  of  the  Utica  sea  which 
covered  middle  Pennsylvania.  No  doubt  any  collector 
could  fill  his  cabinet  with^individual  specimens  at  any  place 
along  the  numerous  and  very  extensive  outcrop  lines. 

In  Bedford  county,  the  Utica  black  shales,  about  200' 
thick,  containing  a  few  compact  slate  layers  an  inch  or  so 
thick,  show  a  few  graptolites.  They  pass  gradually  up- 
ward into  brown  shales,  and  then  into  non- fossil  if erous 
yellow  shales  which  make  up  the  mass  of  the  Hudson  River 
formation,  some  thin  sandstones  being  seen  near  the  top. 
The  whole  of  III  is  only  about  700'  thick,  f 


*  Report  Centre  county,  T4,  1884,  page  427.  He  adds  that  most  of  these 
forms  are  found  also  in  the  Trenton  limestones.  So  far  as  the  fossils  can 
guide  us  in  the  identification  of  strata  at  a  distance  it  would  seem  as  if  in 
middle  Pennsylvania  only  the  lower  half  of  No.  Ill  was  deposited,  the 
upper  or  roofing  slate  division  being  wanting.  Yet  the  distance  between 
Allentown  and  Bellefonte  is  only  about  150  miles. 

t  Stevenson,  T2,  1882,  page  93. 


620  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 


Clisiophyllum  oneidense.     (Billings  Canad.  . 

VIH  a-.  Cornift/reuS  7/ 


UngTila  cuneata,  Conrmd.   (He.  Tren/on  in  Pa. 


NO.  III.      FOSSILS.  621 

The  Hudson  River  formation,  Hlb,  a  marine  deposit 
from  the  Gulf  of  St.  Lawrence  west  to  the  Red  River  of  the 
North,  and  south  to  Tennessee  and  Texas,  varies  in  thick- 
ness from  6000'  on  the  Delaware  and  2000'  in  eastern 
Canada,  to  1100'  at  Toronto,  250'  in  Missouri,  and  100'  in 
the  far  northwest. 

It  is  very  fossiliferous  around  the  Falls  of  the  Ohio,  where 
it  consists  of  800'  of  blue  lime  shales  and  limestone  layers. 
The  seas  swarmed  with  animal  life  and  seaweed,  and  many 
of  the  strata  are  composed  wholly  of  their  remains.*  Some 
fossil  forms  lived  through  the  whole  age,  and  occur  from 
bottom  to  top  : — Callimene  callicephala  /  A  saphus  gigas, 
and  megistus  ;  Bey  rich  ia  chamber  si ;  Leptcena  sericea  / 
Bellerophon  bilobalus ;  Zygospira  modesta ;  Stropho- 
mena  alternata  ;  and  Orthis  testudinaria  /  and  all  of  them 
(except  the  Beyrichid)  have  been  found  in  older  strata 
(No.  II).  L.  sericea  continued  to  live  into  a  later  age. 

Other  forms  (at  least  in  the  Cincinnati  country)  seem  to 
have  had  but  a  short  range  of  life  : — Streptorhynchus  hal- 
lianum  has  a  limited  range  in  the  lower  part  ;  Streptor- 
hynchus planoconnexum  and  sinualum  are  limited  to 
strata  below  the  middle  ;  Streptorhynchus  nutans  and  sul- 
catum  are  confined  to  the  middle  zone  of  the  upper  division  ; 
Streptorhynchus  subtentum  and  filitextum  are  confined  to 
the  upper  part.  Of  five  species  of  Lichenocrinus  three, 
crater  if  ormis,  dyer  I,  patter  soni.  are  confined  to  the  lower 
half  ;  two,  tuberculatus,  affinis,  to  the  upper  part.  Of 
species  of  the  trilobite  Acidaspis  one,  crossota,  occurs 
below  ;  two.  anchoralis,  Cincinnati  ens  is,  in  the  middle  ; 
one,  coralli,  above. — RhynclioneUa  capax  and  dentata, 
Streptelasma  corniculum,  Favistella  stellata,  Tetradium 
fibratum,  Cypricardites,  &c.,  are  confined  to  the  upper 

*S.  A.  Miller's  N.  A.  G.  and  P.  Cincin.  1889,  p.  46.  He  describes  the  out- 
crop from  Cincinnati  west,  50  miles,  to  Osgood  in  Indiana,  N.  to  Dayton, 
and  X.  E.  to  Xenia.  The  hills  at  Cincinnati  expose  the  lower  half  (400'). 
In  Kentucky  it  makes  a  circular  clay  crop  around  the  Bluegrass  country. 
It  is  rare  to  find  a  layer  of  solid  limestone  (in  the  50'  of  clay)  more  than 
one  foot  thick.  The  stone  is  a  mass  of  more  or  less  ground  up  shells,  corals 
and  crinoids. 


GEOLOGICAL   SURVEY    OF   PENNSYLVANIA. 


NO.   III.       FOSSILS.  623 

part. — Grinoids  as  a  rule  have  a  limited  vertical  range,  each 
species  holding  by  its  own  separate  horizon. 

Characteristic  and  widely  distributed  species  of  No.  Illb 
are  :  Aulopora  arachnoidea,  St^matopora  inflata,  Ortliis 
occidentalis,  Or  this  subquadrata,0rtkisretrorsa,  Pterinea 
demissa,  Pterinea  insueta,  Cyclonema  bilix,  and  Glyplo- 
crinus  decadactylus .* 

At  Henrietta  station,  in  Blair  county,  Mr.  R.  E.  Sanders 
in  1875  obtained  from  the  Hudson  River  slates  ten  speci- 
mens of  brachiopods  of  undetermined  species.  (O3,  p, 
191.) 

From  the  same  slates,  1£  miles  S.  \V.  of  the  Henrietta 
mine,  he  got  Glyptocrinus  decadactylus,  and  other  crinoid 
stem  impressions.  (O3,  p.  191.) 

From  the  same  slates  in  Leathercracker  cove,  besides  the 
crinoids,  he  collected  ScJiirod.us  cequalis ;  Triari/trus 
(Calymene)  beckii ,  a  head  of  Dalmanites  limulurus  fairly 
well  preserved  :  GraptolilTius  mucronatas  (?) ;  and  poor, 
faint,  indistinct  impressions  of  other  graptolites.  (O3,  p. 
192.) 

A  collector  of  Hudson  River  fossils  in  Middle^Pennsyl- 
vania  must  devote  a  long  time  and  close  attention  to  the 
business,  and  if  successful,  will  find  most  of  his  specimens 
injured  and  distorted  by  the  excessive  pressure  and  shear- 
ing movement  of  bed  upon  bed  which  took  place  when  the 
anticlinal  and  synclinal  waves  were  produced 

Peach  Bottom  roofing  slate  fossil  seaweeds  are  figured 
on  plates  LXX,  LXXI,  on  pages  616,  618,  above,  for  com- 
parison with  the  seaweeds  figured  on  plate  XXVI,  page 
502,  and  on  plate  CXI,  page  — ,  Chapter  LIII  on  the  fos- 
sils of  Oneida  and  Medina,  No.  IV :  and  to  illustrate  what 
is  said  on  page  183,  above. 

*S.  A.  Miller's  N.  A.  S.  and  P.,  p.  47. — See  also  a  lull  synopsis  anil  discus- 
sion of  the  relationship  of  the  Cincinnati  rocks  to  No.  Ill  and  No.  II  in  the 
east,  in  Jos.  F.  James'  paper  "On  the  age  of  the  Point  Pleasant,  Ohio,  beds," 
in  Journ.  Cincin.  Soc.  Nat.  Hist,  July,  1891 ;  in  which  the  conclusion  is 
arrived  at  that  no  beds  as  low  as  Trenton  appear  on  the  Ohio  river  within 
the  limits  of  the  State  of  Ohio. 


624  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 


I 

it  i 


NO.  IV.      ONEIDA    AND   MEDINA.  625 


CHAPTER  LI. 
Formation  No.  1 V.     Oneida  and  Medina. 

Middle  Pennsylvania  west  of  the  Susquehanna  river  is  a 
labyrinth  of  parallel  mountains,  with  straight  sloping  sides 
and  sharp  horizontal  crests,  none  of  them  elevated  more 
than  a  thousand  feet  above  the  valleys  which  they  include. 
These  mountains  interlock  in  zigzags,  sending  out  spurs 
and  knobs  into  the  large  valleys,  and  enclosing  longer  or 
shorter  narrow  parallel  coves.  (See  pi.  73,  74,  &c.) 

With  three  exceptions,  to  be  noted  directly,  all  these 
mountains  are  composed  of  Formation  No.  IV,  subdivided 
into  three  sets  of  sandstone  and  sandy  shale  beds;  the 
lowest  one  (IV a)  known  as  the  Oneida  conglomerate;  the 
middle  set  (IV  b)  known  as  the  Medina  red  sandstone; 
and  the  upper  (IV  c)  as  the  Medina  white  sandstone. 

The  Oneida  conglomerate  (IV  a)  was  so  named  by  the 
geologists  of  New  York  because  of  its  coarseness,  being  a 
pudding  stone  or  pebble  rock  ;  but  in  middle  Pennsylvania 
its  beds  are  mostly  a  gray  sandstone  interleaved  with  a  few 
beds  of  conglomerate.  Professor  Rogers  therefore  called 
it  the  Levant  gray  sandstone,  because  the  aspest  of  the  rock 
is  that  of  ordinary  sandstone.  The  Medina  or  Levant  red 
sandstone  (IV  b}  contains  so  many  interstratified  softer 
shaly  beds,  and  is  so  charged  with  iron,  turning  red  when 
exposed  to  the  air,  that  it  makes  a.  visible  division  between 
the  lower  and  upper  parts  of  the  whole  formation.  The 
uppermost  subdivision,  the  Medina  or  Levant  white  sand- 
stone (IV  c]  is  not  only  characterized  by  its  purer  color,  or 
rather  absence  of  all  color,  but  by  its  greater  massiveness, 
so  that  it  constitutes  the  real  backbone  of  the  mountains, 
cropping  out  along  their  crests. 

Formation  IV  has  been  a  boon  to  Appalachian  geolo- 
gists. It  gave  them  at  the  very  outset,  fifty  years  ago,  a  key 
40 


GEOLOGICAL    SUEVEY    OF   PENNSYLVANIA. 


BALD  EACLE  CAP  AT  BELLEFONTE 

contours  of  100 feel. 
%y  %.H Sanders. 


NO.  IV.      ONEIDA   AND   MEDINA.  627 

to  the  structural  geology  of  the  whole  region  from  Tennes- 
see to  New  York.  It  marks  the  maps  of  Pennsy  vania,  Mary- 
land, Virginia  and  Tennessee  with  topographical  lines  not 
to  be  overlooked  or  misunderstood.  It  furnished  a  safe 
basis  for  that  enthusiastic  investigation  which  resulted  long 
ago  in  the  establishment  of  the  science  of  geological  topo- 
graphy or  Topographical  Geology.  By  means  of  these 
numerous  bold  mountain  outcrops  the  plication  of  the 
earth-crust  along  the  Appalachian  belt  was  at  once  com- 
prehended and  could  be  estimated  at  its  full  value  ;  could 
be  measured,  sectioned,  mapped,  and  modelled  in  solid  form  ; 
and  a  number  of  such  models  have  been  made  by  the  Penn- 
sylvania Geological  Survey.  In  the  latest  of  these  models 
the  formations  which  cover  No.  IV  have  been  lifted  off, 
and  the  great  arches  in  the  air  (long  since  destroyed  and 
carried  into  the  Atlantic)  have  been  restored  ;  so  that  the 
complicated  structure  of  the  region  is  now  as  well  known 
as  the  internal  anatomy  of  the  human  body.  And  this  is 
due,  chiefly,  to  the  great  thickness  of  Formation  No.  IV, 
and  to  the  extensive  outspread  of  its  sandy  sediments  over 
the  bed  of  the  Appalachian  sea. 

For  a  description  of  this  model,  and  two  photographs  of 
its  surface,  see  the  close  of  Chapter  LIT. 

I  will  first  consider  the  thickness  of  the  formation  ;  sec- 
ondly the  variations  which  obtain  in  its  internal  constitu- 
tion in  different  parts  of  its  outspread ;  and,  thirdly,  the 
effect  which  these  variations  have  had  in  producing  differ- 
ent topographical  "aspects  of  the  country,  and  the  lessons 
which  they  teach  respecting  the  formation  of  mountains 
in  other  parts  of  the  world. 

The  thickness  of  No.  IV. 

First :  As  to  the  thickness  of  the  formation  as  a  whole  ; 
and  then,  as  to  the  variation  in  thickness  of  its  subdi- 
visions. 

In  measuring  the  thickness  of  any  of  our  greater  forma- 
tions there  is  almost  always  some  uncertainty  as  to  where 
the  measurement  at  the  bottom  is  to  begin,  and  as  to  where 


628 


GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 


thro 


ug 


THE  THICKNESS   OF   NO.  VII.  629 

the  measurement  is  to  end  at  the  top  ;  for,  as  I  have  already 
sufficiently  set  forth,  there  never  has  been  stop  or  pause  in 
the  tribute  of  the  rivers  to  the  sea ;  and  there  never  has  been 
uniformity  in  the  nature  of  that  tribute ;  sand  being  de- 
posited in  one  place  at  the  same  time  that  mud  was  being 
deposited  in  another  ;  and  innumerable  alterations  of  sand 
and  mud  of  every  possible  variety  have  taken  place  through 
the  entire  process.  The  bottom  of  a  formation  in  one  place 
may  not  exactly  correspond  to  its  bottom  in  another  place  ; 
and  the  same  is  true  of  its  top.  Nature  has  never  written 
its  historical  memoir  of  geological  operations  in  distinct 
and  well-rounded  sentences;  has  never  numbered  and 
headed  its  chapters  ;  has  seldom  drawn  strong  black  lines 
between  its  paragraphs.  The  formations  grade  and  fade 
away  into  each  other ;  and  that,  both  downward  and  up- 
ward ;  and  the  geologist  who  attempts  to  measure  any  for- 
mation at  any  place  must  simply  do  his  best  to  select  some 
bottom  rock  to  begin  it  with  and  some  top  rock  to  end  it 
with.  But  in  doing  this  he  is  always  liable  to  mistake. 
He  must  make  his  selections  on  his  own  responsibility.  He 
can  never  confidently  assert  that  the  bottom  and  the  top 
of  his  formations  are  established  facts  of  science.  When 
he  multiplies  his  measurements  of  a  formation  in  various 
places  in  order  to  obtain  by  comparison  a  knowledge  of  its 
variations  in  thickness  he  subjects  himself  to  the  risk  of 
multiplying  his  errors.  Sometimes,  indeed,  a  special  bed 
at  the  bottom  or  at  the  top  of  a  formation  is  so  flagrantly 
different  in  constitution,  in  color,  or  in  its  fossil  forms, 
from  all  the  other  beds  near  it,  that  he  can  adopt  it  as  a 
key  rock  with  considerable  confidence.  But  this  is  rarely 
the  case  ;  and  even  when  such  a  key  rock  presents  itself  in 
one  part  of  his  district,  and  another  such  key  rock  almost 
or  exactly  like  it  presents  itself  in  another  part  of  his  dis- 
trict, there  is  always  a  possibility  that  the  two  are  not  con- 
tinuous ;  that  they  were  not  deposited  at  exactly  the  same 
time  throughout  the  region ;  and  that  perhaps  nature  has 
repeated  the  deposit  locally  and  subsequently. 

In  measuring  No.  IV  therefore  we  have  been  obliged  to 
assume  as  its  bottom  limit  the  first  massive  sandstone  to  be 


630  GEOLOGICAL   SURVEY    OF   PENNSYLVANIA. 


THE   THICKNESS    OF   NO.  VII.  631 

seen  lying  regularly  upon  the  upper  or  roofing  slate  division 
of  Formation  No.  Ill ;  and  we  have  been  obliged  in  like 
manner  to  assume  as  the  upper  limit  or  top  of  No.  IV,  the 
highest  massive  white  sandstone  bed  which  presents  itself 
at  any  given  locality  overlaid  by  the  softer  although  still 
sandy  reddish  shale  beds  of  No.  Y  hereafter  to  be  de- 
scribed. Very  exact  instrumental  measurements  of  No.  IV 
have  been  made  in  accordance  with  this  plan,  that  is,  be- 
tween such  assumed  bottom  and  top  limits,  in  many  parts 
of  Pennsylvania :  at  the  Delaware,  Lehigh  and  Schuylkill 
Water  Gaps  ;  at  the  Susquehanna  gap  above  Harrisburg; 
at  Logan  gap  near  Lewistown;  at  Rockhill  gap  near  Orbi- 
sonia  ;  at  the  Bald  Eagle  gaps  near  Bel lefonte  and  Tyrone 
City ;  and  at  the  gaps  near  Bedford.  But  as  these  meas- 
urements were  made  by  different  assistants  of  the  Geolog- 
ical Corps  they  can  be  compared  together  only  by  making 
allowance  for  the  inevitable  differences  of  personal  opinion 
respecting  the  best  top  and  bottom  limits  of  the  formation. 
Yet,  after  all,  these  differences  are  so  moderate  as  not  to 
vitiate  the  conclusions  drawn  from  the  comparison  ;  and  we 
have  moreover  on  record  for  comparison  the  equally  intel- 
ligent and  conscientious  measurements  of  the  assistants  of 
the  First  Geological  Survey  under  Professor  Rogers,  which 
serve  in  a  measure  to  check,  and  in  fact  help  to  verify  their 
accuracy. 

The  measurement  of  No.  IV  by  Mr.  Sanders  in  Blair 
county  sums  up  2896' ;  that  of  Mr.  Dewees  at  Logan  gap 
in  Mifflin  county,  2722' ;  that  of  Mr.  Billin  in  the  south  of 
Centre  county,  2440';  that  of  Dr.  Chance  in  Clinton  county, 
2301' ;  that  of  Professor  White  at  Spruce  Creek  tunnel  in 
Huntingdon  county,  2000' (made  uncertain  by  a  fault);  that 
of  Mr.  Ashburner  in  southern  Huntingdon  county,  1808' ; 
that  of  Professor  Stevenson,  in  Yellow  creek  gap,  Bedford 
county,  2035'  (diminishing  toward  the  Maryland  line  to  less 
than  1000');  and  in  Fulton  county  about  1600';  (according 
to  Professor  Rogers'  estimate  in  Cove  mountain  2100',  and 
in  Tussey  mountain  1650').  In  the  Lycoming  county  gaps 
Mr.  F.  Platt  estimates  it  at  1375'.  Dr.  Chance's  measure- 
ment at  the  Schuylkill  Water  Gap  was  1400' ;  at  the  Lehigh 


682  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

/LXXV// 


THE   THICKNESS   OF   NO.  VII.  633 

Water  Gap  (complicated  with  a  fault)  1125' ;  and  at  the 
Delaware  Water  Gap  1565'. 

It  will  be  seen  by  the  above  statement  that  the  greatest 
observed  thickness  of  No.  IV  is  in  the  center  of  the  State, 
and  that  it  evidently  diminishes  in  all  directions  from  that 
central  district.  When  followed  southward  through  Vir- 
ginia it  thins,  at  first  gradually,  and  then  rapidly,  to  such 
an  extent  that  the  whole  formation  appears  to  be  only  about 
40'  thick  at  its  outcrop  west  of  Knoxville,  in  Tennessee.* 
Westward,  under  western  Pennsylvania  and  Ohio,  it  has 
not  been  reached  by  the  deepest  borings  ;  but  that  it  dimin- 
ishes in  that  direction  also,  is  evident  from  the  fact  that  its 
outcrop  is  too  small  to  be  recognized  in  the  Columbus  and 
Cincinnati  region.  Under  northern  Pennsylvania  and  cen- 
tral New  York  it  is  also  completely  concealed  ;  but  it  must 
diminish  in  that  direction  also,  for  its  outcrop  along  the 
Mohawk  valley  amounts  to  only  400',  diminishing  toward 
Albany  ;  and  it  makes  no  appearance  at  all  around  the 
eastern  foot  of  the  Catskill  mountains.  This  is  a  remarka- 
ble phenomenon  not  to  be  easily  explained.  To  most  geo- 
logical minds  it  will  seem'quite  sufficient  to  say,  that  dry 
land  existed  there  while  two  or  three  thousand  feet  of  sand 
and  gravel  were  being  floated  into  a  deep  sea  in  middle 
Pennsylvania.  The  difficulty  of  this  explanation  is  in- 
creased when  one  follows  the  lofty  crest  of  the  Kittatinny 
mountain  along  the  north  line  of  Berks,  Lehigh  and  North- 
ampton counties  in  Pennsylvania,  crosses  the  Delaware  at 
the  Water  Gap  into  New  Jersey,  and  follows  the  equally 
high  crest  of  the  Schawngunk  mountain  into  New  York,  to 
see  it  suddenly  cut  off  a  few  miles  east  of  the  hotels  at  Lake 
Mahunk,  to  appear  no  more  until  the  western  border  of 
New  England  is  reached.  Now,  when  'a  mountain  ridge, 
the  bold  outcrop  of  a  great  sandstone  formation  500  miles 
long  suddenly  terminates,  not  as  an  anticlinal  nose  descend- 
ing underground,  not  as  a  cynclinal  knob  rising  into  the 
air,  but  as  if  the  end  of  a  slanting  board  had  been  sawn  off, 

*In  the  White  Oak  mountains  of  East  Tennessee,  however,  it  measures 
between  800  and  900'. 


634  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 


THE   THICKNESS   OF   NO.    VII.  635 

the  structural  geologist  cannot  do.ubt  that  the  formation 
has  been  swallowed  by  a  fault.* 

*Dr.  Mather,  Geologist  of  the  First  District  of  the  New  York  Survey,  in 
his  quarto  report  of  1843,  pages  355  to  361,  describes  this  shattered  condition 
of  the  mountain.  He  says  that  the  Indians  called  the  mountain  Swang- 
gum,  that  is  "white  rock."  The  sandstone  mass  he  called  "Schwangunk 
Grit,"  and  gives  its  thickness  as  variable  between  a  maximum  of  500  feet 
and  a  minimum  of  60,  "its  usual  thickness  being  between  60  and  150."  It 
is  traversed  by  two  systems  of  faults,  one  parallel  to  the  strike  (N.  20°,  E. ), 
and  the  other  transverse  (N.  60°  W.).  The  cross  faults  are  lew  between  the 
Delaware  river  at  Carpenter's  Point  (Port  Jervis)  and  Ellen ville  and  Wa- 
warsing  in  Ulster  county,  where  the  mountain  is  traversed  by  great  breaks 
and  faults.  "The  ridge  then  sinks  and  rapidly  disappears  beneath  the  val- 
ley, while  several  wrinkles  or  parallel  axes  of  elevation  spring  up  on  the 
east  at  the  same  height,  run  eastward  between  the  Stony  Kill,  Mule  Kill, 
Sanders'  Kill,  etc.;  sink  down  gradually  towards  the  mouths  of  these 
streams,  and  finally  disappear  below  the  valley  in  Rochester  and  Marble- 
town,  or  show  their  continuation  only  by  low  broken  ridges  of  upheaved  lime- 
stone. These  axes  of  elevation  are  terminated  apparently  on  the  south  by 
the  high  cliffs  along  the  transverse  lines  of  fault.  On  the  cast  of  these  minor 
axes  the  main  axis  of  elevation  takes  its  rise  from  High  Point,  which  is  a 
high  cliff  of  grit  rock  on  the  main  fault,  and  ranges  thence  northeastward, 
more  or  less  broken  and  dislocated  by  minor  transverse  and  oblique  faults, 
and  diminishing  in  height  until  the  Shawangunk  mountain  and  its  grits, 
which  envelope  most  of  its  higher  parts,  entirely  disappear  below  the  lime- 
stone and  quarternary  deposits  at  and  near  Rosendale.  Several  high  points 
with  mural  fronts  and  ends  are  seen  between  High  Point  and  Springtown, 
as  Sam's  Point,  Great  Mogunk,  Puntico  Point,  etc.,  all  of  which  are  caused  by 
faults  along  the  main  features  of  the  mountain.  It  has  been  mentioned  that 
the  wrinkles  or  subordinate  axes  of  elevation  seem  to  terminate  at  these 
rocky  points  on  S.  E.  side  of  the  mountain,  but  the  termination  is  only  ap- 
parent, caused  by  transverse  fractures.  The  ridges  almost  all  slope  down 
to  the  N.  and  N.  E.  from  where  the  main  fractures  cross  each  other,  and  the 
rocks  disappear  below  the  more  recent  formations,  while  their  southward 
extremities  almost  always  present  high  precipitious  and  often  vertical  cliffs.." 

Although  these  statements  of  Mather  are  not  A'ery  lucid,  they  are  substan- 
tially correct,  as  any  geologist  may  observe  who  makes  one  of  the  great  sum- 
mer hotels,  the  Mohunk  or  the  Manawaska,  his  headquarters.  Overlooking 
lakes  which  lift  on  top  of  the  mountain,  surrounded  by  vertical  cliffs  of 
sandstone  and  conglomerate,  and  dammed  by  glacial  moraines,  these  com- 
fortable and  hospitable  places  furnish  unrivaled  iacilities  for  exploring  one 
of  the  most  interesting  and  instructive  fields  of  geological  research  in  Amer- 
ica. Mather's  illustrations  of  the  Shangunk  grit  and  its  fractures  on  plates 
V,  f.  13 ;  VI,  f.  7  ;  VIII,  f.  2,  3,  4 ;  VIII,  f.  4 ;  XV,  f.  3 ;  XXVI,  f.  4,  5,  6,  7, 
and  XXXIX,  f.  1,  2,  3,  are  so  bad  as  to  serve  no  purpose  but  that  of  contrast- 
ing the  slovenly  and  absurd  drawings  of  his  day  with  the  precise  and  math- 
ematical sections  of  our  own.  Yet  even  then  the  best  geologists  like  Hall, 
Logan,  Lyell  and  Murchison  illustrated  their  lucid  English  text  with  wood 
cuts  hardly  since  surpassed  for  correctness  and  beauty. 


636  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 


LXX/X. 


AT  THE   GAP   ABOVE   HARRISBURG.  637 

At  the  Gap  above  Harrisburg. 

From  the  list  of  localities  above  mentioned  where  For- 
mation No.  IV  has  been  measured  to  obtain  its  total  thick- 
ness, one  locality  has  been  omitted  because  it  requires  a 
separate  and  special  consideration,  namely,  the  gap  of  the 
Susquehanna  above  Harrisburg.  Three  separate  measure- 
ments have  been  made  in  this  gap  by  Professor  Rogers  by 
Mr.  Sanders,  and  by  Professor  Claypole,  without,  however, 
reaching  absolutely  sure  results,  owing  to  the  overturned 
and  somewhat  crushed  condition  of  the  formation.  Every- 
where else  along  the  line  of  the  Kittatinny,  Blue  or  North 
mountain,  from  the  Delaware  to  the  Potomac,  the  beds  of 
No.  IV  slope  northward  and  westward  at  various  angles 
from  20°  up  to  80°  and  even  90°.  But  where  the  Susque- 
hanna  breaks  through,  the  earth  movement  from  the  south 
has  done  more  than  press  up  the  beds  into  vertical  attitudes  ; 
it  has  pushed  them  over  20°  beyond  the  vertical,  overturning 
them  to  a  south  dip  of  about  70°.  It  will  be  shown  in  the 
next  chapter  that  this  overturn  or  inversion  affects  not  only 
Formation  No.  IV,  but  all  the  overlying  formations  up  to 
No.  XI ;  and  that  the  squeeze  produced  by  folding  20,000' 
of  rock  into  a  sharp  synclinal  basin  has  resulted  in  a  large 
amount  of  sliding  and  slipping  of  one  group  of  beds  upon 
another,  in  the  production  of  minor  irregularities  of  dip 
and  strike,  occasional  rolls,  small  faults,  etc.,  and  perhaps 
in  the  lessening  of  their  original  thickness.  How  much 
No.  IV  has  suffered  in  this  respect  is  uncertain  ;  but  it  is 
evident  that  under  such  circumstances  the  measured  thick- 
ness of  any  formation,  whether  hard  or  soft,  cannot  be  im- 
plicitly accepted  as  the  real  or  original  thickness.  At  all 
events  it  would  be  unsafe  to  draw  the  same  conclusions 
from  measurements  made  at  such  a  place  that  we  can  safely 
draw  from  measurements  made  of  it  at  places  where  no 
such  violent  upturning  and  overturning  has  occurred. 

The  measurement  of  No.  IV  in  the  Susquehanna  gap 
sums  up  less  than  500'.  This  is  at  the  southeast  corner  of 
Perry  county  ;  but  in  the  western  and  northern  parts  of 
that  same  county  No.  IV  appears  to  be  about  2000'  thick. 


638 


GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 


AT   THE   GAP   ABOVE   HARRISBURG.  639 

Following  the  mountain  only  a  few  miles  eastward  from  the 
Snsquehanna,  to  where  the  beds  of  No.  IV  lean  in  their 
natural  attitude  (dipping  north)  the  formation  becomes  of 
its  usual  thickness  ;  and  following  the  mountain  westward 
from  the  Susquehanna  not  more  than  15  miles,  the  usual 
thickness  of  the  formation  is  again  resumed.  We  have, 
therefore,  some  right  to  ascribe  its  abnormal  thickness  at 
the  Susquehanna  to  the  overturn.  Another  explanation 
tyowever  has  been  suggested  and  will  be  described  in  the 
next  chapters,  since  it  affects  still  more  seriously  Formations 
No.  V  and  No.  VI  in  this  locality. 

The  thickness  of  Formation  No.  IV  as  a  whole  is  of 
course  the  sum  of  the  thickness  of  its  three  subdivisions, 
(lower,  middle  and  upper)  Oneida, Medina  red,  and  Medina 
white.  If  the  relative  thickness  of  these  divisions  remained 
constant,  and  if  the_hardness  and  softness  of  the  beds  of 
the  three  divisions  were  everywhere  the  same,  it  is  evident 
that  the  shape  of  a  mountain  of  No.  IV  would  be  always 
the  same.  But  the  law  of  universal  geological  irregularity 
operates  upon  all  three  subdivisions.  In  fact  each  sub- 
division of  No.  IV  has  as  much  right  to  be  considered  an 
individual  rand  distinct  formation  as  if  it  had  no  topo- 
graphical relationship  with  the  other  two ;  and  the  only 
reason  why  the  three  subdivisions  of  No.  IV  have  been 
grouped  together  into  one  formation  is  the  fact  that  the 
three  together  always  make  one  mountain ;  the  shape  of 
which,  however,  necessarily  varies  with  the  Variations  in 
solidity  and  thickness  of  the  subdivisions,  as  will  be  shown 
directly.  For  the  present  we  will  regard  simply  the  thick- 
ness of  the  subdivisions;  repeating,  however,  and  insist- 
ing still  more  earnestly  upon  it,  what  has  already  been  said 
respecting  the  indefiniteness  of  the  bottom  and  top  limits 
of  all  formations  and  groups  of  beds.  If  the  three  sub- 
divisions of  No.  IV  had  been  made  by  a  stone  cutter  out 
of  three  slabs  of  rock  placed  one  upon  another  there  would 
be  no  uncertainty  as  to  their  thickness ;  but  seeing  that 
they  are  three  artificial  groupings  of  an  immense  number 
of  sand  and  mud  deposits,  each  varying  in  its  individual 
character  and  thickness,  white  and  gray  sandstones  alter- 


640  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 


«       LXXX/ 


THE   THICKNESS   OF    NO.    IV.  641 

nating  with  gray  and  reddish  muds,  it  is  extremely  diffi- 
cult to  decide  upon  any  fixed  planes  of  division  between 
them.  All  that  we  can  do  is  to  group  the  lower  gray  sands 
togther  as  the  Oneida,  the  upper  white  sands  together  as 
Medina  white,  and  call  the  softer  and  more  or  less  reddish 
beds  between  them  as  the  middle  division,  or  Medina  red; 
and  arrange  their  thicknesses  at  the  various  places  where 
they  have  been  measured  in  a  table  like  the  following : 

At  the  Delaware  Water  Gap.     H.  M.  Chance  /* 

Medina  upper  sandstone, 200' 

"       upper  shales,  etc., 530,    . 

"       white  conglomerate, 200' 

"       lower  shales,  etc., 110' 

Oneida  gray  sandstone, 75'    "j     roe» 

"       lower  shales,  etc., 240'    ^ 

"       white  conglomerate, 210'    J   1565' 

At  the  Lehigh  Water  Gap.     H.  M.  Chance  :f 

Medina  upper  sandstone, 85'  \ 

"      upper  shale, 180'  I 

"       gray  sandstone, 70'  f 

"      lower  shale, 330'  J 

Oneida  cong.  sandstone, 290'    )     460' 

"      conglomerate, 170'    i   .„  , 

*  H.  D.  Rogers  gives  different  measurements  of  No.  IV  at  the  three  water 
gaps,  in  Geol.  of  Pa.,  1858,  Vol.  I,  p.  126  to  130. 

At  the  Delaware :  Levant  White  sandstone  (some  sparsely  pebbly  beds) 
making  a  prominent  rib  of  the  mountain,  200',  (overlying  sandstone  and 
slate  alternations,  may  be  added,  or  may  be  thrown  into  the  formation  V.) 
2.  Levant  Red,  wanting.  3.  Levant  Gray  (Oneida)  ,  upper  division  thin 
bedded,  soft  sandstones,  400' ;  lower  pebbly  member,  300'.  Total,  900',  in- 
stead of  Dr.  Chance's  1565,  the  latter  being  the  result  of  instrumental  meas- 
urements of  subdivisions. 

|H.  D.  Rogers,  at  the  Lehigh:  1.  Levant  White;  top  division,  massive 
grey  and  red  sandstone  with  shale  partings,  100' ;  shales  and  flags,  300'  ; 
sandy  shales,  30'  ;  sandstones  and  shales,  with  fucoidal  mar  kings,  50' ;  sand- 
stones and  shales,  100' ;  white  and  gray  pebble  rock,  80' ;  concealed  (sand- 
stone and  shale)  beds,  200' ;  total  760'.  2.  Levant  Red,  wanting.  3.  Levant 
Gray  (Oneida)  fine  sandstone,  small  conglomerate  and  shale,  200' ;  coarse 
pebble  rock  and  sandstone,  75'  ;  fine  sandstone  and  coarse  conglomerate,  75  ; 
very  coarse  pebble  rock  at  bottom,  50' ;  total,  400'.  Total  thickness  of  IV, 
1160',  agreeing  remarkably  with  Dr.  Chance's  instrumental  measure  above, 
1125'. 

41 


642  GEOLOGICAL   SURVEY    OF   PENNSYLVANIA. 


THE   THICKNESS   OF    NO.    IV.  643 

At  the  Schuylkill  Water  Gap.     H.  M.  Chance  ;* 

Medina  upper  sandstone, 90'    "j 

"       upper  iron  shales, 480'     I 

"       white  sandstone, • 60'    j   1230/ 

"       lower  iron  shales, 600'    J 

Oneida  white  conglomerate, 200 

1430' 

At  the  Susquehanna  Gap.     H.  D.  Rogers. f 

Medina  upper, 300'  to  400'   \ 

"       lower  (red), 0'    J>  max.  470' 

Oneida, 60'  to   70'  J 


In  the  Juniata  gaps  of  Perry  county.      E.  W.  Claypole  : 

Medina  sandstone  and  shales 1500'    )    2000* 

Oneida  conglomerate  and  sandstone, 500'    > 

*  Rogers  gives  no  measurements  at  the  Schuylkill  and  Swatara  Water 
Gaps. 

The  bottom  coarse  red  pebble  rock  of  the  Oneida,  only  5'  thick,  with 
white  coarse  sandstone,  full  of  fault  slips  which  suggest  a  greater  thickness 
than  40',  is  separated  from  the  visible  upper  limit  of  No.  Ill  slate  by  a  con- 
cealed interval  of  50'  more  or  less.  Prof.  Claypole  in  his  report  on  Perry 
Co.,  F2,  1885,  p.  310,  describing  Rye  township,  makes  the  Medina  rock  rib  of 
the  mountain  to  be  only  100'  thick,  and  says  nothing  about  the  Oneida.  He 
places  500'  of  "  soft  material"  between  the  top  of  the  Medina  and  the  bot- 
tom of  the  Clinton  Iron  Sandstone  rib  which  makes  the  other  crest  of  the 
North  mountain  at  Sterrett's  gap,  the  Medina  crest  being  the  lower  of  the 
two  and  in  Cumberland  county.  In  Carroll  township,  he  says,  the  Medina 
makes  little  or  no  show,  running  along  south  of  the  county  line  on  the 
crest  (F2,  159).  The  same  in  Spring  township  (p.  333).  Tyrone  township, 
next  west,  gives  vertical  Medina  at  McClure'sgap  (p.  370).  I  have  expressed 
my  belief  and  the  reasons  on  which  it  is  based,  that  this  excessive  thinness 
of  No.  IV  and  the  total  disappearance  of  one  or  two  thousand  feet  of  over- 
lying measures  in  Perry  county,  west  (and  east)  of  the  Susquehanna  Water 
Gap,  described  by  Prof.  Claypole  in  F2,  p.  303  (see  illustration  p.  304),  and 
assumed  by  him  as  good  evidence  of  the  existence  of  a  district  of  dry  land 
in  Upper  Silurian  times  in  that  district  of  the  State,  is  rather  to  be  explained 
by  the  upturned  and  overturned  condition  of  the  south  side  of  the  Cove 
synclinal  and  Dauphin  county  coal  basin,  producing  not  only  the  oblique 
fissuring  of  the  Oneida  outcrop  in  the  Gap,  but,  as  I  believe,  great  slip-faults 
paralled  with  the  strike,  swallowing  up  and  pressing  underground  the  softer 
formations.  I  do  not  believe  that  No.  IV  was  originally  any  thinner  at  the 
Susquehanna  than  at  the  Schuylkill  or  Delaware,  or  than  it  seems  to  be  in  the 
gaps  of  the  Juniata  river,  even  in  Perry  county,  where  in  the  Tuscarora 
mountain,  etc.  Prof.  Claypole  gives  it  a  total  thickness  of  2000'  (F2, 
page  36). 


644  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 


THE   THICKNESS   OF    NO.    IV.  645 

Logan's  gap,  Mifflin  county.     C.  A.  Ashburner: 

Medina  white  sandstone, 820'  )    21(xy 

Medina  red  sandstone, 1280'  $ 

Oneida  red  conglomerate,      . 300'  )      622,     j  2722'* 

Oneida  gray  sandstone, 313'  > 

Jack's  Narrows,  Mifflin  county.     H.  D.  Rogers: 

Levant  top  red  sandstone,! 30'    )      45)),     1 

Levant  upper  white  sandstone, 420'    )  [ 

Levant  red  sandstone  and  shale, 650'     ' 


Levant  lower  white  sandstone , 250' 

Rockhill  gap,  Orbisonia,  Huntington  county.  Ashburner : 

Medina  white  sandstone, 400'  )    JOQ/W 

Medina  red  sandstone,     930'  J 

Oneida  red  conglomerate, 158'  )      ,-gg, 

Oneida  gray  sandstone, 410'  3 

Canoe  Mt.  gap,  Huntingdon  Co.     H.  D.  Rogers  : 

Levant  (upper)  Avhite  sandstone,§ 550'    "l 

Levant  (middle)  red  beds,|| 1050     i  2100' 

Levant  (lower)  gray  sandstone,  T 500'    J 

Bald  Eagle  Mt.  gaps  in  Blair  Co.     R.  H.  Sanders : 

Medina  white  sandstone  (north  crest), 1068' 

Medina  red  alternations,** 520' 

Oneida  gray  sandstone  (south  brow), 1319' 

*  Rogers  does  not  measure  the  Upper  division  of  IV  here  (Geo.  Pa.  I,  p. 
130),  but  subdivides  the  Middle  division  into  (at  top)  dark  red  flags  with 
some  red  shale  pebbles,  500'  ;  coarse  friable  red  sandstones,  iron-specked, 
100' ;  pink  sandstones  with  layers  of  quartz,  slate  and  other  older  pebbles, 
400' ;  total  1000'.  The  lowest  ( Oneida)  division,  fine  massive  gray  sandstone, 
iron-specked,  he  makes  300'.  Total  only  1300'. 

fSome  of  the  layers  are  covered  with  a  net-work  of  the  sea  weed, 
Arthrophycus  harlani. 

J  These  and  other  asigned  thicknesses  given  by  Rogers  in  his  Geo.  Pa. 
1858,  have  been  proved  incorrect  by  the  close  instrumental  field  work  of  Bil- 
lin  and  Ashburner,  Sanders  and  Chance  since  1874. 

§"  Measured  with  precision."  Ponderous,  homogeneous,  fine  grained 
white  and  gray  sandstone  beds."  Geo.  Pa.  I,  130. 

||  "  Reddish  brown,  rather  argillaceous,  with  beds  of  gray  sandstone,  all 
alternating  with  much  red  shale,"  p.  129. 

1  "  Wears  its  usual  character  of  grey-greenish  and  pinkish  hard  siliceous 
massive  sandstone  beds,  p.  127. 

**The  detailed  section  of  these  alternations  will  be  found  in  Report  T, 
on  Blair  county,  by  Franklin  Platt,  1881,  p.  17,  discussed  on  p.  47.  The  de- 
scription is  minute  and  very  interesting.  The  division  made  in  the  text  is 
liable  to  a  great  modification,  inasmuch  as  the  north  crest  of  the  Bald  Eagle 


646  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 


THE   THICKNESS   OF    NO.    IV.  647 

Bald  Eagle,  Bellefonte  gap.     H.  D.  Rogers  : 

Levant  white  sandstone, 400'  to  500' 

Levant  red  sandstone  and  shale,* about  500'    I,  1550' 

Levant  upper  green  sandstone,! 380'   >  55(), 

Levant  lower  gray  sandstone,} 170'   )• 

Bald  Eagle,  Mill  Hall  gap.     H.  M.  Chance  :§ 

Medina  upper  (north  crest), 695' 

Medina  middle  (vale), 705'     <•  2301' 

Oneida  (southern  crest), 901' 

is  really  made  by  100'  of  white  sandrocks  at  the  top  of  the  section,  sup- 
ported by  255'  of  red  sandstone  beds  parted  by  layers  of  red  slate  from  6  inches 
to  5  feet  thick.  Underneath  this  355'  the  rocks  are  concealed  for  540',  and 
the  detailed  alternations  begin  and  go  down  for  1000',  leaving  the  bottom 
division  to  be  1309'  thick.  In  fact  only  400  or  500'  of  the  upper  division  of 
1068'  answer  to  the  description  of  the  White  (upper)  Medina;  the  Red 
(middle)  Medina  is  really  500+520=1020'  thick.  All  this  is  merely  a  matter 
of  classification  and  does  not  at  all  invalidate  the  correctness  of  the  detailed 
section.  The  Medina  White  is  made  up  of  hard  white  and  greenish  gray 
flinty  sandstones,  fine  grained,  compact,  homogenous,  with  almost  none  of 
the  pebbles  which  make  it  so  coarse  a  pebble  rock  in  the  North,  Blue  or 
Kittatinny  mountain  outcrop.  Its  top  beds  are  thin,  mottled  red  and  grey, 
and  often  covered  with  sea  weed  impressions.  They  are  parted  by  or  alter- 
nate with  soft  greenish  non-fossiliferous  shales.  They  are  much  specked 
with  yellow  pits  of  decomposed  iron.  The  Medina  red  upper  member  is 
made  up  of  red  clay  flagstones,  with  (toward  the  bottom)  some  other  layers 
of  small  quartz  pebbles,  flattish  fragments  of  red  shale  occur  throughout 
the  pile  of  sandstone  beds.  Such  is  its  general  character  in  Mifflin  county. 
The  Oneida  in  Mifflin  county  has  pebbles  of  quartz  and  slate  and  sandstone 
apparently  derived  from  some  antient  land  or  coast  of  No.  Ill  and  No.  I. 
But  in  Blair  county  the  Oneida  shows  obscure  vertical  plant  stems.  Steven- 
son does  not  recognize  the  Oneida  in  Bedford  county.  The  Oneida  is  char- 
acteristically speckled  and  pitted  by  the  decomposition  of  minute  granules 
of  some  iron  ore,  perhaps  pyrites.  Its  upper  subdivision  is  a  clayey  sand, 
greenish  gray,  slightly  micaceous,  ochre-pitted,  and  its  rock  beds  parted  by 
thin  fissile  yellow  shales.  The  lower  is  an  ochre-pitted  hard  gray  sand- 
stone! (T,  48. ) 

*Thin  grey  and  red  clay  sandstone  layers,  alternating  with  a  fourth  part 
red,  grey  and  greenish  shale  partings.  High  in  the  division  are  found  ver- 
tical plant  stems  like  Hall's  Scolithus  verticalis  at  Medina,  N.  Y. 

t Greenish  grey  slightly  micaceous,  specked  with  ochre,  with  thin  fissile 
greenish  slate  partings.  In  Pleasant  Gap,  Center  county,  it  is  quarried  for 
flagstones.  (T4,  428. ) 

t  Hard  gray  sandstone  without  pebbles,  but  full  of  yellow  specks. 

§  See  detailed  section  in  Report  G4  on  Clinton  county,  1880,  p.  120.  The 
subdivisions  are  empirical.  The  upper  hard,  massive,  red,  grey  and  white 
sandstones  are  not  well  exposed.  The  middle  softer  sands  and  shales  make 
the  little  trench  between  the  crests.  Then  come  hard,  massive,  white  (with 
a  few  speckled)  sandstones,  188' :  concealed,  118' ;  hard,  massive,  siliceous 
dark  grey  and  greenish  grey  speckled  beds,  155' ;  and  at  the  bottom  a  mass 
not  well  exhibited,  but  principally  hard  massive  sand  rocks,  410'. 


648  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 


THE  THICKNESS   OF    NO.    IV.  649 

Bald  Eagle  gaps  in  Lycoming  county.     F.  Platt  :* 

Medina  upper  hard  sandstone, 100'    "| 

Medina  middle  red  beds, 1200'    i>  1375' 

Oneida  hard  sandstone, 75'    j 

Wills'  Mt.  gap,  Milligan's  cove.     H.  D.  Kogers. 

Levant  white  sandstone, 400'    ] 

Levant  red  sandstone,! 800'    1  1300' 

Levant  grey  sandstone, 100'    j 

No.  IV  thins  southward  into  Virginia  and  Tennessee. 
On  the  James  river  the  whole  Medina  measures  only  300' 
and  whole  Oneida  only  90' ;  together  390'4 

Stevenson  calls  the  Medina  in  Waldron's  ridge,  Lee  Co. 
Va.,  "  evidently  more  than  300'."§ 

West  of  Knoxville,  in  Tennessee,  I  saw  it  represented  by 
only  40'  of  sandstone. 

Towards  the  west  it  entirely  disappears  from  the  Ohio 
and  Kentucky  column. 

Northward  it  thins  away  in  an  equally  remarkable  man- 
ner. At  Niagara  the  Medina  is  300'  or  400' ;  and  the  Oneida, 
in  Oneida  county,  N.  Y.,  only  100'  to  120'. 

But  going  eastward  along  its  northern  outcrop  it  increases. 
Prof.  Prosser's  general  section  of  Western  Middle  New 
York  State  gives  Red  Medina  sandstones  and  shales,  942'.  | 

*  Mr.  Platt  says  in  Report  G2,  p.  29,  that  no  exact  measurements  were  made 
for  want  of  satisfactory  exposures,  and  that  the  figures  given  above  are  only 
probable. 

t  Includes  here  a  larger  amount  of  grey  sandstone  than  on  the  Juniata. 
Rogers  says  that  in  this  main  gap  through  Wills'  mountain  into  the  cove  the 
Oueida  is  last  seen  going  south.  He  suspects  a  fault  swallowing  up  a  part 
of  the  formation,  "a  conjecture  suggested  by  the  vertical  and  shattered  con- 
dition of  the  strata  in  Buffalo  ridge  the  western  barrier  of  the  cove."  Geo. 
Pa.  1858,  p.  128. 

JJ.  L.  Campbell,  Geol.  Rich  Patch  in  "Virginias,"  Vol.  I,  No.  12,  Dec., 
1880,  illustrated  with  sections. 

§  Proceed.  Am.  Philos.  Soc.  Phila.,  Aug.,  1880. 

||  "Thickness  of  Devonian  and  Silurian  Rocks,  etc."  Amer.  Geologist, 
Oct.,  1890,  p.  205.  His  section  is  made  up  from  well-borings.  Under  his 
Medina  the  Oswego  sandstone,  210',  is  placed  in  No.  III.  In  the  Walcott  well 
on  Lake  Ontario,  red  shale  and  red  siliceous  sandstones  alternating,  meas- 
ure 690' ;  but  they  may  be  Clinton  ;  under  them  Oswego  sandstone,  210'. 
In  the  Clyde  well,  Wayne  Co.,  N.  Y.,  Medina  red  shales,  etc.,  24',  3',  915= 
942'.  At  the  bottom  of  the  Seneca  Falls  well,  Medina  red  shales  and  sand- 
stones, 150'  ;  how  much  more  unknown.  At  Rochester  Logan  made  the  Me- 
dina 600'.  Geo.  Sur.  Canada,  1863,  p.  310. 


650  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 


NO    IV.    AT   LOGAN    GAP.  651 

No.  IV at  Logan  Gap.     PL  LXXXI,  p.  64.0. 

The  best  place  perhaps  for  studying  No.  IV  is  at  the 
Gap  through  Jack's  mountain  in  Mifflin  county. 

Here  the  white  Medina  sandstone  beds  measure  820' ; 
most  of  them  consisting  of  massive  lawers  of  exceedingly 
hard  rock  varying  from  2'  to  4'  in  thickness  ;  some  of  them 
fine  grained  ;  some  of  them  slightly  argillaceous,  that  is 
the  grains  of  sand  are  imbedded  in  a  matrix  of  clay.  They 
slope  up  from  the  floor  of  the  gap  at  the  south  end  and 
make  the  upper  part  of  the  mountain  and  its  high,  bold 
rock-covered  crest,  running  eastward  toward  the  Susque- 
hanna,  and  westward  toward  the  Juniata  ;  and  it  is  the  great 
thickness  of  these  Medina  while  sand  rock  beds  that  makes 
Jack's  mountain  one  of  the  highest  in  middle  Pennsylvania. 
The  weather  acting  upon  the  slight  cement,  dissolves  it, 
and  sets  free  the  sharp  grains  of  sand,  producing  along  the 
top  of  the  mountain  collections  of  glass  sand.  Some  of 
the  more  solid  beds,  resisting  dissolution,  break  up  into 
great  blocks  which  slide  down  and  cover  the  upper  part  of 
the  northern  slope. 

The  Medina  red  middle  division  of  No.  IV  in  the  heart 
of  the  gap  is  1280'  thick.  It  consists  of  laminated  reddish 
sandstone  layers,  too  soft  and  friable  for  building  purposes, 
interstratin'ed  with  red  sandy  shales.  On  the  surface  of 
these  shales  ripple  marks  and  the  impressions  of  sun  cracks 
like  those  seen  on  a  modern  sea  shore  abound,  leading  one 
to  suspect  that  the  waters  of  that  ancient  time  were  shal- 
low, and  the  sea  bed  in  places  exposed  to  the  air  and  sun. 
But  at  the  same  time,  many  of  the  strata  are  obliquely 
cross-bedded,  as  if  deposited  in  swiftly  flowing  currents. 

Beneath  these  lie  the  Oneida  rocks,  divided  into  an  upper 
and  a  lower  group,  called  the  Oneida  red  conglomerate  and 
the  Oneida  gray  sandstone. 

The  upper  group  consists  of  massive  sandstone  strata, 
reddish  in  color,  very  coarse,  full  of  small  pebbles  which 
in  some  places  become  as  large  as  hens'  eggs  ;  the  layers 
varying  from  V  to  6'  in  thickness,  so  that  large  stones  are 
quarried  from  them  in  the  gap.  This  mass  of  pebble  rock 


652 


GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 


• 

NO.    IV.    AT   ORBISONIA.  653 

rising  at  an  angle  of  55°  to  the  brow  of  the  famous  terrace 
which  surrounds  Kishacoquillis  valley  is  310'  thick. 

The  lower  group  measures  also  310',  and  is  made  up  of 
very  hard  greenish  gray  sandstone,  the  grains  of  sand  coarse 
and  strongly  cemented  together,  mixed  with  pebbles  of 
quartz,  none  of  them  as  large  as  those  in  the  group  above. 
Some  of  the  beds  are  five  grained,  equally  hard  and  massive, 
and  contain  small  scattered  pebbles.  Some  of  the  beds 
show  a  good  deal  of  disseminated  oxide  of  iron.* 

About  25  miles  west  of  Logan  Gap  the  Juniata  breaks 
through  the  mountain  at  Jack's  Narrows. 

Here  the  Medina  white  sandstone  is  only  450'  thick,  the 
30'  of  beds  at  the  top  being  a  group  of  alternating  red,  pink 
and  gray  sandstone  layers  and  red  and  green  shales  ;  some 
of  the  sandstone  layers  being  covered  with  a  net-work  of 
sea  weed  markings  (ArtTirophycus  Jiarlani).  The  remain- 
ing 420'  consists  of  strata,  massive  and  compact,  of  white 
and  greenish  gray  sandstone,  with  scarcely  a  trace  of  any 
organic  life.  Under  these  lie  650'  of  soft  clay  sandstone 
generally  red,  and  speckled  yellow  with  iron,  current  bedded 
to  a  great  degree,  and  interstratified  with  beds  of  very  soft 
red  shale.  Under  these  lie  250'  of  greenish  white,  hard, 
sandstone,  down  to  the  bed  of  the  river  in  the  gap,  be- 
neath which  nothing  can  be  seen,  as  the  exposure  is  anti- 
clinal. 

No.  IV  at  OrUsonia.     PL  LXXXV1,  p.  650. 

At  Orbisouia,  10  miles  further  south,  Black  Log  mount- 
ain shows  No.  IY  in  Rockhill  Gap  in  its  three  divisions. 

The  Medina  white,  400'  thick,  consists  of  massive  white 
and  gray,  fine-grained,  hard  sandstone  beds  alternating  in 
the  upper  part  with  red  and  grayish  shales.  The  Medina 

*Professor  Kogers  estimated  the  middle  division  of  No.  IV  in  Logan  Gap, 
at  1000' ;  of  which  the  uppermost  500'  consists  of  dark  red  flaggy  beds  of 
mixed  sand  and  mud,  some  of  which  contains  curious  pebbles  of  red  shale 
of  unknown  origin.  Under  these  lie  100'  of  coarse  red  sandstone,  loosely 
cemented  together,  friable  under  the  weather,  some  of  them  sprinkled  with 
small  pebbles  and  showing  a  great  number  of  iron  stained  spots.  Under 
these  lie  400'  of  pale  red  sandstone  beds  containing  pebbles  of  quartz  and 
fragments  of  slate  apparently  like  No.  III.  These  1000'  of  reddish  and  more 
or  less  pebbly  soft  rocks  constitute  the  middle  division  of  No.  IV. 


654  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 


NO.  IV.    AT   SPRUCE   CREEK   GAP.  655 

red,  930',  consists  of  soft  brown  and  red  clay  sandstones 
and  shales  ;  the  sandstones  in  the  central  part  softer  and 
more  friable  and  specked  with  iron.  The  Oneida  is  divis- 
ible here  also  into  two  groups,  the  upper  (158')  consisting  of 
hard  red  and  greenish  gray,  broken  up  sandstones  with 
conglomerates  ;  the  lower  (410')  of  hard  massive  greenish 
sandstone  and  gray  conglomerate  strata. 

No.  2  Vat  Spruce  Creek  Gap. 

In  the  gap  of  the  Little  Juniata  through  Tussey  mount- 
ain 20  miles  northwest  of  Jack's  mountain  narrows,  the 
Medina  white  sandstone,  1000'  thick,  showing  few  pebbles, 
but  many  impressions  of  the  sea  weed  above  mentioned, 
descends  from  the  crest  of  the  mountain  to  the  bed  of  the 
river  southward  on  a  slope  of  20°.  Under  this  lies  700'  of 
Medina  red  sandstones  and  shales.  The  next  underlying 
200'  are  concealed  but  probably  belong  to  the  middle  divi- 
sion, making  it  900'  thick.  Under  these  concealed  rocks,  the 
Oneida  conglomerate  appears  with  its  massive  coarse  and 
pebbly  beds,  apparently  only  100'  thick ;  but  the  Spruce 
creek  tunnel  fault  at  this  place  obscures  the  section.  Frag- 
ments of  the  Medina  white,  sliding  from  the  crest  of  the 
mountain,  cover  its  southeastern  slope  and  also  the  upper 
part  of  its  northwestern  side  ;  for  the  thin  beds  broken  up  by 
the  weather  into  innumerable  flagstones  slide  upon  each  other 
down  that  slope ;  and  in  this  respect  the  surface  show  of 
Medina  formation  in  this  part  of  the  region  is  peculiar. 
The  best  place  to  see  this  operation  of  gradual  destruction 
is  in  Jack's  Narrows  before  mentioned ;  where  the  formation 
is  thrown  into  a  double  anticlinal  arch  cut  through  by  the 
river.  The  two  walls  of  the  gap  are  slopes  of  about  30°, 
entirely  covered  from  the  crest  of  the  mountain  to  the  bed 
of  the  river  with  a  smooth  and  regular  universal  stone  slide, 
composed  of  millions  of  broken  flags  slipping  over  each 
other  farther  and  farther  in  their  slow  but  never  ceasing 
descent.  The  material  thus  provided  by  nature  has  been 
thankfully  accepted  by  man  ;  and  railroad  engineers  find 
in  this  great  stone  slide  an  inexhaustible  provision  for  the 
finest  railroad  ballast  that  can  be  conceived. 


656 


GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 


LXXX/X- 


Langtudifial  Section  ofJacts  Mountain  miavmy  between  Three  Springs  and  Saltillu 
shotting  the  subsidence  at  the  Anticlinal  at  the  end  of  the  Mountajn.hyCha$.AAshbur 


r.p.n*. 


NO.    IV.    AT   TYRONE   GAP.  657 

The  ravine  which  descends  into  Spruce  creek  gap  has  been 
excavated  in  the  Medina  middle;  and  the  Juniata  river 
makes  its  very  remarkable  bend  below  the  Spruce  creek 
station  in  order  to  use  the  lower  part  of  this  ravine  for  a 
water  way.  The  long  hog-back  in  the  bend  (through  which 
the  Pennsylvania  tunnel  has  been  driven)  is  made  by  the 
Oneida  conglomerate ;  the  outcrop  of  which  slopes  up  the 
mountain  side  and  becomes  the  brow  of  the  terrace  which 
surrounds  Nittany  and  Canoe  valleys.  This  terrace  is  the 
prominent  feature  of  the  northwest  slope  of  Tussey  mount- 
ain for  many  miles  eastward. 

No.  IV  at  Tyrone  Gap. 

In  the  gap  of  the  Little  Juniata  through  Bald  Eagle 
mountain  at  Tyrone  City,  Formation  No.  IV  stands  verti- 
cal, affording  a  fine  opportunity  for  the  study  of  its  beds. 
But  all  the  beds  are  not  visible,  being  concealed  by  the  ma- 
terial which  has  slidden  from  above.  The  section  pub- 
lished in  Report  T,  page  17,  and  Report  T3,  page  144,  is  as 
follows : 

Sandstone,  white  Medina, 100  rb 

Sandstone,  red,  with  layers  of  red  slate  from  6"  to  5'  thick,  255' 

Concealed  interval, 540' 

Sandstone,  red  massive, 84' 

Sandstone,  green  slaty,     1'  8' 

Sandstone,  red,  with  a  few  layers  of  red  shale, 87' 

Slate,  green, 0'  6" 

Sandstone,  red, 10' 

Shale,  red, 5' 

Slate,  green, .   .  5' 

Sandstone,  red,     5 

Sandstone,  gray, 20' 

Shale,  red, 1' 

Sandstone,  gray, 10' 

Shale,  red, .f 0'  6" 

Sandstone,  red,     10' 

Sandstone,  grayish  red, 15 

Slate,  red, 

Slate,  green,    ...       16" 

Sandstone,  gray, 15 

Slate,  gray, 1 

Sandstone,  brown, 20 

Slate,  gray, 1 

Sandstone,  brown, 8 

Shale,  red, 0»  6' 

42 


658  GEOLOGICAL   SURVEY    OF   PENNSYLVANIA. 


NO.    IV.    IN   MILL   HALL   GAP.  ( 

Sandstone,  reddish  brown, 75' 

Slate,  red,    ... 1' 

Sandstone,  red  and  gray,     200' 

Sandstone,  red, 9' 

Shale,  red, 4' 

Sandstone,  red, 2 

Slate,  red, 3 

Slate,  green, 1 

Slate,  red, 4 

Slate,  green, ...  2 

Sandstone,  red, 6' 

Sandstone,  red,  some  little  of  it  gray, 15' 

Sandstone,  red, 10' 

Slate,  gray, 2' 

Sandstone,  red, 18' 

Slate,  gray, 0'  5" 

Sandstone,  grayish  brown, 12' 

Shale,  red 0'  3" 

Sandstone,  brown, 20' 

Shale,  green, 0'  2" 

Sandstone,  brown, 4' 

tehale,  red, 1' 

Sandstone,  brown  and  gray,  and  concealed, 150' 

Sandstone,  gray,  and  concealed, 409 

Sandstone,  gray, 320' 

Sandstone,  gray,  and  slaty  sandstone, 440' 

2906'  6" 


In  Tyrone  gap,  according  to  Mr.  Sanders,  the  Medina 
white  measures  1068',  the  Medina  red  668',  and  the  Oneida 
1160'  making  a  total  of  2896'.  A  crush  fault  (apparently 
of  no  great  magnitude)  makes  the  statement  a  little  doubt- 
ful. It  is  evident  from  the  section  above  given,  that  the 
whole  formation  has  a  very  different  character  along  this  its 
westernmost  Bald  Eagle  outcrop,  from  its  character  along 
the  Jack's  mountain  outcrop,  25  miles  to  the  southeast. 
Many  of  the  beds  of  the  upper  Medina,  although  massive, 
have  a  red  color  and  might  justly  be  thrown  into  the  mid- 
dle division  (Medina  red). 

No.  IV  in  Mill  Hall  Gap. 

In  the  Bellefonte  gap  through  Bald  Eagle  mountain,  30 
miles  to  the  northeast  of  Tyrone  gap,  the  Medina  white 
may  be  said  to  have  a  thickness  of  400'  or  500'.  The  Me- 
dina red  here  consists  of  thin  bedded  gray  and  red  clay 
sandstones,  constituting  three  parts  of  the  whole  mass. 


660  GEOLOGICAL   SURVEY    OF   PENNSYLVANIA. 

~~ XcT 


Section  tine  J-%  OCTOM  Centre  tomukip. 


NO.    IV.    IN   THE   BEDFORD   GAPS.  661 

separated  by  and  alternating  with  beds  of  red,  gray  and 
greenish  shale.  In  the  uppermost  beds  have  been  found 
stem-like  vegetable  forms  (Scolithus  vertical-is)  which  are 
probably  the  casts  of  the  burrows  of  worms  going  down 
and  coming  up  in  the  sand'on  the  shore  of  the  sea  ;  its  total 
thickness  say  500'.  The  Oneida  is  here  again  divisible  into 
two  groups,  the  upper  (380'  thick)  composed  of  greenish  gray 
slightly  micaceous  sandstones,  specked  with  iron  ochre,  and 
separated  from  each  other  by  thin  layers  of  finely  lami- 
nated greenish  slates  ;  the  lower  (170'  thick)  a  mass  of  hard 
gray  sandstone  beds,  entirely  without  pebbles,  but  com- 
pletely covered  (where  exposed  to  the  weather)  with  yellow 
ochre  specks  produced  by  the  decomposition  of  iron  pyrites 
disseminated  through  the  whole  rock,  in  what  original  form 
has  not  been  investigated.  This  iron  speckled  aspect  of 
the  Oneida  division  of  Formation  No.  IV  is  characteristic 
of  it  throughout  the  central  region  of  the  State,  and  is  a 
peculiarity  which  marks  it  quite  as  plainly  as  the  flagstone 
slides  mark  the  Medina  upper  division. 

No.  IV  in  Williamsburg  Gap. 

In  the  gap'of  the  Juniata  river  through  Canoe  mountain 
in  Blair  county,  the  Medina  white  is  a  mass  of  white  and 
gray,  line  grained  heavy  sandstone  beds,  550'  thick.  The 
Medina  red  consists  of  softer,  reddish  brown,  clay  sand- 
stone beds,  a  few  beds  of  gray  sandstone,  and  a  great  many 
beds  of  red  shale,  subdividing  a  total  thickness  of  1050'. 
The  Oneida  is  as  usual  composed  of  massive  greenish  gray 
and  pinkish,  iron  speckled,  very  hard  sandstone  beds,  in 
all  500'  thick. 

No.  IV  in  the  Bedford  Gaps. 

In  Bedford  county  the  Medina  white,  still  making  the 
crests  of  the  mountain,  is  a  mass  of  almost  snow  white, 
line-grained,  very  hard  and  gritty  rocks,  860'  thick  in  the 
Yellow  creek  gap  through  Tussey  mountain,  but  growing 
thinner  southward,  so  that  it  is  only  300'  thick  in  the  Rays- 
town  Juniata  gap  through  Tussey  mountain,  near  Bedford, 


662  GEOLOGICAL   SURVEY    OF   PENNSYLVANIA. 


?'m(wy  ftudt  in,  Spring 


M?)  limed  fane 
<3>erry  Co 


NO.    IV.    IN   THE    BEDFORD    GAPS.          .  663 

and  200'  in  the  gap  through  Evitt's  mountain  (T2,  p.  91) ; 
no  fossils  but  the  sea  weed  Arthrophyous  being  seen  in 
it  at  any  exposure.  The  Medina  red  in  the  Bedford  dis- 
trict contains  comparatively  little  soft  shale  ;  its  beds  being 
chiefly  hard  fine-grained  red  sandstone  grits ;  containing 
innumerable  pellets  of  ochreous  clay,  which  when  exposed 
to  the  weather  are  dissolved  out,  leaving  the  rock  in  a 
curiously  pitted,  or  finely  honeycombed  condition.  Flat- 
tened lumps  of  red  clay  may  be  found  by  breaking  the 
rock  of  many  of  the  beds ;  and  these  suggest  an  explana- 
tion for  the  universal  iron  speckled  condition  of  the  Oneida 
beds.* 

As  for  the  Oneida  or  lower  division  of  No.  IV  in  Bed- 
ford county,  Dr.  R.  M.  S.  Jackson  of  the  First  Geological 
Survey  could  find  only  100'  of  beds  which  he  could  so  call 
in  the  gap  of  Will's  mountain  into  Millikin's  cove.  He 
suggested  that  the  lowe'r  part  of  it  might  be  concealed  by 
a  fault  along  the  western  edge  of  the  cove,  seeing  that  the 
strata  in  Buffalo  ridge  are  much  broken  and  turned  up  ver- 
tical. But  Professor  Stevenson,  in  report  T2  on  Bedford 
county,  could  not  recognize  any  Oneida  rocks  south  of 
Morrison's  cove.  Gray  sandstones  indeed  appear  in  Raver's 
creek  gap  through  Tussey,  on  the  Henrietta  road  in  Wood- 

*How  these  balls  of  clay  enclosed  in  fine  sand  originated  is  a  curious  ques- 
tion. It  is  also  a  matter  of  some  moment  to  get  any  answer  to  the  enquiry, 
whether  they  were  originally  round,  or  whether  they  were  deposited  in  their 
present  flat  shape.  For  if  they  were  originally  round  their  flattened  con- 
dition now  must  be  ascribed  to  pressure,  that  is,  to  the  consolidation  of  the 
Formation  No.  IV  under  the  burden  of  all  the  formations  up  to  the  Coal 
measures,  which  were  afterwards  laid  down  upon  it.  And  this  would  in- 
troduce a  subject  which  has  hardly  yet  received  attention  from  geologists, 
namely,  the  amount  of  compression  and  loss  of  bulk  vertically  which  all 
our  formations  have  suffered  in  the  lapse  ot  time,  partly  by  the  closer  pack- 
ing together  of  their  sand  and  mud  grains,  but  chiefly  from  drying  out  of 
the  original  sea  water  with  which  they  must  have  been  for  many  ages  com- 
pletely soaked  or  water  logged.  For  if  this  diminution  of  bulk  could  be 
shown  to  bear  a  considerable  proportion  to  the  original  thickness  of  sand 
and  mud  deposits,  the  calculation,  if  made  upon  a  sound  basis  of  fact, 
would  materially  modify  the. speculations  now  so  popular,  oftentimes  so 
rash,  and  in  all  cases  so  unsatisfactory,  respecting  the  mutations  of  the  sea 
level  in  various  geological  ages.  For  if  our  formations  in  drying  have  lost 
only  5  per  cent  of  their  thickness,  the  total  shrinkage  in  thickness  of  say 
40,000'  of  Palaeozoic  strata  would  amount  to  2000'. 


664  GEOLOGICAL   SURVEY    OF   PENNSYLVANIA. 


XCfif 


tcJ^irom  twc&ifoal ortion  o  foe 


g^TT-rE? 


K     /      I  L  L 


NO.    IV.    IN   THE  BEDFORD   GAPS.  665 

berry  township,  and  obscurely  at  two  places  on  Banning' s 
mountain  ;  but  Oneida  beds  are  certainly  absent  along  the 
Raystown  Juniata  in  both  Tussey  and  Evitts  mountain 
gaps.  In  fact  Oneida  sandstone  beds  were  seen  by  him  at 
no  locality  in  Bedford  county  more  than  35'  thick.  At  the 
two  places  last  mentioned  there  can  be  no  question  of  con- 
cealment by  faults,  for  the  top  layers  of  No.  Ill  are  regu- 
larly overlaid  by  Medina  red  or  brownish  red  shales  con- 
taining two  fossils  which  unmistakably  belong" to  that  divi- 
sion(Ambonyc7im  radiata  and  Rliynclionellacapax}2c&&  th» 
Hudson  river  slates  pass  without  any  break  of  sequence 
upward  into  Medina  shales  ;  so  that  there  can  be  no  doubt 
that  the  Oneida  formation  was  not  deposited  in  the  bed  of 
the  sea  in  this  locality,  even  in  the  condition  of  tine  sand. 
Yet  it  must  not  be  rashly  concluded  from  this  fact,  that 
dry  land  existed  here.  For  had  dry  land  existed  it  must 
have  been  land  of  No.  Ill  raised  above  the  sea  level  and 
afterwards  submerged  to  receive  the  deposit  of  No.  IV. 
But  the  moment  a  portion  of  sea  bottom  is  lifted  above 
water  level  rain-erosion  commences,  and  continues  until  re- 
submergence  ;  and  rain-erosion  must  leave  its  marks  in  the 
shape  of  hills  and  hollows  however  small  or  low.  Some 
break  in  the  continuity  of  the  deposit  must  take  pi  ace,  and 
must  remain  visible  ever  after  wherever  the  consolidated 
rock  strata  are  now  exposed  to  examination.  If  no  such 
break  appears  we  ma}7  be  sure  that  the  sea  bottom  has  not 
been  lifted  to  the  air.  Therefore  if  the  Oneida  format!  on, 
thick  and  pebbly  further  northeast,  grows  thinner  and  finer 
and  at  length  disappears  going  south,  allowing  the  Medina 
above  it  and  the  Hudson  river  below  it  to  come  quietly 
together,  it  is  certain  that  its  disappearance  is  really  and 
surely  due  to  the  fact  that  the  sediments  were  floated  fur- 
ther out  into  deep  water  according  to  their  fineness,  until 
at  length  the  finest  material  was  exhausted,  or,  mingled  with 
equally  fine  material  floated  in  from  other  directions. 


666  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 


Ml 


ylkil  Wafo^ap, 


(mdjie/ne,  reduc&lto  ft.  ivneaf 


NO.  IV.-  IN   CLINTON,  CENTRE   AND   LYCOMING.          667 

No.  IV  in  Clinton,  Centre  and  Ly coming. 

Following  the  Bald  Eagle  outcrop  of  IY  eastward  into 
Clinton  count}',  the  gaps  at  Lock  Haven,  Jersey  Shore  and 
Williamsport  furnish  sections  of  it  along  a  stretch  of  40 
miles. 

In  the  gap  at  Millhall,  near  Lock  Haven,  the  Medina 
upper  hard  massive  white,  gray  and  red  sandstones,  not  very 
well  exposed  measures  695'.  The  middle  division  of  in- 
terstratified  softer  sandstones  and  shales  measures  705'. 
Under  these  lie  hard  massive  sand  rocks  mostly  wrhite;  with 
a  few  beds  of  gray,  mottled  with  iron  rust,  188'.  Under 
these,  partly  concealed,  softer  sandstones  and  shales,  some 
of  them  red,  118'.  Under  these,  massive,  hard,  dark  gray 
and  greenish  gray,  iron  specked,  flinty  sandstones,  155'. 
Under  these  are  hard  and  massive  sandstones  with  con- 
cealed intervals  of  softer  rocks,  440' ;  which  makes  a  total 
thickness  of  2301'.  (G-4,  129).  It  is  evident  that  no  useful 
classification  of  the  beds  of  the  whole  formation  into  three 
divisions  can  be  made  out  of  the  mere  terms  of  this  sec- 
tion ;  but  it  will  be  shown  in  its  proper  place  that  where 
the  eye  of  the  geologist  is  at  fault,  the  hand  of  nature  works 
with  unerring  certainty,  and  carves  the  shape  of  the  mount- 
ain in  accordance  with  the  larger  groupings  of  the  hard  and 
massive  beds. 

In  the  gaps  issuing  from  Nippenose  valley  and  Mosquito 
valley  in  Lycoming  county  the  rocks  of  No.  IV  are  not 
well  exposed.  The  Medina  upper  hard  sandstone  is  esti- 
mated by  Mr.  Platt  at  only  100' ;  the  middle  red  division 
he  makes  1200' ;  arid  the  Oneida  hard  sand  rock  only  15' ; 
the  total  being  only  1375'  (G-2,  29).  The  contrast  between 
the  section  at  Mill  Hall  carefully  measured  by  Dr.  Chance 
and  this  roughly  estimated  section  of  Mr.  Platt  at  Jersey 
Shore  and  Williamsport  is  very  striking,  and  not  easily 
explained.  It  certainly  affords  no  safe  basis  for  generaliz- 
ing on  the  extent,  thickness  or  method  of  the  deposits. 


668 


GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 


NO.    IV.    ALONG   THE   GREAT    VALLEY.  669 

No.  IV  along  the  Great  Valley. 

Passing  now  to  the  long  outcrop  of  No.  IY,  which  bor- 
ders the  Great  Valley,  we  have,  first,  at  the  gap  of  the 
Susquehanna  above  Harrisburg  an  expression  of  the  for- 
mation totally  different  in  character  from  anything  observ- 
able in  the  outcrops  northwest  of  it  toward  the  Allegheny 
mountain.  The  Medina  upper  division  consists  of  a  series 
of  comparatively  thin  white  sandstone  beds,  alternating 
with  greenish  and  yellowish  slates  ;  some  reddish  sand- 
stones occurring  among  the  upper  layers  showing  impres- 
sion of  marine  plants  ;  altogether  making  only  300'  or  400'. 
The  absence  of  massiveness  here  in  the  upper  division  of 
No.  IV  is  quite  remarkable.  The  consequence  is  that  in- 
stead of  making  the  crest  of  the  mountain,  these  upper 
beds  crop  out  below  the  crest  on  the  southern  side,  over 
the  outcrop  of  the  Oneida ;  the  crest  being  made  by  the 
Iron  sandstone  of  the  Clinton  formation  No.  V.  that  is, 
in  Perry  county. 

The  Medina  middle  soft  red  division  of  No.  IV  is  here 
entirely  wanting ;  and  the  geologist  must  travel  along  the 
mountain  westward  toward  Franklin  county  to  find  it  again 
appearing  in  the  ridges  which  enclose  Path  Valley,  but  only 
feebly  developed.  Or  he  must  cross  Perry  county  north- 
westward to  find  it  coming  into  the  series  in  the  gaps  of 
the  Tuscarora  range.  If  he  continues  further  northward 
to  the  Shade  mountain,  Blue  Ridge  and  Black  Log  mount- 
ain gaps,  he  will  find  it  much  increased  in  thickness.  Be- 
yond these  to  the  northwest  are  the  sections  in  Jack's  mount- 
ain, Tussey  mountain,  and  the  Bald  Eagle  range,  which 
have  already  been  described,  where  it  attains  its  maximum 
thickness. 

No.  IV at  the  Susquehanna  Water  Gap. 
But,  in  the  Susquehanna  gap  above  Harrisburg  the  Oneida 
makes  a  great  mark  rising  steeply  to  the  top  of  mountain, 
along  which  its  rocky  outcrop  runs,  on  the  southern  slope. 
It  is  about  70'  thick,  40'  of  which  consists  of  white  sand- 
stone beds  containing  pebbles  ;  under  this  an  exceedingly 


670  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 


Xcvi. 


NO.    IV.    AT   THE    SUSQUEHANNA    WATER   GAP.  671 

coarse,  heterogeneous,  red  pudding-stone,  5'  thick.  Under 
this,  between  it  and  the  uppermost  layers  of  Hudson  River 
slate,  there  is  a  concealed  space  of  40'  or  60'.  How  much 
sliding  and  faulting  has  taken  place  in  this  interval,  or  how 
much  of  it  is  occupied  by  concealed  sandstones  cannot  be 
made  out.  The  wall  of  Oneida  exhibits  so  many  oblique 
slips  and  fault  joints  that  its  present  thickness  may  be  dif- 
ferent from  that  which  it  had  when  it  lay  horizontally  at 
the  bottom  of  the  sea.  The  most  interesting  feature  of 
this  famous  exposure  (apart  from  the  fact  already  men- 
tioned that  the  formation  is  here  pushed  over  the  vertical 
to  a  reversed  south  dip  of  70°)  is  the  five  foot  'coarse  pud- 
ding-stone. As  this  lies  at  or  near  the  bottom  of  No.  IV, 
and  more  or  less  directly  upon  the  slates  of  No.  Ill,  it  is 
certainly  an  indication  of  some  disturbance  having  taken 
place  in  some  other  and  perhaps  distant  district  of  the 
earth's  surface.  But  it  is  useless  to  speculate  upon  the 
origin  of  a  bed,  composed  of  pebbles  and  fragments  of  all 
kinds,  since  we  are  entirely  ignorant  of  the  depth  of  water 
which  then  and  there  existed,  of  the  nature  of  the  tide- 
runs  or  other  currents  which  could  transport  the  material, 
and  of  the  shape,  character  or  location  of  the  shore  lines 
which  bounded  the  then  water  basin. 

It  serves  no  good  purpose  to  suggest  that  we  have  here  a 
shingle  on  a  sea  beach.  It  would  be  equally  useless  to 
suggest  an  isolated  gravel  bank  in  the  midst  of  the  sea. 
Towards  the  west,  for  a  thousand  miles,  no  land  could  have 
existed  at  that  time  ;  nor  for  less  than  three  or  four  hun- 
dred miles  towards  the  north.  Our  South  mountains,  and 
in  fact  all  southeastern  Pennsylvania  was  then  not  only 
under  water,  but  covered  by  the  limestone  and  mud  for- 
mations No.  II  and  III.  If  the  great  mountain  mass  of 
North  Carolina  was  at  that  time  out  of  water,  which  is 
very  doubtful,  it  was  nearly  500  miles  distant  to  the  south. 
All  the  highlands  of  New  Jersey  were  at  that  time  sub- 
merged. The  Adirondack  mountains  in  northern  New 
York,  and  perhaps  parts  of  New  England,  may  possibly 
have  been  out  of  water,  and  possibly  the  Oneida  pebbles  were 
derived  from  those  sources  (but  were  certainly  subsequently 


672  OEOLOGICAL  SURVEY   OF  PENNSYLVANIA. 


#/     /  XCVH 

.  fffi'/fy  • 

of  If  4 

^-!>  M         i  .     .     '.I      •         h^ 


NO.    IV.    AT   THE   SCHUYLKILL   WATER  GAP.  673 

submerged,  as  the  Barnardston  fossils  show).  But  it  would 
defy  the  keenest  genius  to  make  out  the  case,  or  paint  the 
picture  of  the  transaction  in  colors  which  would  not  fade 
into  an  ^indistinguishable  gray  under  the  light  of  precise 
enquiry.  And  the  hopelessness  of  the  attempt  is  accented 
by  a  fact  which  seems  to  be  never  alluded  to  by  those  who 
generalize  on  such  subjects  ;  namely,  the  fact  that  our  for- 
mation No.  IV  while  being  deposited  in  the  Appalachian  sea 
of  America  was  at  the  same  time  being  deposited  in  the 
prolongation  of  that  sea  which  reached  Europe ;  being  re- 
cognized in  England  under  the  name  of  the  May  Hill  sand- 
stone ;  and  it  will  be  shown  in  discussing  Formation  No. 
VII  that  this  critical  fact  was  repeated  in  the  case  of  the 
OrisJcany  sandstone  which  was  deposited  in  the  United 
States  at  the  same  time  that  it  was  being  deposited  in 
France  ;  specimens  from  that  formation,  full  of  the  same  ani- 
mal forms  and  presenting  exactly  the  same  aspect,  having 
been  collected  from  the  outcrops  on  both  sides  of  the 
present  Atlantic. 

No.  I  Vat  the  Schuylkill  Water  Gap. 

A  topographical  contour  map  of  the  Schuylkill  Water 
Gap  at  Port  Clinton  made  by  Mr.  Chance,  with  careful 
measurements  of  the  five  groups  into  which  No.  IV  is  there 
subdivded,  gives  us  the  following  description  of  it : 

Three  prominent  ribs  of  sandrock  rise  vertically  from  the 
bed  of  the  river  to  the  north  slope  of  the  crest  of  the  mount- 
ain. No  distinction  can  be  made  in  the  Medina  between 
an  upper  white  and  a  lower  red  division.  At  the  top  rest 
90'  of  Upper  Medina  gray  sandstone  beds,  supported  by 
480'  of  iron  stained  shales ;  under  which  are  60'  of  Lower 
Medina  white  sandstone  beds  supported  by  600'  of  iron 
stained  shales  ;  and  at  the  bottom,  200'  of  Oneida  white 
sandstone  and  gravel  beds,  which  make  the  crest.* 

*This  is  a  rare  occurrence,  due  to  the  great  thickness  and  massiveness  of 
this  rib.     The  terrace  on  the  north  slope  is  made  by  the  outcrop  of  the  com- 
paratively thin  and   unsupported   Upper  Medina  rib.     See  cross-section, 
ng.  4,  plate  LIT,  on  p.  554  above. 
43 


674  GEOLOGICAL   SURVEY    OF   PENNSYLVANIA. 

At  this  interesting  locality  the  bottom  of  No.  IV  is  wholly 
separated  from  the  slates  of  No.  Ill  by  a  vertical  fault,  on 
the  north  side  of  which  the  sandstones  of  IV  rise  vertically 
into  the  air,  making  the  crest  and  north  slope  of  the  mount- 
ain. On  the  south  side  of  the  fault  the  slate  formation 
No.  Ill  is  sheared  off  like  a  cake  of  cheese,  the  edges  of 
the  slates  abutting  nearly  horizontally  square  against  the 
upturned  bottom  plate  of  Oneida  conglomerate.  It  is  im- 
possible to  affirm  that  it  is  actually  the  bottom  layer  of  the 
Oneida  ;  but  there  is  very  little  reason  to  doubt  it ;  seeing 
that  when  the  break  took  place,  and  the  whole  mass  of  No. 
IV  was  turned  up  at  right  angle,  it  is  probable  that  it  was 
turned  up  as  a  solid  mass  ;  and  that  the  lower  surface  of 
the  bottom  bed  acted  as  a  grinding  surf  ace  against  the  edges 
of  the  slates.  As  no  verbal  description  can  give  a  clear 
idea  ^of  this  phenomenon  the  section  is  presented  in  the 
figure  cited  in  the  last  footnote. 

The  Schuylkill  Water  Gap  is  50  miles  east  of  the  Sus- 
quehanna  water  gap  ;  and  in  these  50  miles  the  character  of 
the  formation  has  evidently  changed  in  an  extraordinary 
degree  ;  and  this  change  goes  on  becoming  more  and  more 
striking  eastward. 

No.  1 V  Lehigli   Water  Gap. 

At  the  Lehigh  Water  Gap  (25  miles  east  of  the  Schuyl- 
kill Water  Gap)  Dr.  Chance's  measured  section  gives  the 
following  details  :  Upper  sandstone  rib  85' ;  upper  ferru- 
ginous shales  180' ;  Middle  gray  sandstone  rib  70' ;  lower 
ferruginous  shales  330';  (total  Medina  665';)  Oneida  sand- 
stones, some  of  them  pebble-rocks,  290'  ;  Oneida  massive 
conglomerate  170' ;  (total  Oneida  460') ;  total  of  Forma- 
tion No.  IV,  1125'. 

We  see  that  the  pebble-rock,  which  at  the  Susquehanna 
gap  was  less  than  100'  thick  and  at  the  Schuylkill  gap  200', 
is  at  the  Lehigh  gap  nearly  500' ;  constituting  everywhere 
from  the  Susquehanna  to  the  Lehigh  the  central  rib  of  the 
mountain  and  sometimes  its  crest ;  while  the  middle  and 


NO.    IV.    AT   THE   DELAWARE   WATER   GAP.  675 

upper  sandstone  ribs  crop  out  as  terraces  and  benches 
along  the  northern  slope.* 

No.  IV  at  tlie  Delaware  Water  Gap. 

At  the  Delaware  Water  Gap  (25  miles. still  further  east) 
the  gradual  change  in  the  constitution  of  No.  IV  produces 
another  feature,  namely,  the  subdivision  of  the  Oneida  into 
three,  the  Medina  continuing  to  be  sub-divided  into  four. 
We  now  have  seven  distinct  subdivisions  of  the  formation 
No.  IV  as  follows  ;  Upyer  Medina  sandstone'rib  200' ;  upper 
ferruginous  shales  with  some  sandstone  beds  530' ;  Lower 
Medina  sandstone  rib  (here  a  white  conglomerate)  200' ; 
lower  ferruginous  shales  with  the  sandstone  beds  110' ; 
(total  Medina  1040') ;  Upper  Oneida  gray  sandstone  rib 
75' ;  intermediate  shales  with  sandstone  beds  240' ;  Lower 
Oneida  white  conglomerate  rib  210'  (total  Oneida  525'} ;  total 
thickness  of  No.  IV,  1564'.  f 

At  the  Lehigh  Water  Gap  there  is  some  doubt  about  the 
relation  of  the  bottom  bed  of  Oneida  to  the  slates  of  III  on 
which  it  rests  ;  but  at  the  Delaware  Water  Gap  there  is  no 
confusion  or  concealment  whatever ;  the  under  surface  of 
the  bottom  bed  of  the  lower  division  of  the  Oneida  con- 
glomerate rests  quietly  and  regularly  upon  the  uppermost 
sandy  slates  of  No.  III.  And,  what  is  more  important 

*  At  the  Lehigh  the  Upper  Medina  sandstone  makes  the  crest,  but  as  it  is 
comparatively  thin  the  crest  is  not  sharp  ;  and  as  it  is  supported  by  the  sec- 
ond rib,  with  only  170'  of  hard  shales  between  them,  the  two  ribs  act  like 
one,  and  as  if  235'  thick,  making  a  very  high  gently  rounded  crest  See 
figure  3,  LII,  page  554.  The  south  slope  of  the  mountain  becomes  steeper 
and  steeper  across  the  330'  of  hard  shales ;  and  becomes  35°  across  the 
290'  of  Oneida  sandstone  and  170'  of  Oneida  conglomerate,  more  than  two- 
thirds  of  the  way  down  to  the  foot  Here  the  slates  of  III  commence, 
and  the  slope  suddenly  becomes  gentle.  It  is  a  remarkable  contour  for  the 
mountain  of  IV,  well  worthy  of  careful  study.  The  outcrop  which  was  at 
the  very  crest  at  the  Schuylkill  is  here  at  the  Lehigh  nearly  at  the  south 
foot  of  tbe  mountain ;  not  on  account  of  dip,  but  on  account  of  the  differ- 
ent arrangement  of  the  rock  ribs  and  parting  shales  in  the  body  of  the 
mountain. 

t  Here  the  Oneida  upper  sand  rock  rib,  thin  as  it  is,  makes  the  crest,  be- 
cause it  is  so  closely  supported  (within  110')  by  the  huge  Lower  Medina 
sand  rock  rib,  and  by  the  very  sandy  character  of  the  Oneida  middle  shales. 
The  Oneida  conglomerate  makes  precipices  along  the  southern  slope  half 
way  down  the  mountain.  See  cross-section,  PI.  LXXX,  p.  638. 


676  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

still,  the  uppermost  beds  of  No.  Ill  are  here  so  sandy  as  to 
contain  thin  beds  of  sandstone,  showing  a  regular  proces- 
sion of  deposits,  and  a  sort  of  passage  from  the  slaty 
kind  (III)  to  the  coarser  sandy  and  gravelly  kind  (IV). 
And  yet  the  transition  is  in  fact  instantaneous  ;  as  if  avast 
quantity  of  grav.el  was  deposited  upon  a  level  sea  bottom 
of  dark  sandy  mud.  We  are  again  left  in  total  darkness 
as  to  the  cause  of  this  remarkable  operation.  But  after 
all,  it  is  no  more  extraordinary  than  the  way  the  May  Hill 
sandstone  of  England  rests  upon  the  shales  and  limestones 
of  lower  Silurian  Age. 

No.  IV  in  New  Jersey. 

The  Kittatinny  mountain  (called  Shawangunk  mountain) 
after  crossing  the  Delaware  river  at  the  Water  Gap  runs  on 
for  35  miles  to  the  north  corner  of  New  Jersey  at  Port 
Jervis.  Oneida  conglomerate  (Shawangunk  grit)  is  de- 
scribed in  the  Geology  of  New  Jersey  (1868,  p.  146)  as  a 
mass  measuring  (at  Otisville)  800'  or  900' thick,  composed  en- 
tirely of  beds  of  conglomerate  and  sandstone.  The  lower 
part  is  a  mass  of  quartz  pebbles,  from  one  quarter  to  three 
quarters  of  an  inch  in  diameter,  in  a  light  colored  quartz 
cement.  In  the  beds  above,  the  pebbles  become  smaller ; 
and  near  the  top  they  can  hardly  be  distinguished  from  the 
paste  in  which  they  are  imbedded,  the  whole  rock  being  a 
massive  compact  quartzite.  No  fossil  forms  have  been 
found.  Some  of  the  beds  contain  crystals  of  iron  pyrites 
which  have  yielded  to  chemical  assay  as  much  as  $11  of  gold 
to  the  ton,  This  occurs  at  the  bottom  of  the  formation  next 
the  slates  of  III.  The  lead  ore  veins  which  traverse  the 
rock  will  be  mentioned  directly. 

I  The  Medina  beds  outcrop  along  the  northern  slope  of  the 
mountain  descending  to  the  Delaware  river.  Their  esti- 
mated thickness  where  the  Erie  railroad  crosses  the  mount- 
ain east  of  Port  Jervis  is  800'.  The  two  formations  Me- 
dina and  Oneida  are  here  seen  to  pass  into  each  other  by 
a  series  of  alternations,  white  and  red,  fche  white  being 
Oneida,  the  red  Medina.  These  colors  strongly  contrast 
and  distinguish  the  two  formations.  The  Indians  called 


NO.    IV.    IN   NEW   YORK.  677 

the  mountain  "Shamgum"  the  white  rock.  It  is  evident 
from  the  change  of  color  that  the  sea  water  at  the  begin- 
ning of  Medina  time,  began  to  receive  large  accessions  of 
iron  ;  but  there  was  not  at  any  time  deposits  of  iron  ore.  The 
red  Medina  sandstones  are  interstratified  with  reddish 
shales ;  and  these  are  so  abundantly  traversed  by  trans- 
verse cleavage  planes  as  to  give  the  rock  in  some  places  the 
appearance  of  a  red  roofing  slate,  dipping  steeply  across 
the  bedplates  towards  the  southeast ;  but  the  coarser  and 
harder  brownish  red  sandstones  do  not  show  this  cleavage 
and  exhibit  the  true  northward  dip.  Occasionally  a  gray- 
ish green  shale  occurs.  The  bottom  Medina  beds  (next 
over  the  Oneida)  are  all  sandstone,  made  up  of  grains  of 
quartz,  some  of  them  containing  small  pebbles  of  white 
quartz,  interstratified  with  soft  shales ;  while  the  upper 
Medina  beds  are  nearly  all  reddish  shale  (much  split  by 
cross  cleavage)  interleaved  with  thick  red  and  grayish  sand- 
stone beds.  No  fossil  of  any  kind  except  a  sea  weed  has 
been  found ;  and  this  is  the  more  remarkable  because,  ex- 
cellently well  preserved  ripple  marks  are  common,  in  fact 
almost  universal. 

No.  IV  in  New   Yoik. 

The  Shawangunk  mountain  in  New  York  runs  on  north- 
east about  45  miles,  to  within  10  miles  of  the  Hudson,  and 
abruptly  ends  at  Rosendale  where  the  Rondout  and  Wai- 
kill  valleys  come  together.  Leaving  New  Jersey  "the  mount- 
ain has  a  crest  of  white  Oneida,  and  a  northern  slope  of 
red  Medina.  But  advancing  northeastward  the  Medina 
rocks  disappear  and  at  last  the  mountain  consists  exclu- 
sively of  Oneida  beds,  estimated  by  Mather  at  500'  running 
down  to  150'  and  even  as  thin  as  60'.  Some  red  beds  at  the 
top  would  seem  to  indicate  that  the  Medina  is  slighly  rep- 
resented ;  but  no  division  between  the  two  formations  is 
possible  ;  and  it  will  be  seen  hereafter  that  the  next  supe- 
rior formation  No.  V  thins  away  in  the  same  direction,  let- 
ting the  limestone  of  No.  VI  rest  upon  the  beds  of  No.  IV. 
These  details  respecting  the  geology  of  New  Jersey  and 
New  York  are  given  here  merely  for  the  purpose  of  show- 


678  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

ing  that  the  variations  in  Formation  No.  IV  throughout 
Pennsylvania  are  not  to  be  compared  for  magnitude  with 
its  variation  in  this  New  York  district.  The  mountain  in 
New  York  is  broken  by  great  cross-faults  which  traverse 
also  the  formations  above  it  and  below  it.  In  fact  the  re- 
gion bordering  the  Hudson  river  valley  has  been  shattered 
by  the  earth  movements  which  elevated  New  England;  and 
probably  it  is  to  the  greatest  of  these  faults  that  the  mount- 
ain owes  its  sudden  termination. 

Lead  ore  veins  in  No.  IV. 

The  remarkable  lead  veins  which  traverse  No.  IV  in  New 
York  are  among  the  consequences  of  the  shattered  condi- 
tion of  that  region.  Such  lead  veins  are  not  to  be  expected 
in  Pennsylvania  where  the  outcrop  mountains  of  No.  IV 
exhibit  few  cross  fractures.  In  the  early  settlement  of 
America,  Indians  and  hunters  searched  everywhere  for 
galena  to  furnish  themselves  with  bullets.  Hundreds  of 
traditions  of  Indian  lead  mines  have  been  handed  down, 
most  of  which  are  pure  fictions.  Indians  and  hunters  cer- 
tainly did  find  lead  in  certain  places  and  carefully  con- 
cealed their  discoveries  as  long  as  it  was  possible  to  do  so  ; 
but  probably  every  such  actual  lead  locality  is  now  known, 
and  are  few  in  comparison  with  the  great  number  of  fic- 
titious places.  Most,  if  not  all  of  the  actual  veins  have 
been  repeatedly  explored,  and  some  of  them  mined  at  con- 
siderable cost,  none  of  them  to  profit.  Forty  years  ago 
the  Ellenville  mine  at  the  base  of  the  Shawangunk  mount- 
ain, the  Ulster  mine  near  Red  Bridge  600  or  700'  up  the 
side  of  the  mountain,  and  the  Shawangunk  mines  near 
Wurtsboro  in  Sullivan  county,  N.  Y.,  600  or  700'  up  the 
mountain,  were  all  in  operation.  They  were  all  abandoned. 
In  the  Ellenville  mine  some  lead  and  zinc  were  obtained.  In 
the  Ulster  mine  masses  of  zinc,  lead,  copper,  and  iron 
pyrites  were  obtained.  In  the  Shcwangunk  mine  three 
masses  of  lead  ore  were  taken  out  weighing  from  800  to  1400 
pounds.  But  the  lead  veins  were  only  2'  or  3'  thick,  and 
the  ore  very  irregular.  The  abundance  of  finely  formed 


LEAD    ORE   VEINS   IN    NO.    IV.  679 

rock  crystals,  together  with  the  mixture  of  ores,  show  that 
they  were  deposited  from  solution  in  the  cracks  which  tra- 
versed the  region  after  it  had  been  shattered  by  the  great 
earth  movement  which  took  place  at  the  end  of  the  coal 
age.  It  is  idle  to  look  for  such  veins  in  No.  IV  in  middle 
Pennsylvania.  The  same  may  be  said  of  gold.  Although 
the  lower  beds  of  the  Oneida  are  largely  made  up  of  gold- 
bearing  quartz,  of  course  they  cannot  be  considered  in  any 
sense  ancient  glacial  placer  gravels ;  and  free  gold  has 
never  been  reported.  What  gold  exists  is  in  the  quartz 
pebble  itself.  It  is  perfectly  certain  that  no  gold  mining 
can  be  successful  in  any  of  the  mountains  of  No.  IY  in 
Pennsvlvania. 


680  GEOLOGICAL   SURVEY    OF   PENNSYLVANIA. 


J/ltJd-c/i  Spring  on  Sinking  Cr. 


Lin. 


Canoe  Mounkwn  terrace  and  linking  valley. 


TOPOGRAPHICAL  FEATURES  OF  MIDDLE  PENNA.    681 


CHAPTER  LII. 
Topograplucal  features  of  middle  Pennsylvania. 

The  facts  presented  in  the  foregoing  chapter  introduce 
the  subject  of  the  topography  of  the  central  belt  of  Penn- 
sylvania, especially  of  that  half  of  it  which  stretches  from 
the  Susquehanna  river  to  the  Maryland  state  line  :  for  this 
topography  has  for  its  most  striking  features  the  bold  ridge- 
outcrops  of  Formation  No.  IV. 

It  has  already  been  said  that  all  the  Pennsylvania  mount- 
ains from  the  North  mountain  of  the  Great  Valley  to  the 
Bald  Eagle  mountain  facing  the  Allegheny,  in  the  country 
west  of  the  Susquehanna  river  (with  only  three  excep- 
tions) are  mountains  of  Formation  No.  IV*. 

The  mountains  of  No.  IV  may  be  classified  in  three 
groups  of  zigzags,  so  complicated  in  their  shape  that  they 
can  only  be  described  by  a  map.  To  the  inhabitants  of  the 
various  counties  in  which  these  groups  stand  they  seem 
like  separate  mountains,  and  so  each  has  received  some 
separate  local  name. 

Names  of  Mountains  of  IV. 

The  number  of  local  names  is  very  great ;  the  prominent 
ends  of  the  zigzags  being  usually  named  after  some  settler, 
like  Parnell's  knob  and  Jordan's  knob  in  Franklin  county, 

*Two  of  these  exceptions  are  in  Perry  county,  namely;  Cove  mountain, 
ten  miles  and  Buffalo  mountain  twenty  miles  above  Harrisburg,  which  are 
mountains  of  No.  X,  and  belong  to  the  anthracite  region  of  eastern  Penn- 
sylvania. The  third  exception  is  that  of  Sideling  hill  and  Terrace  mountain 
in  Huntingdon  county,  surrounding  the  Broad  Top  coal  basin,  and  continu- 
ing under  various  local  names,  like  Harbor  mountain  and  Town  Hill,  into 
Maryland,  all  mountains  of  No.  X.  The  Broad  Top  mountain  enclosed  by 
them  is  made  by  No.  XII  capped  with  coal  measures.  A  fourth  exception 
might  be  mentioned  in  the  case  of  Great  and  Little  Savage  mountains,  in 
Somerset  county,  surrounding  the  Cumberland  coal  basin  in  Maryland  ;  but 
this  outcrop  of  No.  X  and  XII  is  nothing  but  a  zigzag  of  the  Allegheny 
mountain  and  belongs  properly  to  the  general  bituminous  coal  region  of 
•western  Pennsylvania. 


682  GEOLOGICAL   SURVEY    OF   PENNSYLVANIA. 

Sidney  knob  in  Fulton  county,  Jacks  mountain  in  Union 
county,  Tussey's  mountain,  Dunning' s  mountain  and 
Evitt's  mountain  in  Mifflin,  Blair  and  Bedford  counties. 
Others  have  been  named  after  the  animals  that  haunted 
them  in  early  times  ;  Bear  Meadow  mountain  in  eastern 
Huntingdon  ;  the  Buffalo  mountains  in  Union  ;  White  Deer 
and  Bald  Eagle  mountains  in  Ly coming.  Tuscarora  mount- 
ain, ranging  through  Juniata  county,  was  named  after  the 
principal  tribe  of  Indians  in  middle  Pennsylvania..  Stand- 
ing Stone  mountain  on  the  borders  of  Huntingdon  and 
Mifflin,  was  named  after  a  remarkable  monolith  or  solid 
stone  pillar  70'  high,  which  once  stood  on  the  bank  of  the 
Juniata,  at  the  mouth  of  the  creek,  near  the  present  town 
of  Huntingdon.  Around  it  the  grand  council  fire  of  the 
tribes  was  lighted.  Sometimes  a  name  was  repeated  ;  as, 
for  instance,  Path  Valley  mountain,  along  which  the  south- 
ern county  line  of  Centre  runs,  which  has  no  connection 
whatever  with  the  mountains  surrounding  Path  valley  in 
northern  Franklin  county.  Several  projecting  spurs  are 
called  Dividing  ridge,  or  Dividing  mountain,  because  they 
separate  two  parts  of  an  enclosed  valley.  German  settlers 
from  the  Rhine,  familiar  with  the  name  Siebengebirge, 
called  the  knot  of  ridges  between  Kishicoquillas  valley  and 
Brush  valley  the  Seven  mountains  ;  but  their  ends  toward 
the  Susquehanna,  in  Snyder  and  Union,  retained  their 
Indian  name  of  the  Buffalo  mountains  ;  a  proof  that  the 
bison  roamed  through  Pennsylvania,  when  the  beaver  made 
its  dams  on  many  of  our  streams,  and  herds  of  elk  ranged 
through  the  Allegheny  uplands. 

Three  groups  of  mountains  of  IV. 

1.  The  southernmost  group  of  mountains  of  IV  lies  be- 
tween the  North  mountain  of  Cumberland  and  Franklin 
and  the  Tuscarora  mountain  which  ends  at  the  Juniata  at 
Millers  town.  The  eastern  zigzags  are  represented  in  lig.  3, 
pi.  LXXIV,  p.  626.  They  enclose  the  fertile  valleys  of 
Perry  county,  Greenbrier,  Kennedy's.  Henry's,  Shafer's, 
Little  Illinois,  Sherman's,  and  Horse  valleys,  with  Path 
valley,  Burn's  valley,  and  Amberson  valley  in  Fulton 


THREE   GROUPS   OF    MOUNTAINS   OF   IV.  683 

county,  issuing  southward  upon  the  Great  Valley  at  Mer- 
cersburg.  This  group  is  extended  southward  through 
Fulton  as  Sidney  knob,  Tuscarora  mountain,  and  Cove 
mountain  surrounding  McConnellsburg  Cove  in  Fulton 
county,  into  Maryland.  It  includes  also  the  isolated  mount- 
ain which  ends  in  ParnelPs  knob  ;  and  the  two  mountains 
which  project  from  Maryland  toward  Mercersburg. 

2.  The  middle  group  of  mountains  of  IV.,  is  of  a  pecu- 
liar character.      Tt  resembles   three    long  narrow  canoes 
moored  side  by  side,  but  projecting  beyond  each  other ;  or 
rather  three  canoes  floating  bottom  up,  each  one  with  its 
bottom  knocked  out.     They  are  in  fact  the  eroded  tops  of 
three  long  closely  folded  anticlinal  arches  of  No.  IV,  sep- 
arated from  each  other  by  equally  long  narrow  and  closely 
compressed  basins  filled  with  Formation   No.  V.     (a)The 
southern  anticlinal,  having  West  Shade  mountain  for  its 
south  dipping  and  Black  Log  mountain  for  its  north  dip- 
ping outcrop,  extends  from  Fort  Littleton  on  the  Fulton 
county  line  to  within  ten  miles  of  the  Juriiata  at  Mifflin- 
town.     (5)The    middle    anticlinal,  called  Blue   ridge,  ex- 
tends from  the  Horse  Shoe  bend  of  the  Juniata  at  Newton 
Hamilton  to  the  Juniata  river  above  Mifflintown.     (c)The 
third  extends  from  the  Juniata  river  at  Lewis  town  to  within 
8   miles  of   Sslinsgrove,   on  the  Susquehanna,  in  Snyder 
county.      The   shape  and   arrangment   of   these    three  is 
shown  in  the  Vignette  Map  of  the  State  at  the  beginning  of 
this  volume.    Nothing  in  topography  is  more  beautifully 
symmetrical ;  nor  can  anything  illustrate  to  greater  advan- 
tage the  plication  of  the  formations  in  middle  Pennsylvania. 

3.  The  third  group  of  mountains  of  No.  IV  is  of  so  com- 
plicated a  character  as  to  defy  description  in  words,  and  is- 
therefore  given  in  outline  in  the  Vignette  just  mentioned. 
In  this  figure  a   black   line   represents   the    Medina  white 
sandstone  outcrop  which  everywhere  in  this  group,  extend- 
ing from  the  Susquehanna  at  Muncy  in  Ly  com  ing  county 
to  the  Maryland  line,  makes  the  mountain  crest;  while  the 
broken    line  alongside  of  it  represents  the   Oneida  gray 
sandstone  outcrop  which  everywhere  in  this  group  forms 
a   bold  terrace   on    the  mountain    flank.      The   southern 


684  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

border  of  this  group  is  the  noble  ridge  of  Jack's  mountain, 
which  borders  the  Lewistown  valley  on  the  north  and  for  50 
miles,  shuts  in  behind  it  the  fertile  Kishicoquillis  lime- 
stone valley,  bordered  on  the  northwest  by  the  Standing 
Stone  mountain,  and  on  the  north  by  the  Seven  mountains, 
which  spread  (northward)  as  Short  mountain,  Brush  mount- 
ain, Nittany  mountain,  Buffalo,  White  Deer  and  Bald 
Eagle  mountains  as  far  as  the  Williamsport  valley.  From 
the  western  end  of  the  Seven  mountains  projects  Tussey's 
mountain  which  runs  on  uninterruptedly  about  100  miles 
to  the  Maryland  line,  shutting  in  behind  it  the  fertile  lime- 
stone valleys  of  Penn's  creek,  Brush  creek,  Spruce  creek, 
Canoe  valley  and  Morrison's  cove.  The  Bald  Eagle  out- 
crop is  the  second  finest  in  the  State,  extending  along 
the  West  Branch  of  the  Susquehanna  for  30  miles,  from 
Muncy  to  Lock  Haven;  than  onward  along  the  Bald  Ea- 
gle creek  for  50  miles,  from  Lock  Haven  to  Tyrone  City; 
thence  onward  along  the  upper  Little  Juniata  for  15 
miles,  to  Frankstown;  then  returning  to  the  Little  Juniata 
(13  miles)  as  Brush  mountain  ;  bending  back  and  running 
south  (20  miles)  as  Canoe  mountain;  turning  and  running 
north  (6  miles)  toward  Hollidaysburg  as  Lock  mountain; 
resuming  its  south  course  as  D  tinning' s  mountain  (25  miles) 
it  bends  round  Dutch  corner  and  runs  south  (30  miles)  as 
Evitt's  mountain  into  Maryland.  Isolated  geographically 
from  this  outcrop  on  the  west  is  the  anticlinal  of  Will's 
mountain  and  Buffalo  Ridge,  extending  from  Bedford  (25 
miles)  to  the  Maryland  line. 

This  long  and  perhaps  tedious  enumeration  of  the  mount- 
ains of  IV  in  middle  Pennsylvania,  west  of  the  Susque- 
•hanna  river,  will  interest  the  people  of  that  part  of  the 
State  who  will  now  understand  the  geological  identity  of 
the  labyrinth  of  mountain  ridges  among  which  they  live. 
But  its  principal  value  arises  from  a  single  geological 
idea,  namely :  that  this  continuous  series  of  mountain 
crests  and  slopes  are  all  made  in  one  and  tthe  same  way, 
out  of  one  and  the  same  set  of  rocks,  exhibiting  every- 
where the  same  internal  constitution  and  differing  only,  (1) 
in  the  thickness  of  the  beds  or  groups  of  beds  at  one 


THREE   GROUPS   OF   MOUNTAINS   OF   IV.  685 

place  and  another,  as  has  been  fully  explained  in  the  last 
chapter ;  and  (2)  in  the  various  angles  to  the  horizon,  at 
which  their  strata  have  been  tilted  up. 

It  now  remains  to  show,  first,  why  these  mountains  some- 
times run  in  straight  lines  parallel  to  each  other  for  many 
miles;  secondly,  why  these  parallel  lines  sometimes  come 
together  at  both  ends,  as  do  the  gunwales  of  a  boat  at  the 
prow  and  stern;  thirdly,  why  in  other  districts  they  unite 
in  a  series  of  zigzags;  fourthly,  why  the  opposite  points  of 
such  a  series  of  zigzags  have  two  totally  different  charac- 
ters, one  long  and  sloping  gradually  into  the  plain,  the 
other  high,  sharp  and  abrupt,  projecting  like  a  knob  into 
the  air  ;  fifthly,  why  the  mountains  of  the  first  or  southern 
group  have  only  one  crest  and  two  slopes,  whereas  the 
mountains  of  the  middle  and  northern  groups  have  a  crest, 
a  long  continuous  slope  on  one  side,  and  a  bold  terrace  half 
way  up  the  slope  on  the  other  side;  sixthly,  why  the  Bald 
Eagle  mountain  in  Centre  county  has  two  crests  of  e'qual 
height  and  no  terrace  ;  seventhly,  why  the  terraces  are  cut 
through  at  short  and  regular  intervals  by  double  headed 
ravines;  and,  eighthly,  what  all  this  teaches  us  respecting  the 
great  rock  arches  which  once  rose  high  in  the  air,  but  have 
long  since  been  removed  and  swept  into  the  Atlantic,  furn- 
ishing collateral  evidence  that  the  surface  of  Pennsylva- 
nia is  still  being  slowly  but  continuously  fretted  down 
toward  the  level  of  the  sea. 

Before  taking  up  these  several  items  it  is  essen  tial  to  the  un- 
derstanding of  the  subject  that  the  reader  first  imagine  For- 
mation No.  IV  as  originally  lying  in  a  continuous  and 
nearly  horizontal  sheet,  deeply  buried  beneath  Formations 
V,  VI,  VII,  VIII,  IX,  X,  XI,  XII,  and  all  the  coal  meas- 
ures from  XIII  to  XVII.  He  must  then  picture  to  himself 
this  continuous  sheet  Formation  No.  IV,  with  all  the  forma- 
tions beneath  and  above  it  pressed  sideways  and  folded 
into  arches  and  troughs  also  under  western  and  northeastern 
Pennsylvania,  just  as  we  see  it  at  the  surface  in  middle 
Pennsylvania  west  of  the  Susquehanna.  Beneath  the 
anthracite  coal  basins  it  lies  at  various  depths  from 
10,000'  to  20,000';  but  between  the  basins  the  tops  of  its 


686  GEOLOGICAL    SURVEY    OF   PENNSYLVANIA. 

great  arches  approach  much  nearer  to  the  surface;  and  one 
of  them  actually  comes  to  the  present  surface  in  Montour's 
ridge  at  a  single  point  between  Danville  and  Sunbury, 
where,  in  a  ravine  descending  to  the  North  Branch  of  the 
Susquehanna,  37'  of  its  upper  beds  are  actually  exposed 
(See  G7,  p.  114).  The  mountainous  exhibition  of  it  at  the 
present  surface  west  of  the  Susquehanna  is  the  conse- 
quence of  a  gradual  upward  slope  of  the  whole  formation 
from  beneath  the  anthracite  country,  westward.  Going  west- 
ward the  arches  rise  first,  like  the  backs  of  whales  issuing 
from  the  surface  of  the  sea,  covered  with  soft  red  shales  of 
Formation  No.  V,  and  gradually  lifting  themselves  higher 
and  higher  into  the  air.  This  is  why  all  the  eastern  ends 
of  all  the  mountains  of  IV,  facing  the  Susquehanna  valley, 
have  one  and  the  same  character  of  long  gently  sloping 
mountain  noses. 

Parallelism  of  mountains  of  IV. 

A.  The  first  point  mentioned  above  is  the  parallelism  of 
the  mountains  of  IV.  This  parallelism  is  perhaps  the  most 
remarkable  feature  of  the  topography  of  middle  Pennsyl- 
vania. It  is  a  consequence  of  the  extraordinary  symmetrical 
shape  of  the  anticlinal  arches,  which  can  be  compared  to 
nothing  better  than  the  long  even  folds  in  heavy  woolen 
carpets  when  pushed  sidewise  over  a  floor.  The  formations 
composing  each  fold  may  be  well  explained  by  the  annual 
layers  of  wood  in  a  fallen  tree  trunk  which  arch  over  each 
other,  flat  along  the  top,  and  steeply  sloping  on  the  sides. 
Now  let  a  lumberman  adze  off  the  upper  part  of  such  a 
tree  trunk,  reducing  it  to  a  flat  surface,  he  will  expose 
the  edges  of  the  wood-layers  in  two  sets  of  parallel  lines, 
one  set  to  the  right  and  the  other  to  the  left ;  exactly 
corresponding  to  each  other ;  the  uppermost  layers  being 
the  farthest  apart,  and  the  lowest  layers  to  which  his  work 
reaches  occupying  a  middle  line  over  the  center  line  of 
the  log. 

This  it  precisely  what  nature  has  done  in  her  carpentry 
work  upon  the  long  prostrate  anticlinal  folds  of  the  Palaeo- 
zoic formations  ;  only  with  a  difference  of  tools.  Instead 


PARALLELISM   OF   MOUNTAINS    OF   IV.  687 

of  the  carpenter's  adze,  she  has  employed  frost,  the  thaw- 
ing heat  of  sunshine,  and  the  transporting  power  of  rain 
water.  With  these  tools  everlastingly  at  work  she  has 
planed  off  all  the  anticlinal  arches  of  middle  Pennsylvania 
nearly  to  a  common  level. 

But  the  difference  in  the  tools  employed  by  the  carpenter 
and  by  nature  makes  a  signal  difference  in  the  neatness  of 
work  done  in  the  two  cases.  The  adze  and  jack  plane  make 
no  account  of  variation  in  hardness  or  softness  of  the  several 
layers  of  wood  ;  the  edges  are  all  reduced  to  the  same 
plane  surface  ;  for  such  tools  have  no  selective  power  and 
care  nothing  for  either  the  resistance  or  the  compliance  of 
the  wood  which  they  remove.  But  the  tools  of  nature  ex- 
ercise a  kind  of  selective  judgment ;  or,  rather,  they  are 
sensitive  to  the  slightest  differences  of  hardness  or  softness 
in  the  rocks  upon  which  they  operate.  If  we  could  ascribe 
intelligence  to  nature  we  should  be  obliged  to  say,  that  she 
has  no  intention  to  produce  an  even  smooth  topography,  that 
is,  to  reduce  the  surface  of  the  State  to  a  perfectly  level 
plane.  Her  water  work  has  gone  further  into  the  softer 
rocks,  leaving  the  harder  outcrops  elevated,  and  the  hard- 
est and  most  massive  formations  standing  out  as  mountain 
ridges.  But  her  manner  of  working  has  been  essentially 
the  same  as  that  adopted  by  the  carpenter  who,  instead 
of  the  rapid  action  of  adze  and  plane,  should  content  him- 
self with  the  slow  and  tedious  operation  of  sandpaper, 
would  himself  produce  the  same  variety  of  parallel  ridges 
separated  by  creases  on  his  log  of  wood. 

The  parallelism  of  any  two  mountains  of  IV  on  two 
sides  of  any  anticlinal  which  extends  for  many  miles 
teaches  us  two  facts  : 

1.  We  learn  that  to  have  exact  parallelism  in  long  straight 
outcrops  the  crest  of  the  anticlinal  must  be  level  for  a  long 
distance  ;  for  it  is  evident  that  if  the  crest  of  the  anticlinal 
slope  upward  the  opposite  outcrops  must  diverge ;  if  it 
slope  downward  they  would  approach  each  other.  (2)  We 
learn  that  the  characteristic  form  of  our  anticlinal  arches 
cannot  belong  to  one  formation,  but  to  a  whole  and  very 
thick  series  of  formations,  all  folded  together.  This  can 


688  GEOLOGICAL   SURVEY    OF   PENNSYLVANIA. 

be  easily  understood  by  crumpling  two  substances  even 
as  different  in  thickness  as  silk  and  woolen ;  or  by  com- 
paring the  short  irregular  angular  crimpling  of  one  thin 
sheet  of  paper  with  the  ample  and  regular  fold  of  an  entire 
ream  of  paper.  The  Palaeozoic  formations,  lying  upon 
each  other  like  a  pile  of  Canada  blankets,  could  not  have 
been  pressed  by  the  earth  movement  into  any  arches  and 
troughs  not  of  magnificent  length,  height  and  depth,  and  of 
beautiful  symmetry.  Therefore  it  must  be  kept  in  mind 
that  we  are  dealing  not  with  a  few  layers  of  sandstone,  but 
with  40,000'  of  superimposed  sediments ;  and  that  when 
they  were  thrust  into  anticlinals  and  synclinals  they  all 
moved  together,  yielding  and  adjusting  themselves  to  each 
other,  especially  the  softer  to  the  harder,  but  yielding  to 
the  earth  movement  as  if  they  all  constituted  one  single 
formation. 

Convergence  of  mountains  of  IV. 

B.  The  second  point  to  be  noticed  seems  at  first  sight  a 
violation  of  the  principle  just  stated  ;  for  the  parallelism 
is  not  perfect  and  universal  ;  it  has  its  variations  ;  but  these 
variations,  when  explained,  will  be  seen  to  be  essential  to 
the  principle.  However  many  miles  two  mountains  of  IV 
may  run  parallel,  they  are  sure  sooner  or  later  to  approach 
and  unite  at  one  end  or  at  both  ends.  If  this  occurs  at 
both  ends  it  shows  that  the  anticlinal  fold  dies  down  in 
both  directions. 

The  student  of  our  geology  must  be  careful  to  make  a 
strong  distinction  in  his  mind  between  the  end  of  an  anti- 
clinal mountain  and  the  end  of  its  anticlinal  fold.  The 
mountain  comes  to  an  end  because  two  parallel  outcrop 
mountains  have  converged  and  sink  together  beneath  the 
present  surface.  But  the  anticlinal  fold  itself  keeps  on, 
carrying  the  formation  deeper  and  deeper  In  this  way  one 
formation  disappears  in  a  loop  at  the  surface  and  is  replaced 
by  another  further  on,  also  in  the  shape  of  a  loop.  Following 
the  axis  of  an  anticlinal  fold  we  have  say  first  an  arch  of  No 
II  in  the  valley  coming  to  a  point ;  then,  a  loop  of  No.  Ill, 
filling  up  the  end  of  the  valley;  then  a  loop  of  No.  IV  mak- 


MOUNTAIN    SPURS    OF    NO.    IV.  689 

ing  the  end  of  the  double  mountain;  on  the  outside  nose  of 
which  is  a  loop  of  No.  V  settling  into  the  plain ;  then  a 
loop  of  the  limestone  formation  No.  VI  descending  be- 
neath a  looped  ridge  of  Oriskany  sandstone  No.  VII ;  which 
descends  beneath  a  rolling  hill  country  of  No.  VIII,  ending 
in  a  grand  mountain  cove  of  red  sandstone  No.  IX 
capped  with  white  sandstone  X;  sinking  as  an  anticlinal 
nose  into  a  deep  loop  valley  of  the  red  shales  of  XI,  en- 
closed between  opposite  dipping  mountains  of  the  Conglom- 
erate XII,  separating  two  coal  basins. 

This  is  the  rule  in  all  cases  where  the  anticlinals  are  of 
the  first  order  of  magnitude. 

Mountain  spurs  of  No.  IV. 

C.  A  third  point  to  be  explained  is  the  production  of 
groups  of  mountain  zigzags.  This  requires  a  little  more 
strenuous  effort  of  the  imagination,  but  it  is  merely  a  com- 
plicated form  of  what  has  just  been  described.  When  the 
earth-movement  pressed  the  whole  series  of  Palaeozoic  for- 
mations into  folds  it  obeyed  a  thousand  variations  of  local 
stress  and  strain,  and  produced  therefore  not  merely  a  few 
grand  arches  of  the  first  order  one  or  two  hundred  miles  in 
length,  but  scores  of  folds  and  wrinkles  of  the  second  and 
third  order  of  far  inferior  height  and  length.  These  sub- 
ordinate folds  may  properly  be  considered  mere  parasites 
of  the  great  anticlinals  ;  they  are,  in  fact,  wrinkles  on  the 
descending  sides  of  the  grand  arches.  But  these  smaller 
arches  bring  the  outcrop  of  No.  IV  to  the  surface  and  re- 
turn it  underground  in  the  same  way,  but  more  rapidly 
and  locally.  They  produce  the  same  topography,  but  on  a 
smaller  scale.  Each  minor  fold  has  its  two  opposing 
outcrops  of  No.  IV,  coming  together  in  the  direction  in 
which  the  fold  dies  down.  Where  there  are  six  such  minor 
folds  side  by  side,  all  dying  down  in  one  direction  (say 
eastward,  as  in  Snyderand  Union  counties)  there  are  neces- 
sarily as  many  pairs  of  outcrop  mountains  of  IV  one  on 
each  side  of  each  fold,  producing  a  group  of  mountains  in 
zigzag,  with  six  points  in  one  direction,  and  as  many  in  the 
other.  Perhaps  the  best  way  to  comprehend  this  phenom- 
44 


690  GEOLOGICAL   SURVEY    OF   PENNSYLVANIA. 

enon,  would  be  to  take  a  sheet  of  corrugated  zinc  roofing, 
and  hold  it  slanting  in  a  basin  of  water.  The  edge  of  the 
water  will  make  similar  zigzags  against  the  surface  of 
the  tin.  The  more  erect  the  zinc  plate  is  held  the  shorter 
will  be  each  zizzag.  If  the  plate  be  held  nearly  flat,  one  end 
scarcely  below  the  water  and  the  other  scarcely  above  it, 
the  zigzags  will  be  long  and  sharp  pointed.  By  varying  the 
shape  of  the  bends  in  the  tin  plate,  that  is,  by  represent- 
ing anticlinals  and  synclinals  of  different  height,  breadth 
and  sharpness,  all  sorts  of  variations  in  the  zigzag  water 
line  can  be  got,  and  all  the  variations  of  our  No.  IV.  mount 
ain  zigzags  may  be  imitated. 

The  inelasticity  of  sand  and  mud  deposits  greatly  helps 
us  to  explain  their  present  folded  condition.  It  cannot  be 
too  of  ten  repeated,  that,  when  the  earth  movement  took  place 
the  whole  40,000'  of  Palaeozoic  formations  were  still  in  a 
moist  and  plastic  state.  Had  they  been  of  any  dry,  hard, 
elastic  material  they  would  have  been  bent  into  a  very  few 
perfectly  regular  folds,  each  formation  sliding  upon  the  sur- 
face of  the  one  beneath  it,  and  none  of  them  wrinkled. 
But  the  actual  mass  of  mud  and  sand  deposits  being  wet 
and  plastic,  was  necessarily,  when  thrown  into  folds  as  a 
whole,  compressed  into  ten  thousand  subordinate  folds  and 
wrinkles.  The  great  anticlinals  are  none  of  them  mathemat- 
ically perfect  vaults.  Their  opposite  sides  do  not  descend 
in  smooth  unvarying  curves  into  the  synclinal  troughs,  but 
wave  and  halt  and  pitch  irregularly  in  their  descent.  In 
geological  language,  the  dip  is  constantly  changing  to 
steeper  or  less  steep,  and  is  occasionally  reversed  ;  so  that 
on  the  long  slope  of  a  grand  anticlinal  there  are  always 
seen  to  be  one  or  more  subordinate  rolls'and  basins.  When 
the  bottom  of  the  long  anticlinal  slope  is  at  last  reached, 
we  are  in  the  middle  of  a  great  synclinal  basin,  and  begin 
to  ascend  the  long  wavy  slope  of  the  next  parallel  grand 
anticlinal.  Thus,  anticlinals  and  synclinals  virtually  oc- 
cupy the  same  ground  ;  each  anticlinal  measuring  in  breadth 
from  the  center  line  of  one  synclinal  across  the  arch  to  the 
center  line  of  the  next  synclinal  ;  each  synclinal  measur- 
ing in  breadth  from  the  crest  line  of  one  anticlinal  across 


MOUNTAIN   SPURS   OF   NO.    IV.  691 

to  the  crest  line  of  the  next.  From  the  very  nature  of  the 
curves  it  is  impossible  to  avoid  embarrassment  in  the  use 
of  these  terms  ;  and  it  is  unfortunate  that  the  double  mean- 
ing of  the  terms  employed  makes  their  representation  to 
the  mind  of  the  student  somewhat  vague.  If  it  were  pos- 
sible to  assume  points  half  way  down  1he  slope  we  might 
confine  the  term  anticlinal  to  the  arch  above  these  lines,  and 
the  term  synclinal  to  the  trough  below  these  lines  ;  but  in 
practice  this  cannot  be  done  ;  the  reader  must  exercise  his 
intellect  to  understand  the  facts  of  the  case,  and  keep  the 
distinction  between  the  upward  curves  or  arches  and  the 
downward  curves  or  troughs  as  distinctly  as  possible  be- 
fore his  mind's  eye.  Nothing  in  geology  is  simple  ;  noth- 
ing in  any  branch  of  science  is  easy  ;  to  understand  the 
true  nature  of  the  commonest  fact  of  the  world  requires  a 
strenuous  endeavor  of  the  judgment  and  the  imagination 
working  harmoniously  together.  And  this  is  especially 
true  in  geology,  most  of  its  facts  being  concealed  from  the 
naked  eye,  and  therefore  to  be  mentally  conceived,  and 
cautiously  reasoned  upon. 

Illustrations  of  the  complicated  character  of  the  anti- 
clinals  and  synclinals  of  No.  IV  are  given  in  fig.  1, pi. LX XIII, 
p.  624,  and  fig.  1,  pi.  XC,  p.  660.  See  also  pi.  XCV,  XCVI, 
XC  VII,  p.  670.  One  of  these  represents  a  series  of  sections  at 
intervals  apart  of  about  a  mile  across  the  Seven  mountains 
in  eastern  Huntingdon  county.  The  other  represents  a 
series  of  transverse  sections,  taken  at  greater  intervals 
across  the  main  anticlinal  of  Perry  county  which  crosses 
the  Susquehanna  and  runs  on  eastward  between  the  two 
arms  of  the  Schuylkill  county  anthracite  coal  basin— the 
Dauphin  basin  on  the  south  and  the  Wiconisco  basin  on 
the  north.  In  the  first  section  the  large  white  band  repre- 
sents the  folds  of  No.  IV,  mostly  along  the  plane  of  the 
present  surface.  In  the  second  section  No.  IV  is  every- 
where underground,  but  waved  in  the  same  manner ;  at 
the  sections  on  the  Juniata  and  Susquehanna  rivers  it  is 
covered  by  10,000'  or  15,000'  of  higher  formations. 

How  is  it  possible  then,  it  may  be  asked,  to  draw  cor- 
rectly the  shape  of  the  waves  of  the  deeply  buried  forma- 


692  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

tion.  The  answer  is,  that  they  can  be  geometrically  con- 
structed on  the  supposition  that  the  thickness  of  the  over- 
lying formations  remain  unchanged  throughout  the  region  ; 
at  least  that  any  irregularities  of  thickness  in  each  will 
practically  be  compensated  for  in  all  ;  and  that  the  dips 
observed  at  the  surface  will  give  a  good  practical  idea  of 
the  basins  and  arches  concealed  underground.  Nearer  than 
this  to  the  exact  truth  the  geologist  cannot  come,  unless  he 
employs  boring  tools,  which  is  of  course  not  to  be  thought 
of  for  such  great  depths.  Enough  is  plainly  observable  at 
the  surface  to  make  the  complicated  structure  of  middle 
Pennsylvania  completely  evident.  Wherever  formation 
No.  IV  comes  to  the  surface  in  mountain  ridges  a  thousand 
feet  high,  cut  through  to  their  bases  by  rivers  exposing  the 
strata,  there  the  character  of  the  anticlinals  of  the  first  order 
reveals  itself  with  admirable  clearness. 

The  difference  between  the  anticlinal  and  the  synclinal 
Knobs  of  IV. 

D.  The  fourth  question  must  now  be  answered  ;  why 
the  opposite  points  of  a  series  of  zigzag  mountains  of  No. 
IV  are  so  totally  different  in  shape  and  character? 

It  must  be  remembered  that  zigzags  of  No.  IV  are  pro- 
duced only  in  districts  where  the  plicated  formation  is  de- 
scending beneath  the  surface  eastward  and  consequently 
rising  into  bhe  air  westward — or  vice  versa.  If  now  we  im- 
agine such  a  set  of  zigzags  pulled  out  to  a  straight  line — 
in  other  words,  the  formation  not  waved,  but  still  descend- 
ing underground  in  one  direction  and  rising  into  the  air 
in  the  other — it  is  evident  that  in  the  descending  direc- 
tion, it  will  be  first  thinly  veneered  and  then  more  and 
more  thickly  covered  with  the  next  soft  red  shale  forma- 
tion No.  V.  In  the  other  direction  the  bare  sand -rock 
edges  will  be  abruptly  broken  off  in  a  line  of  cliffs,  from  un- 
derneath which  will  crop  out  the  soft  dark  shales  of  No.  Ill, 
making  a  steep  slope  from  the  foot  of  the  cliffs  down  to  the 
floor  of  the  valley  ;  and  in  the  valley  will  crop  out  the 
limestones  of  No!  II. 

Let  us  now  restore  the  zigzags.     The  only  difference  will 


ANTICLINAL    AND    SYNCLINAL    KNOBS    OF    IV.  693 

be,  that  instead  of  a  long  straight  range  of  cliffs  at  the 
crest  of  the  mountain  there  will  be  as  many  pointed  pro- 
jections as  there  are  zigzags,  each  projection  being  a  peak 
of  cliffs,  around  which  the  slope  of  underlying  slate  will 
bend.  Between  the  peaks,  and  running  up  into  the  zigzags, 
will  be  long  narrow  vales  of  slate,  No.  III. 

By  merely  looking  from  a  distance  at  the  shape  of  the 
eastern  and  western  ends  of  a  zigzag  mountain  of  IV  a 
geologist  can  tell  with  certainty  in  which  direction  the  an- 
ticlinals  which  make  the  zigzags  are  dying  down,  whether 
eastward  or  westward  ;  for  if  the  anticlinal  is  rising  west- 
ward and  descending  eastward,  the  east  end  of  the  mount- 
ains must  be  a  long  and  gentle  slope  covered  with  the  red 
shale  of  V  ;  and  the  west  end  of  the  mountain  must  be  a 
high  peak,  rocky  and  precipitious,  with  a  steep  slope  of 
slate  No.  Ill  into  a  valley  of  limestone  No.  II.  The  geolo- 
gical county  maps  furnish  plenty  of  examples  of  both 
kinds  ;  that  is  cases  where  the  rocky  point  is  at  the  west 
end  and  the  red  shale  slope  at  the  east  end  of  the  mountain; 
and  cases  where  the  rocky  point  is  at  the  east  end  and  the 
red  shale  slope  at  the  west  end  of  the  mountain.  To  assist 
the  reader  some  prominent  examples  may  be  pointed  out. 

Taking  the  southern  outcropof  No.  IV,  and  following  it 
from  the  Delaware  Water  Gap  west  ward,  Off  set  knob  appears 
as  a  synclinal  cliff-tipped  projection  looking  east,  while  the 
red  shale  end  of  the  zigzag  sloping  to  the  west  is  behind  the 
Wind  Gap.  The  zigzags.'of  the  little  Schuylkill  in  northern 
Berks  are  produced  by  ten  small  anticlinals  sinking  west- 
ward ;  consequently  it  is  the  eastern  points  of  the  zigzags 
which  have  the  Knob  cliffs.  In  Cumberland  county  the  two 
projections  of  the  North  mountain  into  the  Great  Val- 
ley are  towards  the  west ;  their  corresponding  red  shale 
zigzags  pointing  east  are  in  Perry  county.  Parnell's  knob 
and  Jordan's  knob  are  similar  synclinal  end  cliffs  pointing 
southward.  The  mountains  of  No.  IV  in  Perry  county, 
all  end  northeastward  in  long  slopes  of  red  shale  ;  their 
southwestern  ends,  projecting  into  Franklin  county,  are 
high  and  rocky.  The  triple  central  anticlinal  group  of  No. 
IV,  in  Shade,  Blue  and  Black  Log  mountains  die  down  at 


694  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

both  erids^  eastward  and  westward,  in  long  red  shale  slopes. 
So  does  Jack's  mountain  at  its  southwest  end  in  Hunting- 
don county,  and  its  northeast  end  in  Snyder  county.  The 
Buffalo.  White  Deer  mountains  slope  their  east  ends  be- 
neath the  red  shale  country  of  Union  county,  but  project 
westward  into  Kishicoquillis,  Penn's,  Brush  and  Nittany 
valleys  in  long  high  rocky  ridges,  with  ranges  of  cliffs  on 
each  side  and  broken  off  sharply  at  their  western  end.* 

Let  us  take  the  case  of  the  west  end  of  the  Nittany 
mountain  in  Centre  county.  Thousands  of  years  ago  the 
mountain  did  not  end  where  it  now  does,  but  extended  fur- 
ther west;  and  ages  before  that  old  time  it  extended  still  fur- 
ther west,  indeed  all  the  way  to  the  Juniata  river.  In  fact, 
Nittany  mountain  at  that  time  extended  to  and  was  merely 
an  extension  of  Canoe  mountain  in  Blair  county.  In  like 
manner  Brush  mountain  once  extended  westward  and 
united  with  Tussey  mountain.  Short  mountain  once  ran 
past  Aaronburg,  Millheim  and  Spring  Mills  to  join  Tussey 
mountain,  and  Egg  hill  was  part  of  it.  The  same  is  true  of 
the  two  beautiful  mountains  which  project  westward  into 
Kishacoquillis  valley.  There  was  once  a  time  when  the 
northern  knob  was  extended  to  meet  the  Standing  Stone 
mountain  atMilroy  ;  and  the  southern  knob  continued  on 
through  the  center  line  of  the  valley  towards  Reedsville. 

The  proper  way  to  express  the  fact,  then,  is  to  say  that 
the  cliff  knobs  of  No.  IV  show  how  far  the  destruction  of 
the  formation  by  sunshine,  frost  and  rain  in  the  synclinals 
up  to  the  present  time  has  gone.  In  each  instance  a  rocky 
knob  marks  the  exact  center  line  of  a  synclinal  basin  ascend- 
ing into  the  air  ;  and  on  the  other  hand  every  long  sloping 
red  shale  nose  of  a  mountain  of  No.  IV  marks  the.  exact 
center  line  of  an  anticlinal  arch  descending  into  the  under- 
ground. With  this  clue  in  hand  the  student  of  our  geology 

*The  term  broken  off,  is  that  which  an  artist  would  use,  or  a  mere  topo- 
grapher, or  railroad  engineer  ;  but  the  student  of  geology  ought  not  to  use 
it  if  he  can  find  any  substitute  for  it ;  for  there  is  no  geological  break  at  the 
ends  of  these  craggy  mountains.  Let  this  be  well  remembered  and  under- 
stood, for  otherwise  the  most  important  geological  idea  of  this  subject  will 
be  lost 


CRESTS,    SINGLE   AND   DOUBLE.  695 

cnn  find  his  way  through  the  hilly  labyrinth  of  middle 
Pennsylvania. 

The  elaboration  of  this  subject  has  been  intentionally 
carried  to  an  unusual  length  and  minuteness  in  the  foregoing 
pages,  because  the  laws  of  Structure  and  Erosion,  expressed 
on  so  grand  a  scale  by  the  outcrops  of  IV,  hold  good  in  the 
million  details  of  structure  and  erosion  on  a  smaller,  and 
on  the  smallest  scale,  in  all  the  other  Palaeozoic  formations, 
whether  regarded  in  mass,  in  groups  of  strata,  or  in  one 
single  layer.  Therefore  further  allusion  to  the  subject  will 
not  be  necessary  in  other  parts  of  this  book  beyond  occa- 
sional references  to  what  has  been  written  in  this  chapter. 

Crests,  single  and  double. 

E.  The  fifth  question  to  be  answered,  namely  :  Why 
the  southern  mountains  of  No.  IV  have  a  single  crest  and 
two  slopes,  while  the  northern  mountains  of  IV  have  but 
one  crest  and  a  terrace,  and  the  northernmost  of  all,  the 
Bald  Eagle,  two  crests  and  no  terrace,  can  be  easily  an- 
swered by  merely  pointing  to  the  fact,  stated  in  the  last 
chapter,  that  Formation  No.  IV  is  practically  a  single  sheet 
of  sandrock  at  the  southern  side  of  the  district,  and  a 
double  sheet  of  sandrock  at  the  northern  side  of  it.  To  state 
the  fact  more  precisely  : — In  the  Kittatinny  mountain  facing 
the  Great  Valley  the  Onieda  conglomerate,  the  bottom 
member  of  No.  IV,  is  coarser,  and  more  massive,  and  has 
resisted  erosion  best ;  while  the  Medina  strata  are  not  only 
comparatively  thin,  but  are  weakened  in  their  resistance  to 
erosion  by  large  intervals  of  softer  rocks  ;  so  that  the  whole 
northern  slope  has  been  worn  down  by  the  weather  without 
leaving  any  very  bold  terraces.  In  Perry,  Fulton  and 
Franklin  counties  the  Oneida  is  thin  and  has  a  mass  of 
harder  massive  rocks  above  it  which  make  the  top  of  the 
mountain,  with  a  pretty  regular  slope,  showing  slight  in- 
dications of  terraces.  But  in  the  middle  and  northern 
groups  of  mountains  of  IV  the  formation  consists  of  very 
massive  Oneida  at  the  bottom,  and  still  more  massive 
Medina  at  the  top,  the  two  separated  by  a  thick,  soft,  red 
mass.  The  Medina  therefore  makes  the  crest  of  the  mount- 


696  GEOLOGICAL   SURVEY    OF    PENNSYLVANIA. 

ain,  protected  by  the  softer  but  still  pretty  massive  middle 
division;  while  the  Oneida,  undermined  by  the  soft  sin  re 
ormation  of  No.  Ill  on  which  it  rests,  unable  to  rival  the 
Medina  in  its  resistance  to  the  weather,  and  therefore  in  its 
height,  is  necessarily  left  as  a  bold  terrace  on  the  outcrop 
slope,  about  two-thirds  as  high  as  the  crest  of  the  mount- 
ain. In  the  majority  of  cases  the  dip  of  the  formation  as 
a  whole,  whether  toward  the  south  or  toward  the  north, 
ranges  between  40°  and  60°  ;  so  that  the  Medina  upper 
slants  upward  through  the  mountain  as  its  central  rib  or 
plate  from  base  to  crest,  its  cliffs  overhanging  the  terrace 
of  Oneida  below. 

Difference  in  tlie  height  of  mountains  of  IV. 

F.  The  sixth  point  of  topographical  interest  to  be  ex- 
plained geologically  is  the  fact  of  the  Bald  Eagle  mountain 
having  two  crests  of  equal  height  and  no  terrace  ;  and  the 
additional  fact  that  this  mountain  with  two  crests  is  in- 
ferior in  height  to  the  opposite  Tussey  mountain,  which  has 
but  one  crest  and  a  terrace. 

In  Tussey  mountain  the  upper  Medina  is  thick  and  the 
Oneida  thin  ;  whereas  in  Bald  Eagle  mountain  the  upp^r 
Medina  and  the  Oneida  are  of  about  equal  thickness.  In 
Tussey  mountain  therefore  the  upper  Medina  makes  a 
high  crest  and  the  Oneida  a  terrace  ;  whereas  in  Bald 
Eagle  mountain  each  makes  a  separate  crest. 

The  inferior  height  of  the  Bald  Eagle  mountain  is  due  to 
the  fact  that  its  stratification  is  vertical. 

This  leads  us  to  the  consideration  of  another  law  of  topo- 
graphy, namely  that  (other  things  being  equal)  the  relative 
heights  of  mountains  is  determined  by  the  angle  at  which 
their  rocks  lie  to  the  horizon  ;  the  flatten  the  rocks  the 
higher  the  mountain;  the  steeper  the  dip  the  lower  the 
mountain  ;  the  steepest  dip  (90°)  makes  the  lowest  mount- 
ain. 

Surface  erosion,  that  is,  the  gradual  destruction  of 
strata  at  their  outcrops,  comes  about  as  a  double  process 
of  undermining,  and  toppling  down.  However  hard  and 
massive  a  formation  may  be,  and  therefore  in  itself  consti- 


KEEL    MOUNTAINS   OF   IV.  697 

tuted  to  resist  erosion,  its  powers  of  resistance  will  not  avail 
it,  if  it  lies,  at  a  moderate  slope,  upon  a  soft,  easily  weather- 
ing formation  underneath.  For,  as  the  underlying  softer 
rocks  are  removed  by  the  weather,  the  overlying,  massive, 
hard  rocks  tumble  down  in  blocks  separated  by  the  cleavage 
planes.  But  if  the  underlying  softer  formation  has  in  it 
numerous  interstratih'ed  beds  of  hard  rock,  its  own  rate  of 
erosion  is  made  slower  thereby,  and  the  overlying  forma- 
tion is  less  rapidly  undermined ;  consequently  its  height 
above  the  valleys  remains  always  relatively  greater. 

But  when  the  stratification  is  vertical,  a  lower  massive 
formation  (like  the  Oneida)  can  no  longer  give  a  protective 
support  to  an  upper  massive  formation  (like  the  upper  Me- 
dina}. Each  must  take  care  of  itself  separately.  It  is  a 
case  of  "divide  and  conquer."  The  sunshine,  frost  and 
rain  have  the  mountain  at  a  disadvantage,  and  reduce  its 
relative  height  to  a  secondary  rank.  This  interesting  law 
of  erosion  illustrates  itself  by  producing  various  features 
of  topography  which  are  inexplicable  to  minds  not  familiar 
with  the  character  of  the  war  which  is  perpetually  waged 
between  the  attacking  and  defending  parties,  the  elements 
of  erosion  on  the  one  side,  and  the  rock  constituents  on  the 
other. 

One  beautiful  illustration  of  the  way  in  which  the  rocks 
support  each  other  against  the  assault  of  the  weather  may 
be  found  in  the  synclinal  knobs  ;  for,  in  these  knobs  two 
outcrops  come  together  and  are  therefore  united  in  self-de- 
fense. In  addition  to  their  union  they  lie  horizontally 
along  the  center  line  of  the  basin.  The  anticlinal  knobs 
are  still  better  protected,  and  are  therefore  relatively  higher 
than  the  synclinal  knobs,  as  shown  in  the  sketch  of  Tussey 
mountain  as  seen  from  the  top  of  Terrace  mountain,  back  of 
Stonerstown,  in  Huntingdon  county  (Fig.  42,  p.  143,  of 
Manual  of  Coal). 

Keel  mountains  of  IV. 

Before  leaving  the  subject  of  the  crests  and  terraces  of 
No.  IV,  the  most  beautiful  phenomenon  in  the  topography 
of  middle  Pennsylvania  must  be  mentioned.  When  two 


GEOLOGICAL    SURVEY    OF    PENNSYLVANIA 

crests  converge  and  become  one.  projecting  as  a  single 
high  narrow  ridge,  between  two  limestone  vales,  and  end- 
ing in  a  synclinal  point,  their  two  terraces  curve  and  unite 
around  the  end  of  the  point..  If  the  curve  be  a  semi-circle, 
that  shows  that  the  synclinal  is  rising  rapidly  into  the  air. 
But  if  the  synclinal  rises  very  slowly  the  combined  terraces 
project  miles  beyond  the  end  of  the  crest,  and  then  come 
to  a  similar,  but  lower  synclinal  point  of  their  own  in  the 
limestone  valley.  This  is  the  case  with  the  two  synclinal 
terraced  mountains  at  the  east  end  of  Kishicoquillis  valley; 
and  it  is  the  case  with  Short  mountain,  Brush  mountain 
and  Nittany  mountain  in  Clinton  and  Centre  counties.  A 
spectator  regarding  these  mountains  from  the  floor  of  the 
valley,  sees  them  end  on  in  perspective,  or  as  if  in  section, 
arid  is  struck  with  surprise  at  their  symmetrical  shape,  re- 
sembling ships  that  have  been  turned  over  with  their  keels 
uppermost  (Figs. — ).  For  this  reason  they  received  from 
the  geologists  of  the  First  Survey  the  name  of  Keel  mount- 
ains of  IV. 

Ravine  system  of  IV. 

Gr.  The  seventh  and  last  item  of  topographical  interest 
relates  to  the  two  entirely  different  modes  in  which  the 
two  sides  of  a  terraced  mountain  of  IV  is  drained.  Tussey 
mountain,  for  example,  with  rocks  dipping  south  into 
Huntingdon  county,  and  outcrops  overlooking  northward 
the  great  limestone  valley  in  Centre.  On  the  Huntingdon 
side  there  is  a  long  slope  of  the  red  rocks  of  formation  No. 
V,  down  which  the  rainfall  delivers  itself  by  innumerable 
rivulets,  flowing  in  straight  and  shallow  channels  from  crest 
to  base.  On  the  other  or  Centre  county  side  the  uppermost 
slope  next  the  crest  is  a  sheet  of  fallen  fragments  of  upper 
Medina,  stopped  in  their  descent  by  the  Oneida  terrace,  the 
rainfall  cannot  deliver  its  waters  in  straight  lines  to  the  base  of 
the  mountain  on  account  of  the  massive  Oneida  strata  which 
out-crop  along  the  brow  of  the  terrace.  Consequently  it  cuts 
deep  ravines  sideways,  right  and  left,  in  the  soft  lower  Me- 
dina ;  and  these  ravines  meeting  in  pairs,  break  out  through 
the  Oneida  terrace  and  its  supporting  slates  of  III,  in  deep 


THE   ANTICLINAL    VAULTS    RESTORED.  699 

short  gorges  debouching  upon  the  limestone  valley.  The 
regularity  of  this  system  of  terrace  ravines  is  wonderful. 
The  ravines  are  all  alike  in  depth,  narrowness  and  steepness 
of  sides.  The  distance  from  ravine  to  ravine  is  almost  ex- 
actly the  same  from  one  end  of  the  mountain  to  the  other. 
Each  ravine  has  a  double  head,  one  to  the  right  the  other 
to  the  left,  its  branches  being  usually  of  equal  length.*  It 
is  impossible  to  repress  one's  admiration  at  this  flagrant 
proof,  first,  of  the  regularity  of  the  mountain  constitution  ; 
secondly,  of  the  equal  action  of  the  elements  upon  it  at  all 
points  ;  thirdly,  at  the  total  absence  of  violent,  paroxysmal  or 
irregular  conduct  in  the  processes  of  nature.  In  fact  it  may 
be  said,  that  a  student  who  wishes  to  investigate  the  subject 
of  Erosion,  that  is,  the  perpetual  destruction  of  the  earth's 
surface  by  the  surrounding  atmosphere,  and  the  ways  in 
which  this  destruction  is  accomplished,  could  not  do  bet- 
ter than  to  start  his  investigation  with  a  close  study  of  the 
terrace  ravines  of  No.  IV;  for  he  would  tind  out  in  his 
subsequent  experience  that  this  special  physical  phenome- 
non will  suggest  the  true  explanation  of  every  detail  of  the 
features  of  an  eroded  region. 

The  Anticlinal  vaults  restored. 

It  only  remains  to  say,  that  when  one  has  familiarized  him- 
self with  a  limestone  valley  shut  in  between  two  mountains 
of  IV,  with  their  even  rocky  crests,  and  ravine  cut  ter- 
races, the  strata  dipping  always  away  from  the  valley  in 
both  directions,  he  cannot  hesitate  to  drawing  the  conclu- 
sion, that  as  the  two  mountains  come  together  at  the  two 

*  See  also  the  map  of  the  south  flank  of  Jack's  mountain  in  Mifflin  county, 
given  on  page  plates  CIV,  CV,  CVI,  CVII  in  the  next  volume.  These 
plates  present  (on  a  scale  of  |)  the  eastern  half  of  the  unpublished  MS.  map  of 
the  south  flank  of  foot  hills  of  Jack's  mountain  from  Logan's  Gap  west  to 
McVeytown.  The  map  stretches  westward  to  Mount  Union  and  Jack's 
Narrows,  exhibiting  similar  features.  It  was  one  of  the  earliest  pieces  of 
topographical  work  of  the  Survey  (1874-75),  and  was  intended  to  illustrate 
Report  F  on  the  fossil  ore  belts  of  the  Lewistown  valley,  but  was  not  finished 
in  time  for  the  publication  ot  that  Report.  It  is  now  used  as  an  illustration 
in  the  chapters  on  the  Clinton  formation,  No.  V.  The  terrace  ravines  are 
shown  in  fig.  2,  plate  XIV,  p.  376 ;  in  plate  XVII,  p.  389;  plate  XXII,  p. 
400 ;  and  especially  by  the  great  map  sheets  of  Morrison's  Cove,  in  Report 
T,  Atlas. 


700 


MODEL   OF   PLICATIONS   OF   IV. 


ANTICLINAL    VAULTS   RESTORED.  701 

ends  of  the  valley,  so  their  strata  were  formerly  united  in 
the  air  above  in  an  immense  arch  or  vault  of  unbroken  sand- 
stone miles  high. 

This  effect  upon  the  judgment  and  imagination  com- 
bined is  irresistible  in  the  case  of  the  larger  valleys.  In 
the  case  of  a  long  and  narrow  anticlinal  valley  like  Black 
Log,  a  casual  visitor  might  not  be  led  to  this  conclusion, 
but  to  a  very  different  one.  His  first  impression  would 
probably  be  that  the  strip  of  limestone  land  along  the  center 
line  of  the  valley  had  been  pushed  up,  splintering  asunder 
the  overlying  slate  and  sandstone  formations  (III  and  IV), 
and  thrusting  the  broken  edges  of  the  fracture  to  the  right 
and  left.  In  the  beginning  of  the  present  century  such  was 
the  theory  of  the  Swiss  geologists,  Thurman,  Desor,  and 
others,  respecting  the  valley  formations  of  the  Jura  ;  and 
such  was  the  theory  respecting  all  the  mountains  of  the 
world  entertained  by  one  of  the  fathers  of  German  geology, 
Leopold  Yon  Buch.  Quite  recently  has  this  old  and  false 
conception  ceased  to  mingle  intimately  with  correcter  views 
in  many  minds.  The  principles  enunciated  in  this  chapter 
nevertheless  cannot  be  called  new,  for  they  were  fully  ex- 
plained and  sufficiently  illustrated  in  my  "Manual of  Coal 
and  its  Topography,"  published  in  1856,  and  in  Professor 
Rogers'  Geology  of  Pennsylvania  published  in  1858.  But 
even  then  they  were  not  new  ;  for  the  whole  subject  of  Pli- 
cation and  Erosion  was  placed  permanently  on  its  proper 
basis  of  demonstrated  theory  fifty  years  ago,  by  the  assis- 
tant geologists  of  the  First  Survey  of  Pennsylvania  ;  and 
both  facts  and  principles  were  known  and  used  by  Whelp- 
ley,  Henderson,  Jackson  and  McKinley  in  their  daily  field 
work,  and  in  the  construction  of  the  maps  and  sections  with 
which  they  illustrated  and  embellished  their  reports.  It  has 
been  recently  stated  as  a  new  discovery  that  there  is  an  or- 
ganic connection  between  anticlinal  folds  and  down-throw 
and  up-throw  faults  ;  and  the  credit  of  this  supposed  dis- 
covery has  been  given  to  the  able  geologists  of  the  United 
States  Survey  in  the  Rocky  mountain  regions.  But  like 
other  applications  of  principle  to  fact  in  this  whole  sub- 
ject, the  passage  of  arches  into  f units  was  so  fally  explained 


MODEL    OF   PLICATIONS   OF   XO.    IV. 


THE    ANTICLINAL    VAULTS    RESTORED.  703 

by  the  early  surveys  of  Pennsylvania  and  Virginia  that 
nothing  essentially  new  or  different  has  in  recent  years  been 
added  to  it,  except  in  the  one  point  of  the  distance  to 
which  Onerthrust  faults  have  been  carried  horizontally,  as 
in  Western  Scotland,  the  Alps,  and  the  Rocky  mountains. 

Model  of  the  upper  surface  of  the  Medina,  No.  IV,  after 
its  plication  and  before  its  erosion. 

Page  plates  LVII,  LVIII  were  made  from  two  photo- 
graphs of  the  surface  of  a  model  constructed  by  me  in  1886, 
to  show  the  crumpled  geology  of  Middle  Pennsylvania,  as 
contrasted  with  the  gently  waved  structure  of  the  whole 
country  back  of  the  Allegheny  mountain  (the  western  and 
the  northern  counties)  and  the  almost  wholly  undisturbed 
condition  of  things  in  the  Pocono  and  Catskill  mountain 
region  on  both  sides  of  the  upper  Delaware  river.* 

*I  planned  this  model  In  1841  while  I  was  drawing  the  thirteen  long  sec- 
tions across  the  State  which  Prof.  H.  D.  Rogers  published  in  1858  along 
the  bottom  border  of  my  State  Map.  But  the  data  obtained  by  the  First 
Survey  did  not  seem  to  me  sufficiently  precise.  When  the  Second  Survey 
was  organized  in  1874  I  waited  until  the  surveys  of  the  middle  counties  could 
be  mapped,  with  local  sections  abundant  enough  to  cover  the  whole  area.  By 
1886  most  of  the  county  maps  had  been  published  on  a  scale  of  two  miles  to 
the  inch,  with  well-defined  limits  to  the  formations.  In  1885 1  published,  in 
Report  X,  count3r  maps  of  the  whole  State  on  the  scale  of  six  miles  to  an 
inch.  Of  these  I  selected  enough  to  cover  a  sufficient  area,  and  afford  a  sat- 
isfactory basis  for  a  model. 

There  are  but  two  methods  of  making  such  a  model ;  one  is  to  cut  it  down 
to  fixed  limits  ;  the  other  is  to  build  it  up  from  a  base  plane.  With  hypso- 
metrically  surveyed  contour  line  maps  of  the  surface  the  simplest  method 
is  to  jig  out  the  contours  in  paper,  card  board,  or  veneer  wood  ;  pile  them  on 
one  another ;  paste,  glue  or  tack  them  fast ;  cover  them  with  wax  ;  tool  the 
whole  to  a  smooth  surface  ;  cast  a  mold  ;  from  the  mold  cast  a  positive  ;  and 
finally  tool  it  to  satisfaction.  In  1856  I  made  such  a  model  of  the  Johnstown 
district  in  Cambria  and  Somerset  counties,  from  Edward  Smith's  contour 
map  of  the  country  for  the  Pennsylvania  railroad.  Sheets  of  paper  repre- 
senting Smith's  10-foot  contours  were  scissored  by  myself  and  my  wife  in 
the  evenings,  and  the  result  was  a  very  beautiful  model,  the  photograph  of 
which  was  made  into  a  relief  plate  and  published  in  1877  in  Report  H2,  page 
92.  But  it  was  a  tedious  and  laborious  job. 

Most  of  the  models  of  the  Second  Survey  have  been  made  in  this  manner, 
chiefly  by  Mr.  E.  B.  Harden,  topographical  assistant  of  the  survey.  The 
process  requires  nothing  but  accurate,  patient  labor. 

Another  method  is  to  construct  cross  sections  at  various  intervals  across 
the  area  to  be  modeled,  and  as  nearly  as  possible  at  right  angles  to  the 


704  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

The  model  is  limited  on  the  south  by  the  Maryland  and 
YV.  Virginia  state  line,  from  Adams  county  to  Fayette 
county  ;  on  the  southeast  by  the  range  of  the  South  mount- 
ains, the  Reading  and  Durham  hills,  and  the  Highlands  of 
New  Jersey  and  New  York  :  its  lower  left  hand  corner  is 

strike ;  draw  them  on  slips  of  paper,  wood,  lead,  zinc,  or  block  tin  ;  leave 
the  bases  of  the  strips  straight  cut  the  upper  section  surface  lines  ;  arrange 
the  strips  on  a  solid  basis  at  their  true  geographical  distances  from  one  an- 
other ;  nil  in  the  intervals  with  plaster  or  wax ;  and  tool  the  whole  model 
to  the  upper  section  lines.  This,  however,  requires  the  eye  and  hand  of  an 
artist ;  but  it  has  the  advantage  of  a  more  delicate  and  truthful  treatment  of 
the  intervals  between  the  section  slips,  governed  and  guided  by  the  topo- 
graphical features  of  the  survey  map  of  the  region  modeled.  The  geological 
artisst  is  not  encumbered  with  the  solid  plates  of  the  first  method,  and  can 
work  freely  in  correcting  and  bringing  out  to  clear  view  the  characteristic  fea- 
tures of  the  topography,  provided  he  has  studied  them  himself  and  appre- 
ciates their  character.  This  method  can  safely  be  adopted  only  by  the  geolo- 
gist who  has  done  the  field  work  himself,  and  it  cannot  be  safely  delegated 
to  office  hands. 

I  used  a  modification  of  this  process  for  a  model  of  Morrison's  Cove,  in 
1853,  for  the  Pennsylvania  Railroad  Company,  to  show  the  iron  ore  horizons. 
I  took  prisms  of  soft  wood  18"  long,  3"  wide  and  2"  thick,  and  drew  on  their 
contiguous  sides  duplicate  geological  sections  ;  then  tooled  down  the  surface 
of  each  block.  When  laid  side  by  side  in  a  series,  the  surface  of  the  country 
was  exhibited  topographically.  By  separating  the  blocks  the  geological 
structure  on  the  cross  lines  between  block  and  block  could  be  consulted. 
The  surface  of  the  whole  series  was  painted  to  show  the  outcrop  belts. 

In  constructing  other  local  geological  models  I  have  found  this  method 
much  more  satisfactory  than  the  method  of  jigging  and  building  up. 

But  in  making  my  model  of  the  corrugations  of  middle  Pennsylvania  I 
was  compelled  to  use  the  method  first  described,  on  account  of  its  rapidity 
of  execution,  since  I  accomplished  in  six  weeks  what  would  probably  have 
cost  me  as  many  months  of  labor  by  the  method  of  cross  sections.  A  descrip- 
tion of  the  details  will  be  useful  to  geologists  who  are  not  familiar  with 
such  work. 

I  first  laid  the  colored  geological  Hand  Atlas  county  maps  together  to 
cover  the  field.  I  divided  the  field  into  four  parts  by  equal  N.  W.  interval 
lines  to  make  four  models  which  could  afterwards  be  cast  in  one.  Then  I 
drew  on  tracing  paper  the  outcrop  limits  of  the  formations  above  and  below 
the  Medina.  The  known  thickness  of  the  overlying  formations  gave  the 
depth  of  the  top  of  Medina  in  reference  to  sea  level.  Sea  level  was  the  nor- 
mal datum  of  the  model.  The  deepest  sea  level  of  the  top  of  the  Medina  was 
adopted  as  the  plane  base  of  the  model.  The  contour  lines  of  the  top  of  the 
Medina  were  determined  by  measuring  down  from  the  contour  limit  lines 
of  all  the  upper  formations.  Account  had  to  be  taken  of  the  known  thin- 
ning of  all  the  formations  northwards  and  westwards.  The  columnar  sec- 
tions governed  the  whole  process.  When  the  dips  were  steeper  a  reduction 
for  angle  had  to  be  made.  When  the  dips  were  gentle,  no  such  reduction 
was  necessary,  as  the  error  would  be  trivial.  In  the  end  I  obtained  an  un- 


UPPER   SURFACE   OF   MEDINA,  NO.  IV.  705 

in  Butler  county.  The  area  exhibited  is  about  230  miles 
long  by  130  broad.  The  scale  adopted  was  that  of  the 
small  county  maps  in  the  Hand  Atlas,  Report  X,  6  miles  to 
the  inch.  The  photograph  plates  reduce  the  scale  to  about 
33  miles  to  the  inch. 

It  was  essential  to  my  design  of  a  true  representation  of 
the  amount  of  plication  that  the  vertical  scale  of  relief 
should  be  the  same  as  the  horizontal  geographical  scale,  a 
principle  which  has  been  kept  in  view  in  the  construction 
of  all  cross  sections  published  in  the  Reports  of  the  Survey 
from  the  beginning.  No  matter  how  gentle  the  gradients 
they  must  conform  to  nature.  The  human  eye  is  a  perfectly 
competent  instrument  and  may  be  safely  trusted  to  notice 
and  estimate  accidents  of  relief  of  the  minutest  size  and 
most  delicate  variation  from  the  horizontal.  Nothing 
should  be  left  to  the  imagination.  Science  gains  nothing 
and  loses  much  by  any  exaggeration  under  any  circum- 
stances. There  is  no  such  thing  as  meeting  nature  half- 
way. Absolute  truth  in  relationships  is  as  necessary  for 
knowledge  as  correct  understanding  of  individual  things. 

For  plate  .L/VII  the  model  was  photographed  upside 
down,  with  a  slant  light  from  the  left  (S.  E.)  to  bring  out 
the  master  feature  of  the  structure,  the  Nittany  Valley  or 
Bald  Eagle  Mountain  Anticlinal,  which  occupies  in  crescent 
shape  the  center  of  the  area.  As  its  western  slope  is  very 
steep,  in  parts  vertical,  the  shadow  cast  is  heavy.  The 
prevalence  of  steeper  western  than  eastern  slopes  in  the 
case  of  most  of  the  other  anticlinals  is  marked  on  this 
plate  ;  especially  in  the  case  of  the  three  great  anticlinals 
which  lap  each  other  and  make  the  southern  border  of  the 
First  Anthracite  coal  field  from  Mauch  Chunk,  Tamaqua 
and  Pottsville  to  the  end  of  the  Dauphin  county  basin,  and 
so  onwards  through  Perry  and  Cumberland  county  into 
Franklin.  The  echelon  arrangement  of  this  combined  over- 

derground  contour  line  map  of  the  top  of  the  Medina  approximately  correct. 
It  was  only  necessary  afterwards  to  take  the  curves  of  dip  in  the  air  to  re- 
store the  aticlinals  destroyed  by  erosion,  and  the  model  was  complete.  The 
scale  being  6  miles  to  the  inch  horizontal  and  vertical  alike,  an  inch  of  height 
represents  31,680  feet. 
45 


706  GEOLOGICAL   SURVEY    OF   PENNSYLVANIA. 

thrown  anticlinal  is  very  remarkable  and  could  be  well  ex- 
hibited only  by  a  model  seen  under  a  S.  E.  slant  light. 

For  Plate  LVIII  the  model  was  photographed  erect  under 
a  slant  light  from  the  left  (N.  W.)  to  bring  out  other  fea- 
tures ;  especially  the  Anthracite  synclinals  and  their  con- 
tinuation southwestward  into  Maryland.  The  reader  will 
notice  that  from  Carbondale  (an  inch  below  the  center  of 
the  top  line  of  the  plate)  there  is  a  continuous  synclinal 
trough,  much  crumpled  in  the  center  of  the  plate  (Seven 
Mountains),  with  a  local  deep  hole  (Broad  Top),  shallowing 
into  Maryland.  It  will  be  noticed  that  the  Nescopec  anti- 
clinal of  Luzerne  county,  which  separates  the  Middle  and 
Northern  Anthracite  basins,  keeps  on  as  the  anticlinal  of 
Kishicoquillis  valley  and  Jack's  mountain,  dying  down  in 
Bedford  county. 

The  crescent  shape  of  the  corrugations  of  the  region  is 
visibly  explained  by  Plate  LVII,  which  brings  into  relief 
the  great  Nittany  anticlinal.  By  taking  its  crescent  as  an 
arc  of  a  great  circle,  and  drawing  a  radius  from  its  middle 
and  highest  point  (in  Centre  county),  southeastward  towards 
the  head  of  Chesapeake  bay,  it  will  be  made  evident  that 
along  that  radius  was  exerted  the  maximum  force  of  the 
horizontal  thrust  which  displaced  the  formations  and  piled 
them  together  in  folds.  By  laying  a  string  upon  the  model 
along  this  radial  line,  I  found  that  the  forward  thrust  of 
the  earth  crust  (so  far  as  the  Medina  can  indicate  it)  was  at 
least  40  miles.  It  is  worth  noting  also  that  the  Bald  Eagle 
Mountain  and  Black  Log  Mountain  faults  are  southwest  of 
said  radius,  and  have  their  right  hand  (N.  E.)  side  walls 
thrust  forward. 

Conformity  of  IV  upon  111.   \ 

1  have  expressed  my  opinion  on  this  interesting  geolog- 
ical topic  in  the  third  report  on  Lehigh  and  Northampton 
Counties,  D3,  Vol.  1,  1883,  pp.  32  to  35. 

A  non-conformity  of  the  Oneida  conglomerate,  No.  IVa, 
upon  the  top  of  the  Hudson  river  slates,  No.  Ill,  has  fre- 
quently been  asserted.  In  Pennsylvania  they  appear  to  be 
quite  conformable ;  no  erosion  of  the  uppermost  slates  of 


CONFORMITY   OF   IV   UPON   III.  707 

III  previous  to  the  deposit  of  the  conglomerates  and  sand- 
stones of  IV  having  been  noticed. 

At  the  Rondout  quarries  in  New  York  the  Helderberg 
limestones  seem  to  lie  upon  the  upturned  edges  of  the  Hud- 
son river  slate.  At  Catskill  village  they  appear  to  lie  di- 
rectly but  conformably  upon  the  slate. 

Mr.  Davis  in  his  recent  beautiful  memoir  (quoted  in  G6) 
states  in  his  text  and  shows  in  his  sections  an  apparently 
perfect  conformdbility  of  the  Lower  Helderberg  limestones 
(JVo.  VI)  upon  Hudson  river  sandstones  and  slates  (No. 
Ill]  in  the  vale  of  the  Catskill,  a  mile  or  two  back  from  the 
Hudson  river;  with  an  apparent  absence  of  the  Clinton  ( V) 
and  Medina  and  Oneida  (IV)  which  usually  intervene. 

Although  the  district  of  country  in  which  these  phenom- 
ena present  themselves  is  small,  yet,  out  of  these  local  phe- 
nomena an  hypothesis  has  been  framed  and  made  to  apply 
to  a  thousand  miles  of  the  continent,  viz  :  that  the  Hudson 
river  age  closed  not  merely  with  a  disturbance  of  the  re- 
lations of  land  to  sea,  resulting  in  the  shifting  of  coasts  and 
the  deposit  of  gravels  and  sands  (which  might  be  easily 
admitted),  but  with  huge  elevations  and  upturnings  of  the 
sea-bed,  extensive  erosion,  and  the  deposit  of  horizontal 
upon  vertical  strata.* 

*  S.  A.  Miller  in  his  N.  A.  Geol.  and  Pal.  1889,  p.  48,  says  :  « It  always  rests 
unconformably  upon  the  Hudson  river  group,  and  bears  the  internal  evi- 
dence of  having  been  derived  from  land  immediately  north  and  east,  and  of 
having  been  deposited  in  shallow  water,  subject  to  waves  and  currents  which 
transported  only  short  distances.  The  conglomerate  indicates  a  shore-line 
and  rapid  deposition,  and  is  almost  non-fossiliferous,  although  a  few  frag- 
ments of  fucoids  and  shells,  generally  too  imperfect  for  definition,  ba^e  been 
found  in  it  The  sandstone  too  bears  the  evidence  of  having  been  deposited 
near  the  land  in  shallow  water,  not  only  in  wave-lines,  rill-marks  about 
shells,  and  ripple-marked  slabs,  but  in  mud-cracks  produced  by  sun-drying. 
In  all  these  respects  it  compares  with  the  Potsdam,  which  separates  the  Ta- 
conicfrom  the  Lower  Silurian." 

Certainly  a  sand  deposit  that  extended  from  May  Hill  in  England  to  Lake 
Huron  and  Tennessee  in  America,  must  exhibit  the  character  of  a  shore  de- 
posit in  some  places,  but  could  not  possibly  have  done  so  everywhere.  Cer- 
tainly in  its  many  hundreds  of  miles  of  outcrop  in  Pennsylvania  itshows  noth- 
ing of  that  character.  The  fine  grain  of  almost  all  of  the  sandstone  layers  of 
its  upper  and  lower  divisions  and  the  loamy  nature  of  its  whole  middle  di- 
vision, is  satisfactorily  good  evidence  that  the  great  Medina  sea  was  not 
shallow,  but  deep  ;  and  the  pebbles  of  its  conglomerate  beds  are  so  small 


708  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

To  this  I  object :  1.  the  almost  universal  conformability 
of  the  Oneida  upon  Hudson  river  formation  ;  2.  the  ab- 
sence of  pre-oneida  plications;  3.  the  impossibility  of  ob- 
taining the  principal  materials  of  the  Oneida  conglomerate, 
out  of  any  known  Hudson  river  strata  ;  4.  the  fact  that 
Oneida  deposits  still  remain  far  south  of  the  Hudson  river 
belts  (as  at  Greenwood  lake  in  New  Jersey) ;  5.  and  above 
all,  the  fact  that  at  the  Schuylkill  Water  Gap,  where  the 
Oneida  rests  at  right  angles  on  the  apparently  eroded  edges 
of  Hudson  river  slate,  there  is  in  reality  a  snapped  anticli- 
nal and  downthrow  of  the  slates,  and  no  unconformability. 

Mr.  Davis  shows  the  Lower  Helderberg  conformably  over- 
lying the  Hudson  rioer  "sandstones,"  in  a  synclinal. 

At  first  glance  this  would  seem  to  settle  the  question  of 
land  elevation  and  subsequent  subsidence ;  and  he  there- 
fore speaks  of  a  long  interval  of  time  (Oneida,  Medina  and 
Clinton  ages)  during  which  no  deposits  took  place. 

But  a  little  consideration  will  serve  to  show  the  uncer- 
tainty of  this  kind  of  evidence.  For,  during  all  these  ages 
it  no  doubt  rained  as  often  as  it  rains  now  ;  and  if  so,  all 
land  surfaces  must  have  suffered  erosion  ;  and  yet  the  Hud- 
son river  slates  in  his  Catskill  section  are  not  eroded  ;  they 
could  not  therefore  have  been  rained  on  i.  <?.,  they  could  not 
have  been  above  water. 

The  alternative  is  10  imagine  a  stoppage  of  deposit  with, 
out  elevation  of  sea  bottom.  This  is  not  impossible,  but  very 
improbable.  For,  the  Oneida  was  heavily  deposited  a  few 

that  they  could  be  carried  out  some  hundreds  of  miles  from  shore,  as  De- 
lesse  has  shown  the  pebbles  of  the  Loire  are  now  slowly  worked  along  out- 
ward over  the  sloping  bed  of  the  Bay'of  Biscay  into  the  deep  Atlantic. 

The  assertion  that  it  "  always  rests  unconformably  on  the  Hudson  river 
group  is  unwarranted;  because  not  the  thousandth  part  of  the  formation 
is  visible  at  the  surface;  and  because,  as  1  state  in  the  text,  an  examina- 
tion of  many  hundreds  of  miles  of  outcrop  contact  of  III  and  I  Vat  the  pres- 
ent surface  has  shown  not  non-conformability  but  conformability.  The 
"Water  Gaps  of  middle  Pennsylvania  furnish  abundant  evidence  of  the  fact. 

A  very  good  evidence  of  deep  sea  deposition  is  the  almost  total  absence  of 
oblique-bedding  in  IV,  showing  that  its  sands  and  muds  were  not  subject  to 
the  tidal  currents  of  shore  deposits  and  shallow  water.  In  this  respect  it  is 
in  marked  contrast  with  the  Pocono  formation  No.  X,  which  contains  the 
Tipton  Run  coal  beds  and  was  a  shallow  water  deposit,  as  will  appear  in  a 
future  chapter. 


CONFORMITY   OF   IV   UPON    III.  709 

miles  west  of  Newburg.  and  from  there  on  for  hundreds  of 
miles  westward  and  southwestward. 

An  easier  hypothesis  would  be  to  consider  the  "  Hudson 
river  sandstones"  which  lie  beneath  the  limestones,  to  be  a 
finer  part  of  the  same  deposit  as  the  Oneida  and  Medina 
conglomerates  and  sandstones  elsewhere. 

But  there  is  another  alternative,  in  view  of  the  close 
proximity  of  vertical  and  overturned  strata  between  the 
quarry  and  the  banks  of  the  Hudson.  The  crumpling  which 
Mr.  Davis  so  eloquently  describes  and  so  artistically  por- 
trays has  been  produced  by  the  sliding  down  upon  itself 
and  mashing  together  of  the  still  moist  formations  on  the 
western  slope  of  the  Hudson  river  uplift.  Precisely  simi- 
lar crumplings  characterize  the  same  limestones  all  along 
the  north  foot  of  the  Medina-Oneida  mountain  range 
through  New  York,  New  Jersey  and  Pennsylvania.  And 
it  is  in  front  of  these  crumplings  at  the  Schuylkill  water 
gap  that  the  great  fault  occurs  which  plunges  the  edges  of 
the  slates  underneath  the  bottom  of  the  conglomerate. 

It  should  be  kept  in  mind  that  our  massive  formations 
(XII,  X,  IV)  act  independently  of  the  softer  formations  be- 
tween them,  preserving  their  own  larger  plications  intact 
and  for  themselves,  and  compelling  subjacent  and  super- 
jacent  formations  of  inferior  tenacity  and  greater  ductility 
to  conform  to  limited  spaces  by  crumpling  and  sliding.  It 
is  quite  possible  that  the  faulted  edges  of  the  missing  rocks 
may  lie  deeply  buried.  At  all  events,  such  is  not  so  violent 
an  hypothesis  as  that  the  Hudson  river  slates  remained  two 
or  three  geological  ages  out  of  water  without  suffering  the 
least  erosion. 

Non-conformity  of  IV  upon  III  has  been  argued  from  the 
presence  of  pieces  of  shale  in  IV.  But  there  are  also  dis- 
tinct bands  of  intercalated  slate  between  the  sandstones. 
Even  supposing  fragments  of  foreign  slate,  they  could  not 
come  from  neighboring  Hudson  river  outcrops.  For,  if  the 
Oneida  was  deposited  over  the  whole  region  of  Northern 
New  Jersey  as  far  south  as  Greenwood  lake,  how  could  any 
shore  produced  by  an  upheaval  at  the  close  of  the  Hudson 
River  age  be  near  enough  to  furnish  such  materials  as 


710  GEOLOGICAL   SURVEY    OF   PENNSYLVANIA. 

those  of  which  the  Oneida  is  composed  ;  and  how  could 
"'pieces  of  Hudson  river  slate"  get  into  the  Oneida? 

But  the  most  complete  evidence  that  there  was  no  change 
in  the  relations'of  land  to  water  at  the  top  of  the  slate  for- 
mation No.  Ill,  and  before  the  deposit  of  the  great  sand- 
rocks  of  No.  IY,  comes  from  the  shape  of  the  Kittatinny 
mountain  along  its  whole  line  from  the  Delaware  water  gap, 
past  the  Lehigh  water  gap,  to  the  Berks  county  corner,  and 
far  beyond.  Any  erosion  of  the  slate  formation  previous 
to  the  deposit  of  the  Oneida  sandstone  beds  would  have 
made  the  outcrop  of  the  Oneida  beds  very  irregular.  It  is 
on  the  contrary  remarkably  regular ;  and  the  synclinal 
sandstone  crest  in  Offset  mountain,  just  east  of  the  Wind 
Gap,  lies  quietly  in  a  synclinal  of  slate  ;  all  the  rocks  dip- 
ping in  conformity.  Any  slight  difference  in  angle  re- 
corded in  the  Water  Gaps  between  the  sandstone  beds 
above  and  the  slate  beds  on  which  they  rest  must  be  due 
either  to  imperfect  instrumentation  ;  or  to  the  concealment 
of  the  actual  plane  of  contact ;  or  to  the  inevitable  slip  of 
the  upper  rigid  mass  on  the  lower  flexible  mass  in  the  pro- 
cess of  uplifting  the  whole  30°  or  40°  from  the  horizontal. 
When  this  uplifting  reached  90°  at  the  Schuylkill  water  gap, 
a  great  fracture  took  place,  and  the  whole  sandstone  mass 
shot  upright  into  the  air,  grinding  the  edges  of  the  slate 
mass,  which  remained  nearly  horizontal,  to  a  smooth  plane.* 

Along  the  whole  range  of  mountain  in  Northampton  and 
Lehigh  counties,  the  upper  limit  of  the  slates  rises  to  the 
top  of  the  long  slope,  to  within  about  200  feet  of  the  actual 
crest  of  the  mountain,  where  the  cliffs  of  Oneida  commence. 

*  At  the  Lehigh  Water  Gap,  on  the  east  bank  of  the  river,  near  the  railroad 
bridge  over  the  wagon  road,  massive  conglomerate  strata  at  the  base  of  IV, 
ascend  at  an  angle  of  30°  to  the  crest  of  the  mountain.  This  conglomerate 
consists  of  white  and  black  pebbles  an  inch  in  diameter.  Fine  grained 
sandstone  beds  ^overlie  and  underlie  the  conglomerate.  Fifty  feet  lower 
than  the  conglomerate  the  rocks  are  concealed  for  50  feet,  and  then  under- 
lying sandy  slates  appear  gradually,  passing  downward  into  the  top  slates 
of  ill,  which  soon  after  turn  over  an  anticlinal  and  dip  south.  It  looks  as 
if  the  concealed  interval  is  the  plane  of  a  fault,  and  the  north  dipping  slates 
a  downward  brush.  But  there  is  no  proof  of  non-conformability,  and  it  is 
quite  possible  that  the  anticlinal  arch  is  unbroken,  just  as  in  the  case  of  the 
anticlinal  behind  the  Hole  mountain  at  the  Swatara  Water  Gap. 


CONFORMITY   OF   IV    UPON   III.  711 

Downwards  the  mountain  slope  dies  away  in  the  slate  plain, 
chiseled  by  a  thousand  brooks  which  collect  the  rain  water 
and  continue  the  operation  of  lowering  gradually  the  gen- 
eral level  of  the  slate  belt. 


712  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 


CHAPTER  LIU. 

Tfte  mineral  worthies sness  of  the  North  Mountain  along 
the  Great  Valley  and  of  all  the  other  mountains  of  IV 
in  Middle  Pennsylvania. 

This  is  a  fixed  fact.  There  is  not  a  valuable  mineral  of 
any  kind  in  the  Oneida  or  Medina  formations. 

In  the  mountains  of  IV  there  is  nothing  but  worthless 
slate  and  common  coarse  and  fine  sandstones,  the  outcrops 
of  which  make  the  crest  and  back  slope  of  the  mountains, 
and  the  great  ribs  of  rock  in  the  gaps  where  the  rivers  break 
through.  Some  of  the  layers  yield  excellent  building  stone  ; 
but  building  stone  is  a  drug  in  the  market  in  Pennsyl- 
vania. Almost  every  citizen  of  the  state  can  build  a  stone 
house  or  barn  by  digging  a  hole  on  his  own  farm  ;  so  that 
what  is  valuable  to  himself  is  of  no  value  to  his  neighbors, 
much  less  to  commence.  The  limestone  of  the  valley  is  a 
better  building  material  than  the  sandstone  of  the  mount- 
ain, and  more  easily  tobtained  ;  therefore  the  sandstone 
rocks  may  be  said  to  be  worthless.  Occasionally  a  piece  is 
wanted  for  the  hearth  of  an  iron  furnace. 

There  is  no  gold,f  no  silver,:}:  no  copper,  no  lead,  no  tin 

fTLie  latest  deception  respecting  a  gold  mine  in  No.  IV  occurred  two 
years  ago  in  the  neighborhood  of  Jack's  Narrows  in  Huntingdon  county, 
where  a  company  was  formed  to  mine  gold  in  Jack's  Mountain  west  of 
the  Juniata  river  at  Mapleton.  What  gave  rise  to  it  I  do  not  know,  but  it  is 
probable  that  a  trace  of  gold  was  found  in  some  pebbles  in  the  conglomerate, 
such  as  is  described  in  the  geology  of  the  Schwangunk  Mountain  in  New 
Jersey.  All  quartz  seems  to  have  a  trace  of  gold  in  it.  But  gold-bearing 
quartz  veins  have  no  existence  in  the  mountains  of  No.  IV. 

}  Nothing  can  be  >more  ridiculous  than  the  report  of  silver  veins  in  any 
mountain  of  IV.  As  gold  goes  with  quartz  silver  goes  with  limestone.  If 
there  were  faults  filled  with  lead  ore  in  the  Medina  Mountains  more  or  less 
silver,  if  only  a  trace,  would  be  found  in  the  lead  ore.  But  no  lead  ore  vein  is 
known  in  Pennsylvania  in  any  of  its  mountains  of  IV.  The  lead  ore  is  con- 
fined to  the  limestone  valleys. 

The  remarkable  cross  fault  lead  veins  of  [the  Schwangunk  Mountain  of 
IV  east  of  the  Delaware  have  already  been  noticed.  None  such  have  been 


MINERAL    WORTHLESSNESS   OF   MOUNTAINS   OF   IV.      713 

in  these  mountains.  All  the  old  Indian  stories  about  lead 
ore,  and  all  the  lying  assurances  of  wandering  miners  that 
they  have  discovered  gold  and  silver  ores  in  the  mountain 
amount  to  nothing  at  all. 

As  for  iron  ore  the  only  show  of  it  is  in  the  slates  just 
under  the  sandstone  near  the  summit.  These  top  slates  con- 
tain enough  iron  to  coat  the  stones,  and  to  make  little  iron 
ore  bogs  lower  down  the  slope  where  the  springs  of  water 
issue.  The  iron-coated  sandstones  are  of  course  worthless. 
The  bog  ore  is  good  enough,  what  little  there  is  of  it,  and 
mixes  nicely  with  other  ores  ;  but  the  farm  clearings  where 
these  bogs  lie  can  hardly  be  said  to  be  a  dollar  more  valuable 
for  them.  There  is  no  iron  ore  bed  which  could  be  found 
by  searching  for  it.  The  iron  is  distributed  through  the 
slate  and  cannot  be  mined.* 

On  the  backside  of  the  mountains  of  IV  run  outcrops  of 
the  valuable  iron  ore  beds  of  the  Clinton  formation  No.  V, 

noticed  in  that  mountain  from  Port  Jervis  westward  in  New  Jersey,  nor  in 
any  mountain  of  IV  in  Pennsylvania.  When  I  was  surveying  the  Strouds- 
burg  country  in  1839,  I  learned  that  a  geological  tramp  from  Germany  had 
been  deluding  the  people  into  preposterous  mining  operations  in  the 
Pocono  Mountain.  There  were  traditions  of  sixteen  different  Indian  silver 
ore  veins  in  the  Kittatinny  Mountain  east  and  west  of  the  Wind  Gap.  This 
impostor  told  the  people  that  he  had  found  one  of  these  veins,  had  traced  it 
across  the  Aquanchicola  Creek  valley,  across  Godfrey's  ridge,  across  Broad- 
head's  creek  near  Stroudsburg,  across  the  Devonian  hills  to  the  foot  of  the 
Pocono  Mountain  escarpment  and  up  the  escarpment  to  a  place  where  it 
could  be  successfully  mined.  He  collected  one  or  two  thousand  dollars  in 
•small  sums  from  the  farmers  and  village  storekeepers,  and  kept  him- 
self and  one  or  two  hands  at  work  for  eighteen  months  making  a  large  hole 
in  the  face  of  the  mountain,  and  then  disappeared  leaving  the  hole  behind 
him.  Such  is  a  history  of  fraud  many  times  repeated  in  the  last  fifty  years. 

*  One  remarkable  exception  to  this  statement  must  be  noticed.  There  is 
a  gash  fault  across  Black  Log  Mountain  west  of  Orbisonia  in  Huntingdon 
county,  which  was  filled  with  limonite  iron  ore  long  before  the  mountain 
and  valley  surface  of  that  country  was  established  at  the  present  level. 
Nothing  of  that  sort  escapes  the  keen  eye  of  the  hunters  and  farmers  of  any 
region.  The  search  for  iron  ore  keeps  men  and  boys  on  the  qui  vive  ;  and 
this  curious  and  exceptional  deposit  was  exploited  by  furnace  men  and  ex- 
hausted. No  other  such  instance  is  known  in  our  state,  and  probably  no 
other  exists.  It  is  strictly  analogous  to  the  lead  veins  of  the  Schawngunk 
Mountain  east  of  Port  Jervis  ;  for  the  Black  Log  Mountain  is  shivered  by 
cross  faults  in  the  same  manner ;  as  exhibited  in  the  Rock  Hill  Gap  and  in 
the  gangways  of  the  fossil  ore  mine  southwest  of  Orbisonia. 


714  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 

block  ore  aud  fossil  ore.  These  beds  have  been  foun  dand 
opened  here  and  there  along  the  North  Mountain,  but  with- 
out financial  success.  In  1839  I  discovered  the  block  ore 
just  behind  the  mountain  on  the  bank  of  the  Little  Schuyl- 
kiJl  opposite  Port  Clinton.  Since  then  the  bed  has  been 
opened  ;  but  the  attempt  to  mine  it  was  abandoned  ;  the  ore 
was  poor  and  the  bed  thin.  And  this  appears  to  be  the 
case  along  the  whole  line  for  a  hundred  miles.  Back  of 
Cowan's  Gap  in  Fulton  county  it  was  tried.  In  the  Lit- 
tle Cove  southwest  of  Mercersburg  it  is  of  little  value. 
But  this  has  nothing  to  do  with  the  Oneida  and  Medina. 

If  any  religious  mind  asks  why  God  made  the  mountains 
of  IV  without  a  single  valuable  mineral  in  it — a  question 
which  has  been  more  than  once  put  to  me  respecting  other 
mountains  mineralogically  worthless — the  answer  is  a  plain 
one  and  should  be  satisfactory  to  any  reasonable  man. 
Mineral  value  is  not  the  only  kind  of  value.  The  true  worth 
of  mountain  land  is  to  cool  the  air  and  condense  its  mois- 
ture into  rain,  to  feed  the  streams  which  supply  the  valleys, 
and  to  preserve  the  forests.  For  such  benefits  as  these  the 
inhabitants  of  the  Great  Valley  should  be  ever  thankful  to 
the  North  Mountain — without  looking  so  fine  a  gift  horse 
in  the  mouth — or  pining  for  gold  or  silver  mines,  which 
after  all  are  not  half  so  desirable  as  fertility  and  water 
power. 


FOSSILS   OF   ONEIDA   AND   MEDINA   NO.  IV.  715 


CHAPTER  LIV. 
Fossils  of  Oneida  and  Medina  No.  IV. 

The  whole  formation  is  remarkably  destitute  of  remains 
of  animal  and  vegetable  life.  The  abundance  of  molluscan 
and  crustacean  forms  in  the  preceding  Trenton  and  Hudson 
River  ages  seem  to  have  given  place  to  a  barrenness  of  all 
living  existence.  Nothing  but  the  stony  casts  of  macerated 
seaweeds  are  to  be  found  in  the  two  or  three  thousand  feet 
of  rock  strata  of  Oneida  and  Medina  age  in  Pennsylvania. 
These  are  so  abundant  in  some  places  as  to  cover  extensive 
surfaces  of  the  sandstone  beds.  Their  forms  are  repre- 
sented on  plate  CXI,  page  716.  They  are  most  abundant 
in  the  upper  division.*  This  species  of  seaweed  is  called 
Arthrophycus  Tiarlani.  The  surfaces  of  great  slabs  torn 
from  the  Tussey  Mountain  outcrops  on  the  Juniata  and 
floated  by  ice  down  the  bed  of  the  river,  are  completely 
covered  with  a  network  of  its  stony  casts  in  high  relief. 

In  New  York  State  James  Hall  describes  from  the  mid- 
dle division  of  IV  two  small  lamellibranch  shells  Cypricar- 
dia  orthonota,  and  Modiomorpha  alata  (Conrad's  Unio 
primigenius),  and  two  small  gasteropod  shells,  BelleropJion 
trilobatus  (Conrad's  Planorbis  trilobatus)  and  EnompTia- 
lus  (Cyclostoma,  Pleurotomaria}  pervetustus.  the  earliest 
known  appearance  of  this  kind  of  shell.  Dana  says  that 
one  of  the  most  common  Medina  brachiopod  shells  is  the 

*Prof.  W.  B.  Rogers,  Geo.  Va.,  1884,  p.  175,  says  that  "near  the  upper  limits 
of  the  group,  as  well  as  in  the  shaly  bands  beneath,  organic  impressions  are 
often  abundantly  discovered.  The  thin  slabs  of  buff  and  olive  sandstone 
lying  near  the  top  are  particularly  rich  in  these  remains,  among  which  may 
be  noted  as  abundant  a  small  globose  terebratula,  and  at  least  two  well 
characterized  species  offucoides  [sea  weeds].  Cylindrical  markings,  simi- 
lar to  those  of  No.  I,  are  often  exhibited  in  great  numbers  in  the  more  com- 
pact and  fine-grained  white  or  pinkish  white  strata. 


716  GEOLOGICAL   SURVEY   OF   PENNSYLVANIA. 


HarUnla  halll.  (Go.pp.rt.  Fo«.  Klor.  de.  Ueberg,  1. 

~ 


Conrmd.   (tic.  Trfn/bn  in  Pa. 


Collect*?  from  /to,  at  Pert  C2w  ton; 
and  front  IVi.c,         ' 


Omitted  from 
"&*nf»*fou 

*       /U/a/At  above 
„     <o    f« 


Cypricardla orthonota.  Ha/I. 


Modiomorphaal«aU.«atf. 
(G/on'(a.tci 
alata, 
(llnio  prhmyfiui 


Bellerophon  trilobatua  M*n*lfa  MflaJ 


FOSSILS   OF   ONEIDA   AND   MEDINA   NO.  IV.  717 

wedge-shaped  Lingulella  cuneata.*  He  figures  also  two 
lamellibranch  shells  Modiolopsis  orthonota,  and  Modiolop- 
sis  primige/iia,  and  the  two  gasterpods  Pleurolomaria 
litorea,  and  Bucanella  trilobala  (Conrad's  PlanorMs  above 
mentioned).  He  adds  that  a  considerable  number  of  Me- 
dina species  lived  on  into  Clinton  times.  In  fact  the  dearth 
of  Medina  life  in  Pennsylvania  was  due  to  peculiar  circum- 
stances, as  the  astonishing  thickness  of  the  sand  deposits 
sufficiently  attest.  In  other  parts  of  the  earth's  waters 
there  was  an  abundance  of  life.  For  example,  the  rocks  of 
this  age  exposed  on  the  island  of  Anticosti  in  the  Gulf  of 
St.  Lawrence  are  crowded  with  fossil  forms. f 

The  English  May  Hill  sandstone  formation,  the  repre- 
sentative of  our  American  Oneida-Medina  formation,  was 
deposited  in  waters  so  full  of  life  that  261  species  (of  91 
genera)  have  been  found  in  it,  136  species  being  peculiar  to 
it.  Among  them  is  the  oldest  known  sea  urchin,  Palceec/ii- 
nus  phillipsi,  Forbes4 

The  oldest  insect  recorded  up  to  1887,  Palceollattina 
douvillei,  was  found  on  a  slab  of  May  Hill  Sandstone  at 
Turques  in  Calvados,  France,  by  C.  Brongniart  It  is  one 
wing  of  a  cockroach,  distinguished  from  all  other  known 
cockroach  wings,  fossil  or  recent,  by  the  length  of  its  anal 
vein,  and  the  narrowness  of  the  axillary  area.§ 

The  abundance  of  plants  and  animals  of  the  sea,  and  the 
existence  of  land  beetles  being  demonstrated,  it  follows  as 
a  matter  of  course  that  the  land  surfaces  sustained  a  vege- 
tation of  their  own.  No  remains  of  land  plants  have  been 
found  of  the  definite  Medina  age  ;  but  a  superb  fossil  fern, 
Eopteris  morierei,  Saporta,  has  recently  been  discovered  in 

*  The  figure  on  Plate  CXI,  from  Hall's  Pal.  X.  Y.  Vol.  IV,  shows  three  of 
these  little  lingulas  (lingulellas)  stranded  on  a  beach  over  which  the  waves 
dragged  the  fine  sand  into  pointed  ridges  in  the  wake  of  the  shells.  Ripple 
marks  and  mud  cracks  prove  that  the  beds  were  out  of  water  and  exposed 
to  the  sunshine,  and  that  the  sunshine  was  as  genial  then  as  it  is  now. 

t  Dana's  Manual  of  Geology,  3d  Ed.,  1880,  p.  223. 

+  Figured  by  him  in  the  early  Memoirs  of  the  Geol.  Sur.  G.  Brit.,  Vol.  II, 
plate  XXIX,  p.  674.  Desor's  Synopsis  des  Echinides  fossiles,  1856,  page  159. 
Geikie's  Text  Book,  1882,  page  674. 

§  Woodward's  paper  in  Geol.  Mag.,  Feb.,  1887,  p.  49,  quoting  ComptesRen- 
dus  A  cad.  d.  Sci.  Paris,  No.  29,  Dec.  26,  1884. 


718  GEOLOGICAL   SURVEY   OF    PENNSYLVANIA. 

the  schists  of  Anglers.  These  schists  are  placed  by  French 
geologists  at  or  near  the  base  of  the  Middle  Silurian,  which, 
in  America,  may  be  assigned  to  either  the  upper  part  of  No. 
Ill,  or  the  Oneida,  No.  IVa.  It  is  a  pinna  (leaf)  with  large 
leaflets  and  a  perfectly  distinct  venation  resembling  a  Neu- 
opteris  of  the  Coal  Measures.  Of  this  fern,  our  lamented 
palseobotanist  Leo  Lesquereux  remarked  that  "it  plainly 
proves  that  the  land  vegetation  of  that  age,  including 
already  plants  of  so  advanced  types,  must  have  been  varied 
in  character.  Therefore,  according  to  the  law  of  evolution, 
it  is  evidence  that  a  still  more  ancient  land  flora  existed, 
probably  contemporaneous  with  the  first  appearance  of  the 
vegetable  marine  flora." 

Several  years  ago  Lesquereux  discovered  land  plants  in 
the  Lower  Silurian  rocks  near  Cincinnati,  and  descanted  on 
their  importance.  His  determinations  were  at  first  doubted, 
but  have  since  been  accepted  by  Saporta  and  other  authori- 
ties. The  confirmation  of  Lesquereux' s  views  afforded  by 
the  French  fern  is  all  the  more  valuable  inasmuch  as  this 
fern,  which  lived  in  an  early  Palaeozoic  age,  resembles  those 
which  grew  in  the  much  later  Carboniferous  times  ;  and  the 
earth's  surface  was  no  doubt  clad  locally  with  ferns  of  that 
type  during  all  the  ages  intervening  ;  so  that  Upper  Silu- 
rian, Devonian  and  Subcarboniferous  Neuropterids  may 
turn  up  in  the  future  exploration  of  deposits  favorably  situ- 
ated in  regard  to  ancient  shore  lines,  from  which  soil-laden 
rivers  debouched.  Such  ferns  are  therefore  no  longer  to  be 
accounted  characteristic  of  the  Coal  era  ;  and  what  is  true 
of  ferns  must  be  true  of  all  other  kinds  of  fossil  forms.  It 
is  the  general  fades  or  aspect  of  its  flora  or  fauna  which 
characterizes  an  age,  and  not  any  one  species.  The  identi- 
fication of  the  same  deposit  in  two  geological  regions,  far 
removed  from  each  other,  by  means  of  one  or  two  "charac- 
teristic forms"  must  always  be  done  at  the  risk  of  making 
some  great  mistake  certain  to  be  discovered  in  the  further 
progress  of  the  science. 

It  should  always  be  kept  in  view  that  fossil  plants  were 
drifted  seaward  from  the  mouths  of  rivers  draining  certain 
kinds  of  land  ;  delivering  therefore  certain  kinds  of  mineral 


FOSSILS   OF   ONEIDA    AND   MEDINA   NO.  IV.  719 

matter.  The  lithology  of  the  rock  must  be  quite  as  "char- 
acteristic" of  that  special  age  as  its  palseobotany.  As 
land  surfaces  become  worn  away  their  river  detritus  changes 
character.  The  same  river  must  make  quite  different  de- 
posits in  successive  ages.  Moreover  the  drainage  system 
changes ;  rivers  run  in  other  directions  and  in  other  vol- 
umes ;  so  that  the  same  central  forest-covered  land  district 
may  furnish  very  different  successive  deposits  with  the 
same  kinds  of  plants.  On  the  other  hand  changes  of  vege- 
tation are  often  rapid  ;  the  Delaware  and  Susquehanna 
rivers  are  floating  deciduous  leaves  and  twigs  now  into  the 
Atlantic,  whither  only  a  century  ago  they  floated  coniferous 
foliage  and  fruit. 

The  same  is  true  of  animal  fossil  forms.  The  stability, 
the  number,  size  and  association  of  types  has  always  de- 
pended upon  the  lithological  output  of  the  land-drainage. 
This  has  always  been  changing  in  its  direction,  intensity, 
extent,  and  mineral  constitution — the  changes  being 
brought  about  slowly  or  swiftly,  and  often  alternately,  not 
merely  by  movements  of  various  kinds,  but  by  secular  ero- 
sion, uncovering  deep  rocks  to  the  surface,  and  removing 
upper  rocks  from  it.  Therefore,  it  is  impossible  to  believe 
in  "characteristic  forms,"  in  the  dogmatic  way  in  which 
they  have  been  adopted  and  applied  to  stratigraphy. 

At  the  same  time  all  the  considerations  mentioned  above, 
while  throwing  doubt  on   "single  characteristic  forms,' 
tend  to  increase  our  faith  in  "characteristic  groups,"  and 
in  their  close  generic  relationship  to  characteristic  lithology. 


END    OF    VOL. 


QE 

15"7 

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